Webinar on 'The Shrewsbury Flaxmill Maltings Project'

The Shrewsbury Flaxmill Maltings Project 

Speakers: Nick Hill and Kate Gunthorpe 

Kate [00:01] ...in particular, I designed the skills training programme. Before working for Historic England, English Heritage, I was at National Trust. I've been working on major projects and grant schemes, and I'm currently working on the Covid Recovery Grant, the Heritage Stimulus Fund. I'm a chartered building surveyor and quantity surveyor, with conservation accreditation. 

Next to introduce himself is our main speaker, Nick Hill. 

Nick [00:31] Hello, everyone. I'm Nick Hill, National Conservation Projects Manager for Historic England. I recognise a few names amongst the gathered throngs. Sorry we can't be with you in person, but nice to see so many of you. I'm project manager for our main flagship project at the moment at Historic England, Flaxmill Maltings in Shrewsbury. I've been involved since 2014. I'm also a chartered building surveyor, like Kate, and accredited in conservation. Been with Historic England and English Heritage for 27 years now and also involved with some other major projects, like our big rescue project at Althorp Hall in Northamptonshire. So we'll get underway with the talk shortly. Back over to Kate. 

Kate [01:24] Thanks, Nick. For those of you that are new to Technical Tuesday, I'd just like to let you know a bit more about the Historic England Technical Conservation teams. We are a group of technical specialists, including conservators, scientists, engineers, surveyors. We undertake research and provide advice and guidance on technical conservation issues. The first link that Alice is posting in the chatroom takes you to the main technical advice page on our website. All our research reports and PDF guidance is free to download. The second link that Alice has got takes you to the catalogue that you can see here. 

Also, we have the Technical Conservation newsletter. This comes out via email on the first Tuesday of each month, and it'll update you on new guidance, publications and any forthcoming training events and webinars. If you'd like to add your name and you haven't already signed up at a previous webinar, just click 'Yes'. Clearly, most people are interested in that. That's great. And to be clear, this is for the technical conservation guidance and events only, not the general wider Historic England content. That's great. I think everybody's had a chance to do that. 

So, to hand over to Nick now, and we'll start off with our introduction. Thanks. 

Nick [03:01] I'll take over then, Kate. Thank you. So this is the start of the main presentation. Shrewsbury Flaxmill Maltings, its principal claim to fame as a historic building and the reason really why Historic England is involved is that it's the first iron-frame building in the world – a rather remarkable survival – and we'll looking at that in a bit more detail. 

The Flaxmill Maltings project has quite a number of different strands to it, but the principal one at the moment on site is the main mill and kiln project, which I'll be talking about and focusing on today, the big construction project. That on the screen as you see there is the main mill, all shrouded in scaffolding as it was for many years. That came down a year or so ago now, as the work is progressing. We're now in the fifth year of the major phase project on the main mill itself. 

So I'm going to start with just a bit of an introduction to the site, the key buildings and its history, because that's obviously the starting point for understanding what it's all about. In terms of the project, here we're looking at an aerial view from a couple of years ago now with the main mill stretching out the long building over on the left, the Jubilee Tower poking up above, that was added as a hoist tower; the kiln, big pyramid shape; and then there's a whole complex of other buildings – the warehouse with that corrugated iron tower poking up. And over on the right, the right foreground, the apprentice house – a whole series of buildings that were assembled through the course of the 19th century. 

So looking at the development of the site over its history, it started life as a flax mill. It was built as a flax mill as the first iron-frame building in the world in 1797, and it had 90 years as a flax mill near [indistinct], with the main mill you can see there in the centre, the long building, the first building on the site, rapidly followed by buildings like the cross mill, the warehouse and the apprentice house to combinate all sorts of other uses, including the labour force, and the dyehouse added in the 1850s. It was processing flax, taking from the raw product, drawing out the fibres through processes of heckling, and the spinning it into linen thread. It was principally often known as the spinning mill, the flax mill, because its primary product was that thread rather than woven linen cloth at all. 

So we'll go onto the next slide. This is really just picking out three key figures in the founding of the flax mill and getting underway of this major business enterprise. Top right there is-- top left, sorry, is John Marshall, who was the flax mill owner. He had a major business producing flax and linen up in Leeds, and this was an off-shoot down in Shrewsbury, encouraged here by some Shrewsbury connections, and the Benyon brothers who helped to finance it in the early years. So he was the driving force, and it continued in Marshall ownership right through for its 90 years life.  

To the right is William Hazeldine. He was the great ironmaster in Shrewsbury and was responsible for creating the iron frame itself, pouring all the cast iron at his foundry in Shrewsbury. He is the reason we have a bus in [indistinct]. He rose to be a mayor and played a key part really in this iron-frame building. He worked with Telford and others subsequently in his career and was quite a genius really. Telford later referred to him, this sort of magical property of being able to, in his early years of cast iron, to create structures and intricate shapes out of it. He called him Merlin Hazeldine, with his sort of magical art of transforming iron. 

But the key figure, really, is the one at the bottom. Sadly, we don't have an image of him, Charles Bage, who was the designer. What we do have from him is a whole series of letters that he wrote to someone else who was following this whole development of iron frames and pressing the bounds of what could be done, and this is just a short excerpt of a letter we have from Charles Bage to William Strutt. Charles Bage had an early interest in iron frames. His iron structures-- His father owned an iron mill, but he was also a land surveyor, a wine merchant, a man of many parts, really, and he has this series of letters where this was really the leading edge of what they were really trying to do at the time – inventing new ways of structure, new ways of building, as part of a sort of wider-- often called the Shropshire or the Midlands enlightenment figures like Wedgwood, Telford, Robert and Charles Darwin, Abraham Derby, of course, who was the great founder of Iron Bridge, the works there and the specialist skills. 

So here you can just see, if you can read it there-- This is just a little clip from one of his many letters, where he says, 'We are differently advised about the strength of pillars. This shape...', and he draws out the little cross, cruciform shape, which is the one they used for the columns in the main mill. 'Nearly resembles yours and is doubtless the strongest'. As we now know, it wasn't the strongest way to use the material. We now know it's a circular hollow section is the better use of material, but that was what they thought, and they were at the leading edge of those experiments. 

So it's all about-- this is an earlier internal view of the iron frame. It's all about that interior of the building rather than the exterior and what happened with the structure inside of it, which I'll come on and say a few more words about. The reason, though, the reason for the flaming building in the bottom right there is that the whole point of this was not just to come up with a new structural technique. It was actually all about making a fire-proof building. There'd been a whole series of major burn-outs of mill buildings, total loss, all the contents, machinery and so on – a very great expense. And the race was on to find a building that could built fire-proof, with iron frames, iron beams as well – that's the innovation; the flax mill was iron beams – and as you see here, brick arched floors, so we're eliminating timber and hence moving forward in that way. 

There's been a huge amount of research, which Historic England and others have done over the last several decades after the flax mill, previously known as Ditherington Mill in the book that was published by Historic England a few years ago that you see here. It was rediscovered in the post-war era actually by some Americans who were researching the early history of the skyscraper and came to realise that this actually still existed, surprisingly enough – one of the very rare survivals as well as being the first. 

So here you see the great intricacy of the iron frame. It's a five-storey building with columns, beams, a whole intricate array of joints that you can see here – also, some of the earliest use of nuts and bolts in any sort of structural way at all. And the other remarkable thing that's just worth pointing out with the right-hand drawing here is the fact that within the iron frame there on the ground and the third floors, if you look at the left-hand as well, they had this sort of U-shaped column, which was actually purpose made to take the line shaft for the mill machinery. So not only was this the first iron-frame building in the world, but it was also intricately designed to take all of the intended machinery of the flax-spinning process. 

The flax industry then went into some decline towards the end of the 19th century. The Marshalls closed it down eventually in the 1880s. It lay empty for a few years and then took on a new lease of life, rather remarkably, repurposed as a maltings. William Jones Maltsters took it over, and it's that really that it owes its survival to. So many early industrial buildings, once they've served their purpose get flattened and rebuilt as something else and redeveloped, but here in a rather remarkable case of early conservation – though I'm sure they didn't think of it as conservation at the time; it was just economical reuse – the building was repurposed as a maltings. 

And it had another 90 years as a maltings, and it's that that it's known, particularly in Shrewsbury, still as a maltings. It was what then became, over the years, a very old-fashioned sort of maltings, with a floor maltings with the barley laid out to germinate on the great floors for which it was very suitable. And the kiln, which is also part of the current project, the big pyramid roof-shaped building, was added at this time, along with some other later structures, and that was, at the time, said to be the largest single kiln in Europe – remarkable structure, which we'll see a bit more of as we go through. 

Here's the maltings then, with this great-- The barley germinated in tanks at one end, spread out across the floor and then taken off into the kiln for roasting and making into malt for beer. One of the key things just to point out on the old black and white photograph from around 1900 there is that in order to become a maltings, the major change to building was that they blocked up two out of every three windows, and the remaining windows, they are made smaller and as shuttered openings, because they wanted a dark, humid closely controlled environment for the malt, but obviously that was a major change to the building, which we then had to face a changing again, as we'll come onto as we go through. 

So, that's really just a very quick overview for the history. For anyone who's interested in more, there's an awful lot more information available on the website, the Friends of the Flax Mill Maltings website, and also in the Historic England book. It has been very thoroughly researched. 

So, just to give a little bit of the history of how we became involved. The maltings closed in 1987 and then there was this huge complex that you see there of buildings in increasingly poor and derelict condition. There was a succession of three attempts by different developers to save it and rebuild it, refurbish it for new uses, each one of those, unfortunately, came apart. It was just too big and too complex, really. The structural challenges in particular were too big for them. 

So eventually in 2005 as part of our very exceptional last resort as we stepped in with Shropshire Council also as well, as one of the key partners, to take the whole site over, six and a half acres of the industrial buildings, the surrounding brownfield land, and it's taken a long time, as you can see, for it to get underway as a project. Kate, I'll bring you again in there, I think, and we'll move forward into the next section. 

Kate 15:41 Thanks, Nick. Really useful to start us off there. Shrewsbury Flaxmill Maltings, obviously a great example of our industrial heritage. It's got local, national, international significance, and we call it the grandparent of the modern skyscraper. But as you say, very clearly at risk, hence Historic England getting involved, but this also reflects a wider interest in industrial heritage for Historic England. It goes back to a survey in 2011 that found that the numbers of industrial buildings at risk was three times great than the national average for listed buildings at risk. 

So Historic England now has a lot of guidance and case studies on this area, and I can see that Alice has popped the link in there that you can follow. But with this, it's really key to find viable and sustainable uses. As our architects FCB say, 'Putting the building back to work', and I know, Nick, you've been involved in a number of past projects, so we thought in this webinar, it'd be really interesting to compare some different approaches, so that's the next area that we're going to look at now. 

Nick 17:04 Thanks very much, Kate. Yeah, just a word to Alice. The pointer at the moment, which I might want to use from time to time, seems to have got disabled at the moment, Alice. I don't know whether you are able to make it work, but anyway, I'll carry on to the next slide. Oh yeah, that's good. Thanks. Yeah. 

So, yes, I just wanted to in a way, sort of, set the context of the overall situation and approach with the Flaxmill Maltings. In terms of reuse of industrial buildings, this is a project which I and some of the Shrewsbury Flaxmill Maltings consultant team have worked on in recent years, Middleport Pottery in Stoke-on-Trent, which I suppose is the ideal industrial reused project because actually, it was built as a wonderful model pottery in Stoke-on-Trent in the 1880s, and it continues as that. It now has to absorb some other uses as well, and visitors and so on and so forth, but actually, this was a remarkable project because a lot of it was really about repairing the buildings and keeping the industry of pottery making going. That, of course, is a very, very rare thing. Particularly, as time changes, methods change and so on, and there's been some method changes here, but it's an ideal thing that can rarely happen.  

At the other end of the scale, perhaps, is this building, which was a particular project of mine that I worked on a few years ago in Birmingham – the J. W. Evans Silver Factory – and this used to be making silverware, very active factory up to the point where we took it over, but sadly, there was no future for it as a sort of economic business – too complex. So that's become a heritage museum and visitor site. We took it forward as sort of the most extreme case of conservers found where we kept everything exactly as it was. 

So those are, in a way, two ends of the spectrum for how industrial buildings can be taken forward into new futures. The Flaxmill Maltings is a perhaps much more normal sort of thing in that it really has to find a new beneficial use, be taken forward into a third age. It had a first age as a flax mill, second age as a maltings and, as our architects Fielden Clegg Bradley Studios like to say, the third age. Really looking forward to a whole new viable future. 

This is just an introductory slide looking at the variety of uses, which we'll come onto. So there's our main mill, five-storey main mail on the ground floor. We have the visitor use, open to the public. But above that, there are four flaws of commercial use for offices and then associated things: circulation, space and the service spaces at either end. You also see here future phases of the larger project, as yet unfunded, that we'll be taking forward on other buildings. So, that's just a quick overview in terms of the overall approach. 

What I wanted to do now was to pick out just a few particular aspects, really, of the project. So looking then at the main mill and kiln project and just to introduce that in the round. The key project, we're working quite closely with other partners, in particular, the Friends of the Flax Mill Maltings, who are a wonderful group of, principally, volunteers, just a few paid staff now, who have been managing the site during its sort of fallow years as far as they can – visitor attraction and doing tours and guided tours and events and so on, through some of the building works at the earlier phases, especially before Covid-19 obviously struck. And also, Shropshire Council have been key partners as I said, particularly the early years with the site purchase, and still very supportive because it really does form quite a large chunk of the urban infrastructure of Shrewsbury and has a key part to play in things like the big town plan, which is the larger planning initiative for the town. 

This major part of the project then. That's the budget you see there, just over £28 million. Hugely grateful to our principal funders, the National Lottery Heritage Fund. We now have one of the largest ever Lottery Heritage grants in the country at just under £21 million, which is taking us forward. It took, obviously, quite a long time to put all this project together and the funding and so on. And then there's the three phases. We're currently in phase three now and heading towards, we hope, completion of the major construction works in November 2021. 

Just to introduce the key project team, Historic England obviously. We have overall management of the project, but the detailed work is being taken forward for us by a whole team of consultants led by our architects Feilden Clegg Bradley Studios, structural engineers AKT II, our quantity surveyors Gleeds, our M&E consultants E3CE, landscapes LT Studios, and the main contractor who actually has won all three phases of the work is Croft Building and Conservation, who've been doing a great job on resolving all of the practical problems on site. 

So that's one of FCB's cutaways of the building, and just really to contrast, once again, the fact that the ground floor then is going to be the one open to the public, a visitor centre, café and so on, the upper four floors for commercial office use, and we're looking really to take this whole building forward into-- It is a major, dramatic changes, as you'll see, for a grade I-listed building. There are some huge changes needed. Each of those has had to be thought through very carefully in terms of how it impacts on the significance and history of the building. But it is a big vision to take this project forward – building forward – into a third-age centre of work, education, enjoyment and, above all, innovation really, which is where the building started as the first iron-frame building in the world. We want it to become a vibrant place once again. 

So I just wanted to pick out a few of the major design decisions and issues that we've had to face up to. There's obviously a myriad of issues that we've had to deal with, but some of the larger and more important ones and maybe things that sort of translate across to other projects and other buildings. This is the one I wanted to focus on first. There's three sort of design issues on the architectural side that I wanted to pick out, really, the first one being about compartmentation and subdivision of the spaces. We've been concerned about this, really, from the beginning in that the key significance of this building, its most important thing, really, is not how it looks from the outside, but this internal side, the iron frame and these great long vistas down. This is on the third floor, and we very much want to keep this as far as we can. The third floor is the best of these floors. It's the highest ceiling height. It has these U-shaped columns, which you can see just here with the cut-out for the line shaft that would have gone down, so that's what we want to keep. 

So on this particular floor, we've signalled this out as one of the most important, and we want to keep that as open plan as possible, as you see there, a single user using that as an open-plan space. But we have recognised very much that with four whole floors, we can't have them all, sort of, big open-plan offices unless we got really lucky to attract a single user, which we've not managed to identify yet, so we're recognising that we are going to have to have some subdivision. 

And for the area of subdivision, we've picked out then the first floor, which has less significance in that it's a lower ceiling height, doesn't have the columns. It's also having to be compromised by some of the structural strengthening works, which we'll come onto as well. So this is one where we've looked at introducing a corridor and some subdivision but trying as you can see here very much to keep, rather than a tight little corridor and dark little egg crate spaces, trying to keep a sense of openness, a generous, wide corridor, glazed partitions so that you do still get a sense of the great space that this was. 

The ground floor is interesting again in that here it is use for the public-access visitor centre managed by the Friends of the Flax Mill Maltings in future, with the cafe as well we want on this ground floor to be used both by visitors and by the surrounding community and not least all of the office workers. We've got space for 300 people in the floors up above, so we want to make this a vibrant centre. 

Initially, we had early discussions on this and were quite keen in the early years to retain this also as a big open-plan floor, but as we sort of went into the different-week requirements, we became aware that, really, we needed to separate the cafe from the rest of the space. And fortunately, history and understanding came to our aid in that here's the ground floor plan. We have a wonderful 1855 plan of the mill, which has all been dug out of the archives. This is in Shropshire Archives, these originals kept. And what you can see here is these cross walls. There are actually three of them on the original plan, which were there right from the beginning and the sort of building archaeological analysis also shows that these were part of the original 1797 structure. 

So actually, that gave us a rationale for introducing, once again, one of those partitions. They'd only been removed as part of the maltings phase in 1897, and meaning that we're able to-- but that sort of flows out of a relatively straightforward, in this case, but fundamental view coming out of the historical understanding of the building, its significance and where to put those key dividers. 

So the second aspect of the design that I wanted to talk about then is vertical circulation, because where to put the lift is often a big problem in a historic building, and sometimes, in industrial buildings, it's a problem. Other times, you have an ideal space. And here we have the kiln, and this was built, as I said, in 1897. This is a grade II structure and had actually been-- it had gone through some major changes also in the 1960s. So we recognise this was really about the only place that we could fit in the big lifts that we were going to need in order to bring the building into viable use into the 21st century. 

So here you really see the sort of boldness of the architect's vision for a third age coming to the fore. We've been taking forward this thing, so you can see where the original-- we've kept the original columns of where there was a floor. That floor had rusted out as one of the columns-- Just trying to get this pointer to work. One of the columns here rising up, but the floor there, it actually rusted out entirely and was a 1960s steel floor, so we decided, while keeping other key parts of the history of it, we've opened it up into this amazing atrium space. It is quite a stunning space with the lift shaft rising up through the middle of it, and that cracks at a stroke our major circulation problems. 

This is it taking shape now. You can see it is going to be an extraordinary space. We're presenting it very much as a raw industrial space with the steelwork exposed and lift shaft going up, and ramps across the upper part of the building with all the exposed brickwork is very much as finished. But while doing that, we have also been able to look after the archaeology that you see here, so that's all been carefully recorded, and so on. 

And very nicely also over here, this is on the right, one of the major furnaces. This is one of the principal parts of the machinery that still remains. That, although it looks maybe antique now, was only introduced in the 1960s, we've now come to understand, but it was the throbbing heart of the whole maltings operation, fuelling that with anthracite and roasting all the grain on the floors above. So we're able to keep key parts of this, and these are being kept very much in their sort of conservers-found state, rather like the Evans Project in Birmingham, which I talked about earlier as a raw industrial artifact that the visitors will be able to appreciate, and a key part of the history. 

So the next thing I-- third of the design aspects that I wanted to talk about then was the major change to the external elevations. Here, as I mentioned earlier, in the-- you can see the before and after here, design proposals from our architects, and you can see that in order to really bring this building back into use for anything other than black-box kind of uses, we were going to need to reintroduce windows. We had a clear understanding of where those windows had been, and one of the key things that we decided to do here was-- We could, of course, have restored all the windows, removed-- sorry. We could have removed all of the maltings windows and gone back to the whole of the flax mill pattern of windows, as you see here. So that's one of the new windows in the original flax mill large window openings that we've put back. 

Here on the right, you can see that brickwork opening, and we've retained the maltings windows. We felt very much that the maltings were part of the history of the site. We didn't really want to erase that, so we've kept both parts as being a significant contribution. It gives the building an interesting kind of 212 sort of rhythm, and maybe more interesting than just a great big array of windows. But we wanted-- Key thing really there is that we're not looking to restore everything back to 1797, which, as you all know, is a slippery slope to embark upon, but looking at keeping the best work of all periods. So that's what we've done with the windows here. Inside it's made this dramatic change from a brick box, very dark and filled as it was with scaffolding holding it all up, to a wonderful, light space inside with our fit-out works proceeding. 

So I think those are the three sort of key design challenges I wanted to look at. There's a view of it just a month or so ago with the scaffold down and working on the kiln there with the scaffold, but you get the overall view. And we've repainted the new name for the building in the place where the previous sign was, now with it sort of interrupted, but we feel happily enough, by the cut-outs of the new windows. 

So I wanted now to move on to some of the structural challenges. This has really been, particularly in the earlier part of the project, the most sort of complex, most difficult challenge that we've had, and certainly in my 35 years or so of working on historic buildings by far the most complex structural challenge I've ever faced with a building, both in terms of the design and the concept, which in particular in this case, the methodology and the contractors' way of actually making it buildable – our alternative approach. 

So, just first off, look at the problems of the building. It looks quite solid when you walk into it and look at it, but when you look at it sort of stretched out and in design, as it were, it's actually quite a spindly sort of cast-iron frame and, in particular, has the problem of cast iron, which is why, as the development of tall buildings and skyscrapers went on, cast iron receded into the past, really, because cast iron is great in compression, but very poor in tension. And when it does fail, as you can see here with this hairline crack on that beam there, that's a regular pattern of cracking on all of the side columns throughout the building. And that's because cast iron is subject to this cracking and brittle failure, and in particular, what's of great concern about it as a material that's unlike timber or steel, when it does give way, it gives way suddenly and without warning as a sort of sudden crack fracture, brittle failure rather than ending and giving before it fails. 

So what that means is that you then have to design nowadays for a very high factor of safety on cast-iron buildings – factor of safety of 5 is needed. And what we found here was that the factor of safety on some of the worst elements here we were getting was only about 2. 

So where do we go with that? Well, again, one of the sort of wider lessons and very applicable to many building uses in structural engineering terms, and widely has been used in many things, like this Georgian townhouse conversion and so on, is to start from the point, really, of not designing to take the maximum sort of standard type of working load. So the standard office floor load for office buildings nowadays is 5 kilonewtons per square metre that people generally aim at, which is actually, when you look at it, really quite a densely packed use and allows for heavy file storage and things like that, which nowadays people don't tend to need to have. 

So we really started an alternative approach, with the engineers, of looking at how to combat that, and the first start really is to say, 'Right, we're not going to achieve 5 kilonewtons. We're going to have to manage the floor load and look at something like 2.5 [indistinct] and impose load 2.5 kilonewtons per square metre, and manage the building accordingly.' It has implications for how you continue to let and manage and get commercial use out of the building. But that really was the only way forward in this case. 

And then looking at the overall structural approach, we had a major problem with both the beams and the columns not being up to that necessary factor of safety and load-bearing capacity. The simple way to do it, and this was an approach taken in the early years of the project, was actually to introduce pretty much a sort of internal steel frame right across the building, with clear spanning steels right the way across from wall to wall from the brick external walls, one to the other, and making the columns somewhat redundant. That though, we came to realise, was going to introduce sort of major impact in the building, would have raised all the floor heights throughout, would have had a huge impact, and also was going to be extremely costly. The methodology for installing it got more and more difficult as we went into it. 

So eventually, we came up with a much more conservation-led approach, which was really looking then at quite a sort of complex whole palette of different approaches, looking at how we were going to target individual elements, really, and supply strength where it was needed, rather than the overall approach. So here you can see the failure is particularly on the ground floor, the columns, factor of safety there as the weight gets worse towards the ground floor, and the central columns on the first floor. Some of the others are not so bad. So we then move forward this, and this was the design approach which we'd been pursuing, where we've introduced just six new columns on the ground floor, the principal public floor, so we wanted to minimise the intervention there. Major intervention will use a steel, grid structure on the first floor. Over on the right, that's our fairly straight forward detail for tying up these cracked beam ends into a reinforced floor screen, and that gives us then this approach.  

Here, you can see on this slide, the red parts, we have ground-floor columns, first-floor grid here, some further columns just in the first floor. But above that level and particularly on our prime floors, like the third and fourth floors, we're then able to dispense with everything except some tie rods. There's a whole lot of tie rods that have gone in. That's part of getting the whole structural action across the whole building. You can see here the huge array of steels that are going into the first floor. That obviously is raising the first floor, but that actually we were able to accommodate without too much difficulty. 

And then on the ground floor, we have here-- and this is one of the new columns going in. There's a major structural work needed in the floors here, but just six columns. So it's very much a targeted approach to supply strength where it's needed, not looking at interfering really with the original cast iron structure by bolting things to it or putting resin repairs to it or whatever, but actually just applying extra strength where needed and getting the most out of the major floor plate action to create a really strong diaphragm with box layers all the way up. 

So I think that's the very quick run-through of our major structural problems. I'm going to move on now to project management stages, talk about a few issues, and I think, Kate, you were going to come in again at this point. 

Kate [42:03] Yeah, thanks for that, Nick. So some really good practical illustrations of the design approach and the technical structural issues. Remember if you do have any questions, please do put them in the chat, but start with the capital letter Q so that we can draw them out to cover at the end.  

So as we're now at the final year of the five-year programme, I'm sure many people are wondering, how are we doing on time and budget? Nick? 

Nick [42:36] Yes, well it's a major undertaking, really. We were doing pretty well, really, until the beginning part of this year when Covid struck, and that's obviously had its effect on things as well as everything else – a few other problems piling up – but actually overall, it has to be said, we had a £25 million project overall. We caught up quite a lot of time and budget early on because we'd done such a lot of preparation and careful work to address some of the early problems, and that gave us a good start, so pretty much overall, we're just beginning to creep 1% or so over budget now, and we're running now a few months behind programme with the Covid delays. But generally, I think we're not doing too badly. 

Kate [43:27] OK, and your role being the project manager, can you just talk us through some of these key issues that you've drawn out? 

Nick [43:34] Yes, I'm just going to very quickly flag up a few things here. We've got the sort of time, cost, quality triangle there, which is a well-known thing in terms of all projects, and you need to judge which of those are the most important to you. As you're told at the beginning, you want all three of those, of course, but often you can have two but one of them has to slip somewhat. And in grade I historic buildings that it's the quality and the care of that historic building that comes foremost, and the cost obviously can be a major sort of problem in that if you've got a fixed budget, that's it, in which case you have to adjust the scope, and the time, sometimes, is the one that has to give way. So there we go. 

Just to pick up on these bullet points very quickly. The surveys and investigation is certainly, as we always stress in Historic England, a key part of getting any successful historic building work underway, really. The early investment in measured surveys, timber decay surveys are the structural surveys and historic investigation. And something that that then understanding and significance-- the important thing about that is understanding the problems that you have and also their place in the historic significance of the building. What's the most important parts of the building? Where are changes and impacts acceptable? Where are they not? Developing that understanding, absolutely core, really. 

Procurement in contracts. The nuts and bolts of building. With this project, we've been on a bit of a rollercoaster in that earlier on, because there was pressure to get the project underway, there was pressure to do it with a design and build contract without, necessarily, all the sort of groundwork of things. That then led us into some difficult territory. We had to reign back from that, and we then decided to reprogramme, take our time, and actually then went out with a very, very thoroughly old-fashioned bill of quantities approach, which has set us up, actually, very soundly with the level of cost control and budget control that we have. So that's something that-- Generally, most of the projects that I've been involved with have been run on that basis. 

Just picking out one or two other items – quality-price selection is a key aspect, really, of any tendering process in the public sector and for any grant-aided project. You obviously have to go through a competitive tendering process. When I first start in this business in the public sector, you were forced to take the lowest price tender, no questions at all. Thank goodness we left that behind some time ago, and it is a vital part of any good tendering process to make sure you've got a really good quality-price selection so that you're not just getting driven down always to the lowest price. What you want is value for money. 

Enabling works and site trials is sort of building on from your surveys and investigations, and I'll come on to say a little bit more about that because in this case, that's been quite a key part of establishing a successful way forward for some of our most complex problems. Alongside that goes programme and phasing. I suppose one of the key lessons you learn as a project manager on historic buildings over the years is not to get railroaded into signing up to an impossible-to-achieve completion date. Very early on, there's all sorts of pressures to do that very often, and you need to take a long hard look at that and argue that time is needed to do these things properly. Alongside that, often it's very worthwhile, as we've found, to build in different phases of the project. That gives you the flexibility to achieve things, to move forward with certain information on the phase that you're on and be building up a level of certainty and information on future phases. 

And throughout it, of course, also the cost and change control making sure that your project is firmly got a grip on all aspects and that the budget is staying online and any changes sort of-- It's easy to get project creep and project scope getting out of control, and you need a firm grip. But you need to be flexible enough to see where those are needed and to make changes where they definitely add value, but need to be thought through. I think, was it-- Kate, I'm back to you, I think, just in terms of that quick run-through. 

Kate 48:11 Yes, yes. So we've taken the change, haven't we, when preparing for this webinar to just reflect a little bit, and certainly a theme that's coming out from what you're saying is that there was a lot of early upfront work, and that was really critical. And I think sometimes that can be quite hard to explain to persuade clients that that's needed or the benefits of that. Often, people are quite keen to get going quite quickly, as you say, so it's really good to have these practical examples that you're sharing with us.  

So looking at those points there, did you want to say a bit more about some of those, with an example. 

Nick [49:05] So I think the one I particularly want to pick out here, to me the most important thing in terms of setting the right way forward for any historic building, is sort of the core understanding and significance of the building, understanding what's wrong with it, what you need to change with it and how that impacts on its character and making sure that those are carefully targeted. But also working out the methodology of how that can be done, and this was certainly the case with this particular problem that we had on the Shrewsbury Flaxmill Maltings. 

Apart from the iron frame problems themselves, one of the most complex structural problems we actually had was on the main external brick walls of the building, which it turned out from quite a lot of the survey investigation work, had at every floor level across the building, so across here, here, here, here and here all the way up five floors of it, a timber ring beam that went from one end all the way around the building, into which the original iron frame had actually been bolted – rather peculiar. That in the way of timber had got damp over the years and had failed, and what you see on the right here is where the core of the wall-- basically nice big thick wall, often, say, two bricks thick, 500 mil. or so thick, but in the centre of it a great deal of that taken up by timber and voids and therefore the outer leaf buckling away. 

What had to be done to prevent the building collapsing had been to put up this scaffolding. What you see on the main slide here is not just an access scaffolding for works and a temporary roof, but actually a scaffolding which is actually holding the building together. There are ties running through the building at every [indistinct]. There are pressure points, as you see on the pad down here, all the way along the building, stopping the walls from bursting apart. 

So our problem was, how were we going to get the whole of that timber out and replace it with something sound? And we eventually decided we needed to develop a whole methodology of this. We sort of worked out it could be done in design terms, but how were we going to build it in terms of buildability. And eventually, we decided the only way to do this was to carry out a full trial repair of one bay. We actually carried out a sort of small enabling works contract, a whole repair on one bay, as you see here, developing the technique, opening up the windows, removing the timber. It was about a 16-step methodology, and having done that, we could actually, then, go out to tender with that scheme on a firm base. And from there, actually, we were able to grab both this sort of viability of taking the project forward. Some people had thought you would have to take the whole building down and re-erect it again in order to come over this problem. But that was sort of an investment in really tackling the problem, understanding it and getting to grips with it and trials enabling works was what resolved it for us there. 

So just wanted, now, to move through into some last couple of sections of the talk. Sorry, time's running on a bit, but we'll keep going. This is looking at just some of the M&E issues on the building – drawings from our M&E consultants E3 – and looking at fairly straightforward stuff, some of this, in that we've got zones of the building where we've got the main plant room cores. At the other end, we have these engine house, which we were able to use for that. We've already said how we're using the kiln for the vertical lifts, and similarly, for our services distribution, we're looking at a fairly simple horizontal circulation, and then these vertical risers at key points, one here and one here, at either end of the building. As often with industrial buildings, we don't have many voids or whatever. We have no voids in the main mill floors, so we're looking for a fairly clean approach of surface-fixed, clean, functional and efficient approach to services. 

Moving on, just to mention that as part of this, we are fitting some internal wall insulation, though it has to be said, only sort of the less vital parts of the building in some of the engine houses and service cores. There's been quite an issue, as many of you have been aware, about internal wall insulation and that developing into interstitial condensation. And as it happens, Historic England has had quite a major programme of trials and lab work on that, and one of the sites where these lab trials were done for quite a number of years while the Shrewsbury Flaxmill Maltings was waiting to happen is in one of the engine houses here. So this lab room that you see here, as we used to call it, is one of the trials where we were testing wood fibre insulation as against plastic foam insulation to see what happened in terms of condensation. Lots of detail on that available on the website. I think Alice is adding the links there, so do follow that up if you're interested. 

Another aspect and a key part, really, of the approach to M&E side and heating systems and so on has been the approach to natural ventilation, and part of the key decision about the windows and the particular pattern of windows that we adopted with this tripartite thing was that we wanted to move away from what had been thought. We would have to have air-conditioning to a naturally ventilated building. Good plan with Covid the way it's gone. And we've got these windows which have two opening lights through the [indistinct] centre. Our M&E engineers and others then have had to devise a system whereby we can put partitions into the building but maintain that through ventilation, and that means we've had to do some quite clever stuff with these sort of things with a ventilation route with sound attenuation so that we can have partitions and sound, acoustics, while still maintaining that. 

So let's see. Another side of it, though, that we've actually been able to take on with the building, this wasn't the plan earlier on, but quite some time back we investigated whether we could manage alternative energy sources, and we investigated biomass but eventually decided because of the cost constraints, we moved back down to having to rely on sort of main gas as our principal heating source. Then as we were progressing and as the technology was developing and we had a bit of capacity within the budget, we made some savings on the early structural repairs. We actually decided to commit to doing a ground-source heat pump insulation as our critical piece of the energy source supplies. So we're now looking at this as providing 2/3 of our heat. We're still needing the gas because of the intensive use, so about a third of our energy's going to still come from the gas boilers. 

Just wanted, really, to pick out a few things which I've certainly learned about ground-source heat pumps. It's very much new technology, and we think this is probably one of the earlier buildings to have a ground-source heat pump, a historic building of this scale and size as its principal energy source, so it's a great thing to be showing the way forward on. A few things just to be aware of. You do need a sort of footprint of ground to be able to put all the boreholes that you're going to have. We're going to have-- The plan is to have ten boreholes, which are going to be in this zone here. Fortunately, we have this area of ground which we've reserved as a sort of open space because it was the line of the former canal, and so we're using that and the towpath beside it for our place of our boreholes for the ground-source heat pump. 

The other thing you need to have is rather larger plant rooms, so we've lost part of one of our meeting rooms to become a plant room. This isn't it yet. It's not in build yet. We're just about to start on this operation. And another thing to be aware of is that because of the sort of technology and the way that it works with extracting the heat from the ground, we've got ten boreholes going down 187 metres is the current [land?] there. Due to start this in the next few weeks. It'll be interesting to see on site. And they then provide heated water which doesn't reach the same hot temperature as it would from the gas boiler through the condensed heat pump apparatus. So the impact really in terms of planning is that it's ideal for under floor heating, where you have buried pipes within a floor screed and can use fairly relatively low water for your heating temperature. Not so good for radiators, and we've had to upscale all of our radiators. We have underfloor heating on the ground floor in the flax mill, but the radiators, we've had to considerably bulk up the sizes of that. 

So that's it about M&E's services. I think, yes, you were going to come in at that point weren't you, Kate? 

Kate [59:17] Yeah, just on the low- and zero-carbon technologies, and I know we've always had lots of questions about that, haven't we, when we've been on site, and I think there were some coming through in the chat as well. It's a really interesting area. Just to flag up a couple of things that people might want to delve into if they want to go a bit deeper. So in a previous webinar, our colleagues covered low-carbon heat sources, and I definitely recommend that to you. It does cover the Shrewsbury Flaxmill as a case study, and there's other case studies in there as well. Yep, I've already got the link up there for you, so that's great. 

And then Historic England guidance, following this whole building approach, which is the approach that you've taken there. Really, really, these are our top downloads from our website, always the energy efficiency issues. And also of interest, if people want to try out the whole building approach, there's a new survey tool that's coming through from the STBA that will be a template that you can use on your projects, and it'll be digitised, available on tablets. So if you keep an eye on the STBA website, you can have a go and try that tool. And also, again, because we get so many questions about these things, there's a webinar coming up at the end of Jan, beginning of Feb, on energy efficiency, retro fit, traditional buildings, policy and research – an update. It's a two parter, that one, so yeah, definitely a lot of things available there if you want to find out more. 

So yeah, we're just moving on to the final section of the presentation, so back to Nick. 

Nick [01:01:20] OK, just a couple more things very quickly to pick out briefly. Bats in historic buildings. Anyone who's run a project on historic buildings will no doubt have encountered that. They are a major issue nowadays, protected species and much under threat for their habitat, something that we need very much to look after when we're doing work on historic buildings. Here at the flax mill, and quite a number of projects I've run and many others, they've been one of the key determinants in terms of the programme, when you can and can't do things, stripping off roofs and so on. Again, that early work in investigation survey, getting a Defra licence absolutely vital, because it does absolutely dictate the programme. 

Here, this is just looking at a fairly standard set of sort of-- this was alternative provision within another building on site, which we set up to be a major bat centre while we were taking roofs off other buildings, the apprentice house with fairly standard things in terms of bat access points, bat roosting points, and this at the bottom right here is the bat heated roost, which we've provided in some instances there. But more extraordinarily perhaps at the flax mill because of the size of the buildings and the fact that we really want some of the buildings to not have this bat constraint to open up other uses, we've actually, as part of the whole strategy, had to build a whole new-build bat house. We have a corner of the site where the railway junction used to come into the site, not usable for other things, and here we've built a bat house, a brand-new bat house, which has two different halves to it, one that's sort of buried in the ground and has a turf roof and so on that is simulating cellar light conditions for the sort of winter use by bats and one over here, which is more like a roof space, which has perhaps for the summer use and maternity [indistinct]. We have pipistrelle, brown long-eared and also the much rarer lesser horseshoe bat on this site, so that's part of what we've been doing there. 

And then I think the last one just to flag up. Back to history and archaeology again, really, and again back to planning ahead, understanding historic significance and making way for such a sort of major intervention that is need on a project of this scale. That's our 1855 plan once again, and what we knew from that was that we had here a very large structure of the boiler house chimney, which has been built in the 1840s. We knew about that from plan, but it was actually all covered up, so we decided to-- A year before we needed to do anything, we took forward a major excavation on that site, did all of the recording on that and so on, discovered where it's going to go, and meant that we could then target this sort of area, having recorded it for where our major drainage, as you see on the right-hand slide, was going to go through, because we've got some major deep drains and a whole lot of other services which we have to run through here. The base is now going to be displayed as part of the visitors' eye because it's a quite exciting lost feature. 

So it sort of brings it full circle, really, in terms of the way that understanding the site and making time to do that really is critical so that when, as we had earlier this year, we've got sort of major diggers and activity coming through here, they're able to plough throw here having done all the archaeology a year before. OK, and I think that was the last slide, so we're going to come onto any questions, really. Sorry, we've just gone a few minutes over, I think, but hopefully there's some of you here with a bit of time, and we'll try pick up some of your questions. Those last views are a current aerial view of the whole site, and the architects' view of how it's going to be in the future. 

Are you going to take us forward on this, Alice, in terms of which [indistinct] to pick up? 

Alice [01:05:47] Hi, Nick. Hi, everybody. Thank you so much for attending today. Thanks to Nick and Kate for an excellent presentation. We do have quite a few questions, but they're not quite visible at the moment. We also have run out of time, so I think what's best is that, Nick, we will email you the questions and you can get back to the individuals, will be an easier way to go rather than keeping everybody a bit longer. So that will probably be the easiest way to go, so I would like to say thank you to Kate and Nick for a really interesting presentation. Thank you for all the attendees. 

It's been great to have so many of you. I've got a few questions. Yes, Harry. I've got your questions and I will send that forward, so please, please be aware that I have those questions and we will go through the transcripts to make sure that we can get the questions answered by the relevant people. So thanks again, apologies for overrunning and we will see you at the next Technical Tuesday, hopefully. I will also put up the web link for those of you who want to see the webinar list and any advice and guidance. 

Nick [01:07:03] OK, well thanks very much to everyone. Sorry we didn't have time for a bit more of a discussion question, but I think there's lots of interesting questions come in, though I think some of them, the earlier questions, we may have picked up on some of the energy conservation issues. Yeah, so I think just to pick it up while we're talking, because it was a key part of the energy strategy. I think Harry it was who asked about how we were going to heat the kiln. The answer is, guess what? We're not going to heat the kiln. That's just the atrium space. That's like your sort of St Pancras Railway Station space where you're walking through and keeping your coat on. There's a reception to one side of it, glazed screen that is heated, so...