Gus Potter

Quick reality check folks. Make things complex on site and you'll often pay for something that never gets delivered by the contractor. Wrapping the bottom of internal columns in Aroegell is daft.. because you need a small quantity (costs a lot) and someone has to go in the van to go and get it! That excercise just to procure the stuff could cost you £150 -300 or more which could pay for a lot of thicker insulation elsewhere at no risk. You may need fire protection so a bit of extra glass wool solves the problem and get you below the 0.7 U back stop value to stop regular condensation. The key thing that a lot of folk seem to be missing here on BH is that you can do a compensatory U value calculation. If you have a steel column poking out inside the house you need to make sure it does not drip with condensation. Again a back stop U value of 0.7 is about right with a vapour barrier to be on the safe side. There is a massive diference between an internal column and a steel column on the external wall in terms of cold bridging. An internal column is founded on the heated dumpling of soil so the heat loss is much less that the basic software is often telling you. You then compensate for the extra heat loss by beafing up other parts of the insulation envelope. But for such a small extra heat loss from an internal column.. it's next to nothing. This is a common sense approach that a lot of folk on BH are missing.

Oh and if you do this you will find that you are falling under the CDM regulations not least. Please spend some time investigating what you're getting yourself into.. hence the percentage fee rates I mention. How well are you insured to do this? It's not just to protect you it's also for your Client in case you get run over by a bus. You have a duty of care and while it sounds great to help folk out when you do so things have to be set up correctly.

To put a bit of an impartial slant on this.. @nod is highly experience, has time and also has a day job and contacts in the construction industry? Now I'm not going to cast stones as I use to be a Contractor and also had plenty of employees and subbies that I could chuck at my own stuff and make the money work. Nods figures are probably achieveable if you are set up this way.. but this is a self build forum and I can tell you (I do this as a day job) that Nods rates are "optomistic". But also Nod works like a fiend seven days a week! Nod has some serious commitement and deserves the reward. But often folk on BH have young kids so you can't do what Nod does. My hat goes off to Nod for commitment but most of my Clients just don't fit into Nod's mould and we need to reach a compromise and the build cost goes upas a consequence.

Given the size of this project and complexity my advice is to diplomatically extracate yourself from this. If you are intent on pursuing then you need to be commanding a fee of somewhere between 8- 12% of the build cost. Set out the deliverables, get paid in stages and get a good QS in right now.

The following I hope gives you a flavour of the design but also the liability that lies with the designer and that, I hope, will help folk on BH get their head around some of the SE type fee costs. Well done @Alan Ambrose for digging out this article. The author takes one of the CPD courses on Eurocode concrete design I have been on and interrogates it in a bit more detail.. and makes a good job of it too! For me this is part of my day job so am familiar with the terms / design calcs etc and how the Euro codes go into more detail and the theory behind it.. such as restraint conditions, ageing, restraint at slab ends.. a long list. But for all on build hub for the critical thing to take away from this is the bit at the end of the article copied below. "Firstly, the design need to be realistic. Blindly throwing reinforcement at it can do more harm than good. Good detailing is particularly important for complex geometries. What’s more important is to try and have simple geometries in the first place". In other words you can have a fab house but keep the underlying structure as simple / stupid and buildable as you can. That drives down cost, reduces risk and lets you spend your cash on the thing you get to see and enjoy. Hiya @SteamyTea If I could I would give you a double cup award.. I've learnt loads from you.. For all there are some folk like Steamy and to do a name check @MikeSharp01 who are fantastic educators. I'll give it a go and try and cover some of the concepts for folk on BH. but excuse the spelling and grammer please! For all the below applies to lots of other things you might do not just basements. Ok take a simple concrete reinforced beam spanning between two walls loaded from above. The bottom of the beam is in tension and the top in compression. Concrete is quite "stiff" which means that under compression is does not compress much. The bottom of the beam is in tension. Concrete is not so good at resisting tension so we introduce steel rebar in the bottom of the beam which has lots of tensile strength and now we have a reinforced concrete beam. But steel is quite stretchy compared with concrete. For it to work the steel rebar needs to be bonded to the concrete at the bottom of the beam. For the beam not to fall down the tensile forces in the top of the beam need to balance the tensile force in the bottom steel rebar. But to achieve the balance the steel needs to stretch first thus we get cracks in the bottom of the beam. The same principles applies to basement walls. Call this behavoir primary cracking. To limit cracking we add more rebar area so the steel does not stretch as much. In other words when we design reinforced concrete we make sure we have enough rebar so it does not fall down.. then check that we are limiting the amount the steel stretches by so we limit cracking. Now it gets complicated. In a reinforced concrete wall we have a large area of concrete that as @Alan Ambrose article points out undergoes a number of "experiences". Concrete goes through a number of phases when you pour it in to say a basement wall. Broadly speaking cement (part of the component in concrete) needs to start getting it's act together within 4 -8 hours ( temperature dependeant) and this is covered in the BS standard for example. This means that the chemical transition gets underway. This causes a lot of heat which makes the concrete expand. After say 24 -48 hours the concrete starts to "bind".. the aggregates, cement any additives and we get what is called plastic shrinckage.. which can be quite a lot.. in other words the concrete is still in quite an excited state for a better word. After a bit of time the concrete starts to dry out and we get what we call drying shinkage. On a raft slab.. say on an EPS raft slab we also get funny behavoir at the slab corners call "curling".. which is basically all of the above having a laugh with us. @SteamyTea The secondary reinforcement is primarily intended to deal with the behavoir of the concrete during the curing and drying out process. It is a bit of a guess but if you look after your concrete for say a month after it's poured you can do a lot to help yourself in terms of getting what you have paid for. Quality of workmanship is key. I've copied below a bit out of one of my specifications that I wrote for a self builder for a floor slab. The idea of this is to provide simple instructions for what you can do on site to address what is a very complex problem. Designer liability: From the above you can see that this is fraught with liability if you are say an SE / designer like me. My PI insurer goes nuts and wants to know exactly how much liability I'm taking on. @Alan Ambrose article deals with Eurocode design which if applied well results in lean and cost effective design.. but it is predicated on all the Contractors etc doing their bit very well.. the construction industry in the Uk is not often up to this standard. So when it goes wrong I'm for example the first easy target. Now folks if want to pay me for taking on that liability then I'm fine with that.. but the only way I can do that is if I come to site often to make sure that the contractor is doing "EXACTLY WHAT I REQUIRE" no if's or buts! However while that sounds great you will need to pay for an experienced contractor who is used to having someone like me holding thier feet to the fire. Self building is about finding the right compromise.

It's this thing where folk think PH and you need to eliminate every cold bridge.. even columns that are internal.. it looks great on paper but the cost outweighs the benefit.. your door handles are a cold bridge for example. Building houses requires a common sense and practical approach. Yes you do to you achieve a back stop U value. For a column like this that is founded say 450mm below finished floor level then it may achieve the back stop U value anyway with the fire protection and associated air gap. Yes it usually is enough.

Yes.. some of that mesh looks really conjested. I would send some photos to your SE before pouring and make sure they are happy with the layout. You'll need to be right on the ball with the concrete compaction. Scottish BC may ask for photos of the rebar.. if they don't match up with the SE's design you may have a problem! Be safe and get approval for this now from the SE and then you can sleep soundly!

I like this approach.. it's like passive stack ventilation simple and effective. No maintenance. In principle I'm all for PH type houses.. what I'm not in favour of is designing in elements that will require costly maintenance in the future and possible early replacement.. When I see folk doing this I think vanity has taken over from sanity. Off now to support England at the footy.

Are you able to get some work in the building trade even part time at the weekends? This is where you will be able to supplement your academic learning with hands on stuff. If possible get work local to where you want to build.. much of self building is about contacts.. the folk you know, the ones who do a good job and have "flexible methods" of payment. It is possible I think. I'm a firm believer that if you work hard you generate your own luck. Also, at times, you may feel that this is a mountain too high to climb. Do it in small stages.. get to base camp first then plan and prepare for the next part of the ascent. I wish you all the best and keep BH folks updated if you can.

plus 1

Love this solution.. so simple but very accurate!

Good suggestion as a starting point. The justification for the 665mm comes from general guidance for small buildings. Once you move away from the the general guidance these simple (but also conservative) rules no longer apply. Yes agree on looking at wind posts. Your SE may well have gone for the simple option to save you money. What is also important is you maintain overall building stabilty so it does not blow sideways in the wind, or lean over if things are a bit off the vertical plumb. Suggest you go back to your SE and ask them what needs to be done to meet your requirements and the cost implications. A good SE will be able to walk you through the design issues and explain in laymans terms what it is all about. Then you will be in a position to make an informed judgement. Communication is the key!

For me I would weigh up getting a bit of professional advice (say £300 - £400 + vat) against say a days builder's labour and materials that could prove a waste of time.. or make things worse. I hope the following helps a bit. Take an old building like yours 1920's. Door frames tended to be made out of 6" x 2" timber with bricks over. The bricks and timber interacted a little so developed what we today call composite action.. in those days they knew it kind of worked but could not quantify it. Window frames were more sturdy timbers and these too interacted with the surrounding walls. I see this a lot where folk are making open plan spaces and wonder why I want to introduce wind posts and other stuff. But I point out.. hey you now have PVC windows which are very flexible.. some silicon and plastic DPCs which create slip planes.. so now there is no interaction and things start to bend / protest. For me I go back to the way to when the building was constructed.. try and understand what has changed and when.. then try and work out what to do next.. in a cost effective and buildable way. To do this well you need to examine the whole building to get a feel for it and then look in detal at the windows / doors etc.

Hiya. Sorry if I caused a lot loss of sleep, that was not my intention. Indeed, I did not have the full picture as you fed the info in dribs and drabs. For all on BH.. If you have structural concerns then for someone like me to make reasoned comment I need to see where all the loads come from and where they go. If I can't see enough I need to be very cautious.. and this may seem heavy handed at times. @Mulberry View I've copied and pasted some of you text and comment in line. "Is directly from Pasquill's design, which has been agreed with my engineer. The whole of the first floor is in the same principle. Are Pasquill's design engineers not capable of engineering this? " Yes they are. In fact Pasquill's started out just down the road from where I live and I used to work with them on and off. Their lead Engineer was very talented, the owner a talented business person. As I understand they merged with one of the big outfits. If they have the same quality of design team and leadership then they are more than capable. But just to be sure, my SE spec'd 195x47 for the Ledgers for the first-floor joists after examining the scheme before it was signed off. The same principle was used for the roof ledgers, so they are probably overkill. Not looked at that at my end. If I deviate from their designed scheme, will they underwrite it? If you were the engineer here, would you underwrite it if it hadn't been installed as designed? No. But.. in the heat of battle on site sometimes the builder needs to adapt. A good one will often get it right.. often over compensate. Just because there may be a deviation from the design doesn't always mean disaster. The main thing is to spot any deviation early.. check to see if it is ok, if not fix it.. often a belt and braces solution is adopted. Everyone is happy and it all gets signed off. I think you know the answer to that, so for that reason, I have installed it to the absolute letter. So what could I have done differently? Questioned Pasquill? Questioned my SE? I am a ruthless worrier, so I have done both and both times the same verdict was returned. For all. If you have any doubts then ask questions. The easy way is to send photos to the design team and say.. am I doing this correctly? This is the safe and cost efective way of doing things. Fun Fact - My First Floor has been engineered using predominantly top-chord hung Posis and cleared for the 750kg loading needed for a large bath upstairs, along with a 2.3m high 2.6m wide 3-sided triple-glazed Oriel Window. I can't imagine what that will weigh. You can work it out pretty quickly to get a ball park figure. All the best with the project.

@ETC good detail. The vertical strut at the joist end seems to be missing from @Mulberry View? This omission of this dramatically changes the forces in the metal web for example. Best just to seek clarification.

I was bit more diplomatic as I used the word "improvised" @Dave Jones was maybe a bit more forthwrite. @Mulberry View I don't doubt you have done your best and am sure you have not cut corners. However I can tell you as I do this as a day job.. each of the designers may have done a great job.. and you installing it as per the drawings etc. But one of the things I do is to coordinated designs SE wise.. to pick up on the little but important bits that get missed. I often see things like this so don't feel bad. It looks to me that the top flange of your joist is carrying all the shear load on a small bearing area. Think about it.. you have all that floor load and a bit of tying all ending up on the top flange of the joist.. it just looks questionable to me. When I see something like that I always ask.. is this ok? I'm happy to be proved wrong.. I just suck it up.. but if I'm right.. which I am from time to time then it saves a lot of folks bacon. It cost nothing to ask the question, the only cost can be your pride. Please get your design team to review this as if I'm right this is a tiny but major flaw and needs sorted for safety.

I got timed out. don't panic about the joists as by the looks of things it can be easily fixed if need be. But you need to get it checked.

Sorry to say but I think you need to get your metal web joists supports checked not least. I had a quick scant at the photo at the start of your post and it is flagging stuff up at my end as an SE. The ledger piece that has the bolts into .. ICF, I have concerns about that. The method of supporting the metal web joists.. I suspect someone has had a "butcher" at them. I don't say this lightly so please take my observations on board and do something about it. I think you need to get an SE in here as I suspect that your builder may have been "improvising". Next @ETC has been chipping in.. his knowledge of construction details and even more importantly his knowledge of practical construction details seems to me to be exemplary.. my opinion is.. ignore his advice at you peril and have a look at his sugestions seriously. Also appreciate (I do) what ETC is sketching out. It a great demonstration of skill and practical experience, takes many years to perfect and demonstrates how you communicate an idea quickly and effectively.

Thank you for meeting me half way on this, much appreciated.

Ok to go back to the OP. I'll try and expand. Yes I should have clarified... but it should be clear even to you @DevilDamo that this is a bit of an unusual design and can could give ordinary folk on BH working off a budget a false impression. If you know about the regulations then we can cut to the chase? There are a number of cases how this can work. I'm going to keep this basic and generalise. If you want to discuss this more @DevilDamo then I will be happy to engage with you and have a techincal discussion. I would like it if you did engage as it would be healthy / a bit of a learning curve for BH members and for myself as I could get your take on the regs and SE / structural theory that lies behind all of that. Cases are: 1/ If it only carries a roof load.. then we can let the roof collapse provided if does not pull down the other parts of the structure that require a higher level of fire protection. 2/ There are cases when you actually don't need to fire protect beams at all to get your 30 minutes. In fact it is often beneficial to let the light weight part of the structure to burn away quickly leaving the main and heavy parts of the building intact. We take advantage of this approach when designing industrial buildings. What the OP has posted tends to apply in domestic applications.. UC sections can be used that have a low heated perimeter over area ratio thus you can have beams as maybe shown in the OP's post, I suspect they have dropped a bollock on this! I thought I had cut to the chase when Alan pointed out that there was load from above.. and thus we were not talking about a roof load only in terms of the building regs. @DevilDamoAnyway no harm done. But if you want to have a more of a blether about this then please be a devils advocate. At the end of the day I'm happy to share what I know and in doing so I'll probably learn a bit more from you and folk on BH can do so too.

Maybe @Gus Potter Thank you for referencing me. I can chip in but my take on it and the potential solution is long as there are so many aspects to balance... it's late here so maybe for another day. The bit that is hard to do is not actually the cladding spec but how you fire protect the cavity but still allow for ventilation of the cavity.

The starting point here is to actually understand how the structure works. Only then can you come to an informed view. Every design if different. Now it gets technical as while it may not be carrying any vertical load it may be contributing to the stability of another element that requires a higher level of fire protection. Yes this is a slightly different part of the regs.. fire spread. Clearly what @Alan Ambrose has posted is a habitable space.. but not an apartment i.e a bedroom. Agree. Yes some of the stuff you see is complete bollocks and not compliant. My summary for folk on BH.. Use your common sense if starting out on the self building journey. If you want to refine you BC and SE design then great.. we call that value Engineering. But for fire.. be safe folks as there is often no second chance. I'm an SE / Designer and we often design for folk and builders doing daft things, we call this robustness and alternative load paths. This means that if sometihng fails you will see the building protesting.. cracking and groaning so you will get yourself and your family out in time. That is why in the UK we don't read about lots of folk getting hurt due to structural failures. But fire.. look at Grenfell and if you read the local papers you'll see that lots more folk die just in their "wee houses".. many more than Grenfell every year. My advice.. don't cut corners on fire design and safety. For a bit of insight. The fire regs are intended to meet these basic but not all criteria. 1/ They are intended to allow folk to escape from a building. 2/ They are intended not to put the fire fighter's lives at risk.and their families that they support financially. 3/ They are intended to not set light to surrounding buildings and this part of the regs dates back to the fire of London. 4/ They are not intended to allow you to save money and put other folk at risk. This means that if you cock up you may be asked to prove that you were not at fault.. you may have to fight a publically funded body not least to prove you were not at fault ..and could lose your shirt.. everything. My advice folks. If in any doubt play safe and don't cut corners on fire safety.. as if your house does go on fire and if you have taken the piss out the regs (have a mercenary streak) your insurer may not also pay out. There is a bit in the building regs in Scotland that says even if you get regs approval the liability lies with the designer. In summary there is a lot of good comments on BH about this.. but every project is different so please do your research. Good research can save you a lot of money and you can still be safe.. but it takes time and effort. There are no short cuts.

@GeorgeI am signed up to CROSS and an SCROSS so get all the notifications.. surely you don't think I'm not keeping up? No.. George.. I'm not going to tell you any more about your request to "ooh tell us more" but I can tell you this.. you are barking up the wrong tree.. I use my own name on BH.. would you care to expand on your statement and clarify? Some of the software you use may.. I may have had a hand in the engineering development.. I used to spend loads of time writing pops up notes for general SE's (maybe like you) saying.. hey unless you really know your stuff then don't change the default values. I have worked for well known SE Consultancies in the past and know how they can drop the ball. I can give you plenty examples of SE's who have failed and sometimes dangerously. I'm not going to do that in a Public forum. Let's leave it George and stick to having fun sharing what we know on BH and ecouraging young folk.

Hiya all. I totally get your enthusiasm. But you are all spending a lot of time an effort juggling numbers, could be the JH spread sheet could be some nice high end software.. I too have some fancy software in my office but recognise that it's just a tool to give you a heads up. Some folk on BH actually think this will happpen in real life for no extra cost and you will be able to russle up a builder who will play the game.. you are living cloud cuckoo land. The reality is that you need to be able to get a local builder to execute your output and get material off the shelf.. Honestly as a self builder if you get so anal at this stage you have little chance of making your self build a success. I have self built my self and also built houses for othe self builders.. My advice is to use your calculations as a concept model and then adapt to what can be built at a reasonable cost to your specification. A good 50% of the above looks good on paper but is complete bollock in real life. If anyone has a problem with this then you can find my mobile number on my web site or just give me a call on 0771 308 1597.

Thank you for the kind words. I'm an SE and an Architectural deisgner as the day job. @PNAmble that is the kind of SE you need on a self build. SE's know a lot of stuff about other stuff and some of us will chip in to make sure you get looked after. Caution: Not all SE's are like this.. some.. I would never have anywhere near my projects.. I sometimes work as an SE on behalf of Contractors. I have a job on my books and the response from the main SE is bordering on me reporting him to the IStructE for negligance... but the Client will probably do this first. .. not all SE's are angels, some have an attitude problem.