ARC Guitars Posted January 8 Share Posted January 8 Hi all - first proper post on here so apologies if the answers to this question are out there and I’ve failed to find them!! I’m trying to work out if we should change our building control officer as the one we’ve got hasn't been super helpful. But then I’ve not done a self build before so worry it might be me not understanding what they're allowed to do! Backing up a bit: we’re nearing the end of the detailed design phase of a self-build house, and appointed a registered building control approval firm (one of the fairly big ones) a while ago. They moved us from their original chap (who was quite helpful) to a new guy about 6 months ago, as the original was too busy and they’d changed the areas they cover. The new guy’s completed a plan check for us and there are a couple of areas we need to address, but he says he can't offer any advice on how to address them. Is this right?! I’d always understood that your BCO should be able to advise you on what they want to see / how to comply. An example: the plan check report said “Part B… The following details do not appear to achieve compliance: Alternative exits; Inner rooms.” We went through the regs and concluded it was just our proposed snug that wasn’t compliant, so we asked if that was the case (it was) and if he could offer any advice on achieving compliance, to which he said he wasn’t allowed. (We think we’ve now got a solution to this issue, although we’ve only got a one word answer from him as to whether it now meets the regs so I’m not totally confident!). Similarly, he’s asked for evidence that the external walls meet the required fire resistance (they should as it’s a standard construction), but when I asked for advice on how to demonstrate this, he again said he’s not allowed to help. I’m worried we’re stuck in this cycle where he says something cryptic about a thing not being compliant, then we spend ages working out what he means, then we have to propose loads of solutions until we stumble on one that he’s ok with. Seems pretty inefficient and likely to leave us with some solutions that aren’t the most sensible / cost effective. It’s worth saying he’s also quite slow to respond on emails if he replies at all, and when we rang to chase him, his reply was “I’ll try to squeeze you in” which I find a little annoying since we’re paying for this service!!! So have I misunderstood how much help / advice a BCO can give? Or is it worth us sucking up the cost of switching to another firm before we start the build? Grateful for any advice!! Link to comment Share on other sites More sharing options...
kandgmitchell Posted January 8 Share Posted January 8 This has all come about after the Building Safety Act. These guys are individually registered building inspectors now with the emphasis on "inspector". They are being told they are not designers as that path leads to liabilities....... I would agree that doesn't help you but to be fair the regulations now expect a designer to be competant so you should be leaning on a design professional if you are unsure about the regulations. When you say your walls are of a standard construction - what is "standard"? It's difficult to judge what level of information you are giving this person, if it's little more than planning drawings then a plans check does result in some fairly vague queries I'm afraid because there's not much to go on. In the past I've seen some house photo's and a land registry location plan submitted as an application for converting the loft of a listed, converted barn to a habitable room. The plan check response was suitably sparse in response I can tell you..... 1 Link to comment Share on other sites More sharing options...
ARC Guitars Posted January 8 Author Share Posted January 8 (edited) Ah that's helpful - thank you. We wondered if the rules change was behind this. On the drawings - the level of detail is pretty high. There are now over a hundred drawings right down to the specifics of all the build ups and junctions so there's no ambiguity about what we're proposing. It's a timber frame from one of the big factory framers with 140mm studs and 9mm OSB sheathing, mineral wool fill and 50mm PIR on the inside. There's a 35mm service cavity then plasterboard and plaster inside. Outside is 50mm cavity then 20mm timber cladding on two elevations, and a 145mm cavity with corrugated box profile steel sheets on the other two. (The cavity's so big on the steel sides because we've got hidden gutters at the top and the framers recommended making the cavity bigger rather than notching out the top corner of their frame.) Edited January 8 by ARC Guitars Link to comment Share on other sites More sharing options...
kandgmitchell Posted January 8 Share Posted January 8 So how close to the boundaries are those walls? 1 Link to comment Share on other sites More sharing options...
ARC Guitars Posted January 8 Author Share Posted January 8 North 4m South 2.1m East about 44m West 6.1m We're under the protected areas allowed on the North and South so long as it's just the glazing that counts. It's the North and South elevations that have the steel cladding. Link to comment Share on other sites More sharing options...
kandgmitchell Posted January 8 Share Posted January 8 Unprotected areas - they don't have the required fire resistance. No hope of either the north or south walls facing a road, river, canal or like? The relevant boundary then moves out to the centre of that feature and you may find the whole face may be UA. Wishful thinking probably. First stop would be the steel cladding manufacturer (or at least the one with the most technical stuff on their website). Look to see if they have any fire test reports for boundary wall situations, go to your timber frame supplier and ask them, - usually with a bit of hunting around you can find a certified detail that you can wave under BC's nose even if you have to add say a mineral cement board behind the steel to get a match. 1 Link to comment Share on other sites More sharing options...
ARC Guitars Posted January 8 Author Share Posted January 8 That's good advice - thank you! Link to comment Share on other sites More sharing options...
Gordo Posted January 10 Share Posted January 10 (edited) Don’t quote me but I think you need 1/2 hour fire resistance both sides of external wall. I assume that % windows are within that allowed relative to the distances from relevant boundary. Otherwise the BC officer would have mentioned concerns about % unprotected areas. So you just need to demonstrate that your makeup achieve 1/2 hr FR on both sides using manufacturers declarations such as the British Gypsum whit book Edited January 10 by Gordo Link to comment Share on other sites More sharing options...
Alan Ambrose Posted January 10 Share Posted January 10 I’ve seen this mentioned a few times before, but don’t get how anyone builds a timber frame and timber clad house? Like a Scottish long house, for example, or anything from Heb Homes. Link to comment Share on other sites More sharing options...
Gordo Posted January 10 Share Posted January 10 (edited) 51 minutes ago, Alan Ambrose said: but don’t get how anyone builds a timber frame and timber clad house? It’s not an issue if the wall is far enough away from boundaries and not supporting a fire resistant element. Edited January 10 by Gordo Link to comment Share on other sites More sharing options...
Gus Potter Posted January 10 Share Posted January 10 On 08/01/2025 at 10:02, ARC Guitars said: Hi all - first proper post on here so apologies if the answers to this question are out there and I’ve failed to find them!! Welcome to the land of BH! 34 minutes ago, Alan Ambrose said: I’ve seen this mentioned a few times before, but don’t get how anyone builds a timber frame and timber clad house? Like a Scottish long house, for example, or anything from Heb Homes. It's doable! On 08/01/2025 at 10:02, ARC Guitars said: I’m worried we’re stuck in this cycle where he says something cryptic about a thing not being compliant, then we spend ages working out what he means, Ah! If it's any help I do this as a day job. The poor performance, basic lack of knowledge about the construction / design industry, professional standards in terms of communication from say Planners and BC is astounding at times. In mitigation they are starved of funds so there is no time for them to learn these basic skills. On 08/01/2025 at 10:49, kandgmitchell said: This has all come about after the Building Safety Act. These guys are individually registered building inspectors now with the emphasis on "inspector". They are being told they are not designers as that path leads to liabilities.... And the liabilities are big! My PI (Professional Indemnity) insurer has a long list of questions about just what I'm designing in terms of fire protection. They need to understand how much risk I'm taking on and their exposure. In general BC officers just don't hold the required PI cover these days. Many Architect's are nervious.. and rightly so as fire protection is linked to structural design. 56 minutes ago, Alan Ambrose said: I’ve seen this mentioned a few times before, but don’t get how anyone builds a timber frame and timber clad house? Like a Scottish long house, for example, or anything from Heb Homes. It might kind of work like this for Heb Homes. But they may be able to shed more light on this. It works for me. Here is a rough summary of the things we need to think about when building something near a boundary. In Scotland / kind of rest of UK. If something is closer than 1.0m from the boundary we need to stop flames and sparks from jumping over the boundary and setting light to the house next door. We call this fire integrity. For example if you have steel cladding then if the seams of the panels come apart then sparks and flames come out which can jump the boundary. Another part is what we call "fire resistance. Here we want to stop the wall from heating up so it radiates heat, like an electric fire too close to the bed. The fire intergrity and resistance are then combined to give you the overall fire rating of say a wall. That's a rough summary. If more than 1.0 m it gets easier in terms of complaince. Some structural design stuff relating to fire: The easy way to explain (laymans terms) this is that we need to make sure the structure is protected enough so you can get out if a fire starts. Hence the 15 min and 30 min you see. But we also need to make sure the structure does not fall on the Fire Brigade. Many of these folk have lost their lives trying to protect badly designed properties and industrial buildings. On 08/01/2025 at 11:03, ARC Guitars said: and a 145mm cavity with corrugated box profile steel sheets on the other two. (The cavity's so big on the steel sides because we've got hidden gutters at the top and the framers recommended making the cavity bigger rather than notching out the top corner of their frame.) Here lies one big issue. There is no standard detail for this. I do a lot of refurbs / conversions etc and and many of these are timber frame / light weight construction. I adopt this approach as often I get to reuse existing founds and so on. When adding an extra storey to a building I often look at how much load I can remove first and then see what I can add back in without having to say strengthen the existing founds. But this leads to odd sized cavities (we are building off an old cavity wall maybe) that we need to ventilate. But we also need to fire protect the wall panels.. often called fire stopping. It the cavity is fairly normal 50 - 60mm I may use an intumescent fire stop strip like say TENMAT which gives me the ventilation but also stops fire spread. But this has limitations. If the cavity is say 145mm then we need to block a bit of that off ( say with good solid timber ) but still keep enough ventilation for day to day perfomance. I'm just touching on some of the complexity. BC just can't give you this kind of advice / take liability for the amount of money you are probably paying them. 1 Link to comment Share on other sites More sharing options...
LnP Posted January 11 Share Posted January 11 @Gus Potter since it's timber frame, what are your thoughts about needing to have the structure assessed against the STA Design guide to separating distances during construction? Link to comment Share on other sites More sharing options...
saveasteading Posted January 11 Share Posted January 11 @LnP thanks for that link. I was not aware of this document so will read it thoroughly later. It's a great example of what I was going to say which is basically...it is complicated and ultra important. i have designed and built buildings for decades. Hundreds. I thought I was expert on fire risk. One of our steel buildings was exposed to extreme fire and the fire chief said he'd never seen such good resistance. And yet, when I went on a 3 day intensive course I learnt much more. Professors study nothing else, and what we see in the regulations is a summary. Building inspectors rightly want to see proven constructions as any variation creates a risk. That can be frustrating when you have a special circumstance of a 'great idea' but safety must come first. Why should they accept a variation. Even so, we find that kingspan and celotex ( do i say allegedly still?) cheated their fire tests. @ARC GuitarsWhat are you paying the bco? Typically about £1000 for the whole project. That is what 4 days of a tradesperson will cost, or 1 day max of a professional designer. The bco is not your designer. On the positive side. A timber housing estate here won't burn like in Los Angeles. Timber needs air flow if it is to blaze and spread. Working to the regulations prevents that. 2 Link to comment Share on other sites More sharing options...
Gus Potter Posted Sunday at 23:25 Share Posted Sunday at 23:25 (edited) On 11/01/2025 at 00:17, LnP said: since it's timber frame, what are your thoughts about needing to have the structure assessed against the STA Design guide to separating distances during construction? What a cracking question! Talk about putting folk on the spot! Forgive me if I don't deal with some detail or give a definitive answer. One main reason is I use my own name and while my PI insurance covers me to write on a public forum (give unpaid advice).. it's not open ended. I make some comment later that may help the self builder / folk extending say. It's good guidance. The following is some general comment for discussion purposes only. The guidance adds to / provides a methodology to support some of the things we have been doing for a long time anyway. The recent changes in the regs formalise this and aim to hold folk to account for their design, contractor to their duties and say the duty of a self builder, even someone doing and extension in timber frame. I support anything that will keep folk safe. The document is a guidance document. Many of the clauses in the Buildings regs, British Standards, Eurocodes, product manufacturer's guidance / data etc are.. guidance. But if you choose not to follow this and something goes wrong then you can find yourself on a sticky wicket as the onus falls on you, as often you need to prove that what you have done is equal to or better than the guidance. There are times when SE's need to go back to first principles and develop stuff from scratch. This crops up a lot when renovating, upgrading old buildings and say converting farm buildings to domestic use. You get funny sized cavities / flexible steel frames / old mortar and all sorts. Generally once we get into the "higher risk" building category.. could be a flamible house next door, a TF of say 3 storeys or more, close to an old folks home, a block of flats, a fuel station etc then the bells start ringing. At the concept design stage we would pick this sort of thing up.. good designers spot this kind of thing. To go back a bit let's look at what we are trying to achieve. The following list is not comprehensive and I've tried to put things in some kind of sensible order. 1/ We want everyone who works on the site or attends site to go home safely at the end of the day. It's basic Health and Safety stuff. Everyone on site needs to know what to do and where the exits are if a fire breaks out. This includes anyone working on scaffolding / mast climbers or the like. There is plenty information readily available on this from the HSE and other knowledge bases. One key point more applicable now is that a Client should aside enough in their budget to enable a contractor to comply with the current HSE regs and stipulations from the designer regarding say construction sequence. It's always been there under CDM but hidden to some extent from the domestic Client ( self builder / extender) For all on BH. When getting prices from builders it's worth getting them to itemise out a sum for safety complicance on site. This lets eveyone see that you are taking safety seriously from the outset. 2/ OK say there is a fire and everyone is off site safely. The fire brigade turn up. They need to be kept safe also. You can't have a structure suddenly collapsing on them. Now we are getting into the design / planning of the method of construction and sequence. As a designer when faced with this I would introduce this at an early stage to a Client.. this is usually an expansion of the explanation about fire boundary conditions that apply post completion. See my previousish posts. 3/ OK say we want to do a self build in TF that during contruction poses a risk to a neighbouring building? The Building regs talk about fire boundary conditions.. you can have one even if there is no house next door! Most of the time we know that the construction phase is relatively short cf the common 50 year design life of a house and can see if there is a structure next door or know if one is planned during the construction phase. 4/ Well we can look at the STA guidance for fire during the construction phase, refer to other stuff we are aware of and importanly apply common sense. Then find that we either can't have a TF under the STA guidance or it is going to become too costly to do a self build of say 2 storeys. 5/ Now we need to go back an look at the risks of the particular project. No project is without risk so what can we do? 6/ For me I look at how could a fire start. Again much of this is covered in the HSE regs and guidance on fire safety on site. But basics are no smoking, no hot work, no using a grinder that causes sparks.. no hot site lighting and managing material handling / storage that can add to the fire load (the fuel for a fire) the basic stuff. I look at my design.. Have I / will design something that adds risk? What is not so well covered is site security (your location) and the way you conduct your personal business! A few years ago we had a big problem up my neck of the woods with the criminal fraternity washing money in site security. Bills were not paid and a lot of TFs went on fire at the weekend / at night. Mind you the poor spark got the blame some of the time for dodgy site security electrics! A big risk is theft from containers. Folk use burning gear to cut the container open.. keep your container away from the house if you can. 7/ If we can't get the risk down enough (say 24 hour site security, a fire watch at critical times etc) we may then say let's put up a few TF panels and get the brick cladding up straight away to fire stop level. We may need to get some cross walls in to act as lateral support to the external walls and worst case provide some temporary protection. In summary it's about looking at the risks and mitigating them to an acceptable level. The question is what is acceptable! For me part of the foundation of acceptible is a Client that will engage / discuss, that is my starting point, rather than just "seeing me" as an unwanted expense, a route to getting BC approval and then going off an going their own thing.. the new regs are intended to put a stop to this in some ways. Some may say it's jobs for the boys! But if you get you designer in early and just talk through the job it can lead to lots of other savings and ideas that can easily offset the professional design fee. To exagerate to make a point. In item (2) I point out that we don't want the structure to collapse on the fire brigade. The structure is connected to the foundations and these can provide rotational support to a wall subject to fire @saveasteading has written lots about encastre support / wall and steel frame base fixity and you can find out more about this if you look at his posts. So now we talk about your founds / floor joist span, type etc etc.. and this leads to holistic design and cost savings. Some clouds have a silver lining even if you have to stump up a bit more cash at the outset in terms of design fees. Over my working life I've seen two fatalites and one serious injury on site (loss of a limb). Two were preventable, one was a freek of nature to some extent. I myself got briefly trapped in a tight solum space when I was a young builder (before I became an SE) and set fire to the floor above when using a gas plumbing torch.. I could see the flames above and that rapid crawl to get out stays with me to this day, worst still there were kids in the house so it was just not myself I was looking after! Uncontrolled fire is an awful thing. That's it for now @LnP Edited Sunday at 23:55 by Gus Potter 2 2 Link to comment Share on other sites More sharing options...
ARC Guitars Posted Wednesday at 14:56 Author Share Posted Wednesday at 14:56 Hey all - this is all super helpful. Sorry to have gone a bit quiet! @saveasteading - we're paying about £1500 in total... As far as I can tell at the moment I'm ok on fire resistance and integrity as we're at least 2m from boundaries on all sides and the BCO hasn't raised any issues. But his comms aren't great so I'm not totally confident it's resolved! The 145mm cavity is worrying me a bit as it's not standard as you say @Gus Potter. In some ways I wish I'd stuck to my guns with the timber framer and kept it as a smaller cavity. I think they're probably just looking for what's easiest for them rather than necessarily best overall. But we are where we are now! My cunning plan for cavity barriers was to mount an intumescent strip onto a chunky timber as you say, leaving a gap for ventilation, and then to install some fire proof foam stuff into the corrugations on the steel. If the BCO wants evidence that this arrangement will be ok, how would I go about getting that? Am worrying about having to have some expensive testing done or something! Link to comment Share on other sites More sharing options...
Alan Ambrose Posted Wednesday at 15:24 Share Posted Wednesday at 15:24 Bug him until it's easier to answer your question that keep fielding your calls? @LnP - thanks, that doc looks great - 7 different kinds of timber frame re fire already Link to comment Share on other sites More sharing options...
Gordo Posted Wednesday at 17:13 Share Posted Wednesday at 17:13 (edited) 2 hours ago, ARC Guitars said: install some fire proof foam stuff into the corrugations on the steel Don’t think BC would like this as fire foam is often limited to a small gap (maybe 1/2 inch) maybe cladding manufacturer could recommend suitable proprietary product or make up your own generic cavity barrier from suitable FR materials. See an extract from N. Ireland Guidance Document (English AD will be similar). Maybe compression fit mineral wool between a 38x38mm min. Batten and cladding or cement board/steel cut to follow profile and fixed to similar batten. Best solution may be If the intumescent strip cavity barrier is located close enough to cladding, it could fill the gap in a fire, while allowing for drainage and ventilation to rear of cladding. Check product details for max gap. Awkward junction to fill Edited Wednesday at 17:23 by Gordo Link to comment Share on other sites More sharing options...
LnP Posted Wednesday at 21:21 Share Posted Wednesday at 21:21 On 12/01/2025 at 23:25, Gus Potter said: 4/ Well we can look at the STA guidance for fire during the construction phase, refer to other stuff we are aware of and importanly apply common sense. Then find that we either can't have a TF under the STA guidance or it is going to become too costly to do a self build of say 2 storeys @Gus Potter Thanks for your thoughtful reply. Thinking about this point though... is it possible the fire prevention measures could make TF too expensive?. Would it be that difficult to get to a Category C1 Fire spread resistant frame? Maybe just replace the OSB sheathing on the wall facing the neighbours with a e.g. cement board or similar? Even getting to a Category C2, which means you don't need any separation, just means not cutting out the window apertures in the sheathing until the external cladding is up. Obviously depends on whether the cement board has the necessary structural strength. If you've thought about this at the design stage, perhaps the extra cost is just the difference in price between the OSB and the cement board? Link to comment Share on other sites More sharing options...
Roger440 Posted Thursday at 13:18 Share Posted Thursday at 13:18 On 08/01/2025 at 10:49, kandgmitchell said: This has all come about after the Building Safety Act. These guys are individually registered building inspectors now with the emphasis on "inspector". They are being told they are not designers as that path leads to liabilities....... I would agree that doesn't help you but to be fair the regulations now expect a designer to be competant so you should be leaning on a design professional if you are unsure about the regulations. When you say your walls are of a standard construction - what is "standard"? It's difficult to judge what level of information you are giving this person, if it's little more than planning drawings then a plans check does result in some fairly vague queries I'm afraid because there's not much to go on. In the past I've seen some house photo's and a land registry location plan submitted as an application for converting the loft of a listed, converted barn to a habitable room. The plan check response was suitably sparse in response I can tell you..... This is interesting stuff, and like the OP we are starting to see the impact of the October 23 changes. It will certainly make life more difficult for someone actually trying to do some or all of the work themselves. Does suggest, that if you have a contract with architect/ designer or whatever, that it probably needs to include a clause that makes satisfying the BCO of your design a key clause. within the cost. Ive not built a house, and, sadly, have accepted i never will. But if you were, if you dont have this, it falls on the owner to keep paying for re-submissions. I guess it will sort out the designers who know their stuff from those who dont! Then the builder just needs to build to the design. I say "just" in jest. We all know how that can go. Sorry ive contributed nothing to resolving the OP's issues. Link to comment Share on other sites More sharing options...
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