Gus Potter

Not too late to become an investigative journalist!

Etiquette.

That's a nasty number! Ok this seems a bit back to front but bear with me. It's a bit of a long read but hopefully you can pick out some bits that help you. You know what you want to build, how big it is as you have the plans. Do you know how you are going to build it? What are you preferred founds? What's the Architect's / your thoughts - strip founds, raft etc? From what you have we can make a quick approximation of the load the house is going to apply to the ground and how.. raft.. low pressure, strip founds a bit higher etc. Next is to go back to the beginning and find out exactly what the planners are asking for (you need to be reasonably confident you'll get planning in the bag before splashing too much cash) and really look closely at the level of information they actually require. On the plus side here there seems to be pattern for your local area.. the planning computer says no unless we can tick the boxes. You may be able access other reports for the area to see what approach does work and then how you tweak that suit you best. Now we look at what we need to know to build the thing in terms of geotechnical information. We have a mining element, will come to that later. Also potential gas from land fill and associated with that is contamination of the ground water. We would also check for Radon as a matter of course. The gas from the landfill. Risks are.. it forms pockets of gas under your house, explodes and blows your house up, asphxiates you in bed or gives you sick building syndrome (high mortgage rates can have the same effect) .. but the land topography and ground may make that impossible. Just because it is 500m on plan may not mean anything. Just say you have a railway cutting or other topographic barrier between you and the land fill.. how is the gas going to get to your house? If you can identify something like this and make a reasoned arguement then no need for gas monitoring? Gas monitoring is tricky to install and needs "monitoring" = cost thus we want to avoid if at all reasonably justifiable. The ground water contamination carries risk. Just say you have some to make a good story! Clearly we need to keep any contamination away from people and animals but also certain types of contamination will drive the selection of the type, grade of concrete and steel reinforcement cover if we are reinforcing the founds. Things like sulphate content, acidity and mobilty of the ground water can drive the concrete design and this would be associated with contamination at a shallow depth. Also, if you have a public water supply the supply pipework needs to be able to resist contaminated water (comes at a cost), and if you are going for a private water supply... well you really do want to know about contamination. I find the mining fascinating. I've done some jobs where we have bored for mine shafts and shallow workings on small sites where the Client was happy to fork out the cash.. the outcome was that we never found many of them.. but that is not to say they weren't there.. all I learnt was they were not where we drilled! I was convinced they were there at times on some sites but unless you absolutely pepper the place you can't be sure. In the round I often made the argument that on balance of probablity there was not a huge void under the structure, made some assumptions about the type and size of void that could reasonably be there and designed the founds for that. The mining. Now on the above we didn't just turn up on the day with a drilling rig. I carried out a really comprehensive (phase one) desk top study and spent at least a day walking over the site, the surrounding area, looking at the trees, the topography of the ground, and chatting to local folk.. who are often really helpful and sometimes will show you old photos they and their family have kept. Next is re examine the mining records (can be hard) and public available borehole records. I try and find any historic books on the area that maybe relate to industrial activity, old geological records. Sometimes you find nothing at all and sometimes you find a nugget of information that can save you thousands. Now you can imagine that I'm not going to do this for free! but there is good reason for this approach, it makes you think and by doing that you manage risk. All of the above gets coupled up with a typical search (historic maps, floor risk area, general mining risk etc) and info from say Ground Sure or other companies that provide these types of online data services. But the value lies in showing (and just knowing in your own mind) that you have followed the correct procedure in terms of identifying risk, what you do know, what you don't, there is the "what we don't know we don't know".. but life is exciting enough as it is. The objective of this is two fold. It allows me to make a list of all the things that need to be considered, then apportion risk and prioritise each of them. It also lets me plan the intrusive (investgative part) of the site investigation and make best use of the funds available to do that. The funds can vary depending on how much the Client is risk averse.. some Clients just don't listen enough to make their own informed decisions and regret later. To come back to the mining risk. As a quick over view there are a few different types of shallow mines you can encounter. Don't forget that more modern mines had ventilation and escape / ventilation shafts. Early mining acts for example 1862 prohibited single shaft mines. As a quick run down. From early times folk just dug up coal where it outcropped from the ground. Then you had say the Monks that dug bell pits, 12th centuary onwards. Ok a lot of these these have probably collapsed / settled a good bit but there are a few examples localish to me where you can see the depression in the ground from collapsed bell pits.. not for building on at sensible cost. Mind you, I have often wondered if I'll find someone who wants to dig it back out and make a bell pit basement. Jumping ahead you had drift mining.. they dug from ground level and followed the coal seam which is usually sloping. Later these were widened using say timber props, you have the pillar and stall method where they would leave pillars of coal, dig out the coal, chuck the spoil into the redundant bits and when they abandonded the mine they removed the pillars and let the thing fall down as they progresssivly left the mine. Laterally in some places they started using a method called long wall mining. Here they used a big machine to excavate the seam and just let it progressivly collapse behind them. This created a rolling wave of soil movement at the surface which damages houses. But the main thing here is this type of ground collapse happens quite quickly.. a few years, a couple of decades to settle in once the mine is fuly abandoned and the ground water recovers, which lubricates the particulates of soil, encouraging settlement. Older types of mining - some can take 100 years or more before they throw in the towel and cause problems at the surface. All the above relates to shallow mining in general. Deep coal mines tend to have many layers of rock over so the tiny extra bit of weight from a house is negligeable. Now the brief history story is nearly over. Next step is to try and identify where the coal is (if in Cornwall say then there is a lot of mineral mining but the same basic rules apply with a few tweaks), the way the rock and coal seams are sloping (they tend not to be flat and level and early miners followed the seams), how thick they may be.. and where the ground water lies. Now the good thing is that in a lot of the UK there is ground water extraction which tends to lower the water table. Many mines have been shut since the 1980's so the pumping has long ceased. Therefore the ground water level we see now is probably lower than what it was historically, give or take. This can give us the "worst case reasonable depth" of some types of mines. What kind of mining has possibly taken place in the past? If we can find a bit about the ground water average level then we could assume the Monks, earlier methods of pillar and stall were no deeper as they didn't have steam pumps say to get the water out. Many millions of years ago the part of the UK below the Highland boundary fault was well south of the equator before it joined up with the top part of Scotland to make the UK.. our island. There is more to it but for another day. The coal was laid down when the bottom part of the UK was tropical / sub tropical. Later though when we all got glued together the magma in the earth forced it's way up to create what we call magma (granite) intrusions / dykes. This hot material burnt the coal measures and these are often marked as "barren coal". In other words it's of little use. It is a wel known fact that barren coal measures were avoided by the miners. In places dykes can be quite closely spaced and are often identified in the records. Mind you you don't want one under half your house as they are nightmare to ecavate and cause hard spot which is problematic, not just for founds but getting drainage routes established.. Now if your site has say a high water table, some granite dykes then we want to look at that as we may be able to say.. hey this coal is barren / high water table so it probaly has not been mined... thus no need to indulge in expensive driling. Just be aware though. It's not just coal. In many parts of the UK they also mined fire clay and other minerals so we would need to watch out for that. All of the above is the phase one investigation, thinking and research. If you assume you are going to get planning approval in one form or another I would be inclined to plan the site investigation around gathering the information we really need to get the house built. I would try and avoid gas monitoring, drilling if possible (make a big saving) and spend a bit of the savings on maybe more trial pits, some porosity testing, gruond water (especially is you have a basement) to make sure you can get rid of the water easily. On the other hand if it turns out you do have a real mining / contamination issue then we need to know that as soon as possible so we can design for it at the outset and manage cost. It may be worth doing both phase one and two (intrusive investigation/ analysis) at the same time. Then tailor a report with plenty technical detail for the planning submission. Say to the planners, if there is anything you disagree with let us know. At the end of the day if we are going to design the structure to be safe and seviceable then surely that should satisfy the planners? I think the planners want to know that what they are giving concent for is not going to create a legacy problem. In some ways you are just a custodian of the house. Hope this helps a bit, keep us updated and all the best.

Hi there. As a stop gap can you fit an Essex Cylinder Flange - 2.1/4" BSP F Brass to your buffer tank near the bottom? see link below: https://www.stevensonplumbing.co.uk/immersion-heater-mechanical-flange.html Then into that fit and electric immersion say 3.0 kW like below with a timer etc. https://www.screwfix.com/p/tesla-titanium-immersion-heater-14-/74662#product_additional_details_container Mind you that all sounds easy on paper but.. you need to know about the tank and in particular where the coil is located inside. Before cutting a hole in the tank I would phone the manufacturer, explain the problem and find out where they install a factory fitted electric immersion.. which they probably do from time to time. Now with a bit of care you can do this yourself.. if you take your time and use the right tools then you can get them to work.. @Nickfromwales could maybe provide some tips. I take it that the buffer tank is unvented thus it is a "pressure vessel" and as such the unvented cylinder regs apply. Anyway I'll let you mull that over, no need to say any more. If you make a good job of it then at least you'll have a backup next time your system breaks down.. merry Xmas ba humbug etc.. just kidding. On the upside if you later fit pv panels you'll have a ready made destination for the electricity you generate.. have a great xmas and remember that every cloud has potentially a silver lining! If you crack on it could alll be up and running ok ish for Santa.

Thanks Declan, will not repeat error, appreciate the spamming.

Hiya folks. I do like the ICF concept but we are self builders here, not McAlpines ect ( major Contrators) who have Engineers on site checking levels etc. It's self building and we have limited resources. Ok a few options considering what you have to work with. First is ICF.. you have been pouring all day..worrying about bracing and burst out, getting the compaction right and the concete coming on time, it may be raining and windy.. by the time you get to the top of the wall everyone is knackered on site.. the last thing you want to do and are just too tired to do is to finish the top off or start thinking about bedding in fixings. Don't even try to do this at the end of the day. I would keep the top of the concrete 0- 10mm low if you want to "go with the computer"... if you want to be pedantic... not my favoured option. You need to tie the roof to the top of the wall. You can use Simpson L brackets for this which are good for uplift and shear loads. For Posi joists you can introduce a vertical noggings /dwangs if not already provided to give you a nail fixing for the brackets. I would keep the concrete 55 + /- 5 mm low and then later bed and tie down at your leisure a traditional timber wall plate 95 x 45 C16 grade timber on that. You can get it level, fix it down easily and then you can get your expensive posi joists spot on level. I may come over as a philistine but I see this all the time where.. the computer drawing says yes.. but on site at the end of the day, messing about with concrete, with local builders the mood music is.. "NO CHANCE MATE" I know you can go on ICF web sites and the posi joist web sites and it all looks sooo easy on the computer.. but on the ground it is not so. The trick is to identify where things go wrong and actually design and plan for the "shit that happens" Cut yourself some slack.. keep the concrete low and introduce a get out of jail free card for youself by way of a traditional timber wall plate as above. This way you actually get more control over the quality between the two interfaces and design packages as you are able to adjust the wall plate height and at a push it's thickness youself.. you get a fresh start with the roof levels. This can be a bit more work but it it can avoid disputes which are really stressful.. you create a zone where you can just "sort it yourself" and you make a clear break point between the roof and wall work packages if need be. This is unique to the self build thing.. we need to often balance personal stress / family pressure vs the build. I see this and have in the past been a self builder so the above is based on my own experience. You know you have the ability so if you can apply that to make a clean break between the work packages / last lot of contractors it can help a lot. Some Contractors are great and you want to keep wqorking with them.. others it a relief to see the back of them (I'm being polite here)

I think you are approaching this in the wrong way. You are trying to achieve savings buy the division of parts. Lets put this another way.. you can buy a car complete for £Y or the parts and assemble it yourself for £ Y.. but unless you know what you are doing Y will always cost you more than X. Get your SE in now to guide you as to how you marry all this up. I would charge you about £1500 quid to put you on the right track.. sounds a lot but I know I could save you much more and easily cover my fee. I know you may think this is a lot. But a good trademan will cost you £ 1.0 to 1.2k a week, all I need to do is save you a week and a half of labour and I'll have washed my face.. then think about what I could really do for you? I could give you pointers and you can play to your hearts content on your insulation.. we would discuss it all and if I thought you were making an error I would pipe up and say.. hey I think this is wrong .. what about doing it this way..that is good design is all about where we all work together. If you can find a local SE that knows the local contractors. If you have a basement then you are into tricky terratory. You could blow tens of thousands if you make the wrong play.. and that also means if you tell you designers that is what you want.. and if you are too cocky they will just give you what you want as it is your money! I love your space frame concept, @Kelvin has a stunning house with a space frame for example. Your passive house goal.. love that too .. your basement.. that is where it could all go wrong unless you get a handle on the SE design early on. You need an SE for example who is going to stand up to the TF designer, the slab designer and the basement designer on your behalf. What you are doing needs good technical support leaving you to make the fundamental financial and overall design decisions. I know you want to do your own thing.. good for you coming on BH as you'll get loads of free advice from folk that have been there, made mistakes and can tell you.. don't do this! All the best and keep posting.

Hi all. Eveyone get a like here. DRM, I like the simplicity of your model and saw your post popping up a few days ago. I've put a few numbers to everyone's suggestions regarding beam depths as a conservative first guess and made a few conservative assumptions (please forgive the typos / grammer as I'm off duty): 1/ You are probably going to put a lot of glass surrounding the courtyard bit and maybe a fair bit along the outside walls. All this means that we need to control deflections so we don't cause glazing problems and if we control the deflections usually the steels and connections will also be fine when we check that it won't fall down or blow over in the wind. 2/ Slab thickness. Concrete slabs are heavy things. Let's run with your slab thickness of 200mm for now. As others have said there are other solutions that may be more economic, provide more service space etc. In the round we will end up with a similar roof weight or a bit less. Budget on the really simple stupid for now and then we refine. It gives the Architect (maybe you) more room to be creative if they know the "worst case" at the conceptual stage. 3/ I'm also going to treat all your roof slabs as spanning in one direction rather than two. One direction span (not the pop group) means that you could use a structural B reinforcing mesh. Main bars in the span direction are thicker, the transverse bars control cracking of the slab and a few other things. We can make slabs thinner later if we make them span in two directions.. but we need to balance the cost / knock on effects if we do this... there is no free lunch in this self build world. 4/ I'm going to treat all the beams as simple supported and see what the later results are. When a beam is continuous over say a central column this support can attract a lot more load due to the beam continuity and that can impact on what happens at the bottom so you end up putting more load down the internal columns (can be up to as much as 40%) and foundation pads. Let's go simple stupid for now and see what happens. anyway very long beams are a hassle as you may need special transport.. and that often costs a lot..and they are heavy.. Always look at the cost in the round of steels.. too heavy.. too long and the cost to get them on site and handle can out weigh any clever SE savings. Also pick steels that everyone stocks off the shelf. 5/ I'm going to rationalise all the steel sizes so we can later see if we can get the best out of the stock lengths easily available. It also simplifies the connection design.. many other things that will drive the build cost down. Be aware that when you have steel beams with thinner webs and flanges it can really drive up the fabrication cost and these beams are not a stock item. Don't try and be clever at this stage loking for the lightest weight of steel as it will trip you up later. 6/ There are load of other things but let's do some sums. I'll work from the top roof covering down. Remember I'm sizing conceptually based on deflections, not strength design. I'm going to split up the loads into two components / calculations: The first are how much the beams etc will bend by when say it snows or folk are working on the roof and you introduce say pv panels.... call this the imposed or live load. The second is to see just how much the beams will bend by when all the self weight of the structure and the live load is applied. Lets look at some loadings you could have on the roof if you say live in England / Northern Ireland and benign parts of Scotland, Wales. I'm not going to touch on wind loads (that push the building sideways) as that is for another day. For all I'm going to work in kilo Newtons (kN) as units. 1.0 kN ~ 100kg to give you a flavour of what things weigh. Live loads on the roof prescribed by the design codes: Say typical snow load in England 0.45 kN/m^2 ( kilo Newtons per square metre of roof when looking on plan, straight down) Roof access load for maintenance 0.6 kN/m^2, in the design codes. The access load is greater than the snow load so I'm not going to consider snow load any more, particularly as the roof is flat and I'm assuming that there are not any higher buildings nearby that could dump snow on the roof. Pv panels.. say you have panels but want to put them on a frame to get the aspect right for best preformance 0.25 kN/m^2 Total live load = 0.6 + 0.25 = just say 0.75 kN/m^2 Live load ~ 75 kg/ m^2. Incedentally this number correlates to some of the old roof design codes. I use this when assessing old roofs for pv panels.. it's a funny world! Dead loads on the beams: Say a PTFE roof covering with some ply on PIR insulation. But we need to create some kind of slope in the roof to let the water drain. I'll play safe here and allow for a concrete screed to create the fall, say a cement screed or something that averages 50mm thick (say max 5400mm span with a 1:80 fall = 5400 / 80 = ~ 70mm of average screed required once you put the bells/ extras on. Average screed density + insulation + waterproof covering = 22 kN/m ^2 thus 0.07m * 22 = 1.54 kN/m^2 say 1.5 kN/m^2 as a ball park figure. Take the concrete slab as 200mm thick as per the sketch up model. The weight of this is the density of a lightly reinforced concrete (I'm avoiding a thin slab with lots of expensive/ complex rebar)* the thickness = 24 kN/m^3 * 0.2m thick = 4.8 kN/m^2. Note: I have not spent much time mucking about with the other loads as the concrete weight really is the dominant component. Now we need to put in a ceiling and some services on the underside. Allow say 25 kg/ m^2 ~ 0.25 kN/m^2 Add up the total loads: 1.5 + 4.8 + 0.25 = 6.55 kN/m^2 say 6.6 kN/m^2 ~ about 650 kg/m^2.. Now that is quite a lot if you compare that to say a timber flat roof with say posi joists which will clock in at a lot less.. but I have a light weight warm roof on part of my house and you can hear the birds trotting about.. and I'm pretty deaf to boot! Ok now we have some loads on the roof split into two components.. the live load and the dead. I'm going to take your longest spanning beam as 5460mm and that it has to support a roof slab width of 6445mm. First calculate the uniformly distributed load on the longest spanning beam. Live load only = 0.75 kN/m^2 * 6.445m /2 = 2.42 kN/m = w1 Total load on beam = 6.6 * 6.445 /2 = 21.27 kN/m =w2 Now let's calcultate the amount of deflection we can expect: Using the formula (assuming all the load is uniformly distributed along the beam) Deflection = 5*w*L^4 / 384 E *I. Lets try a universal UK beam section of 305 (deep) x 165 (flange width) UB 46 kg/m which is a good mid range section, off the shelf and can head off problems (Architectural input) when you come to connection design and the beam twisting / buckling.. for another day. w = the load L = the length of the beam E = is what we call the Young's modulus, the elasticity of the steel I = the second moment of area = a geometric property of the beam For the live load the anticipated deflection mid span will be about 5* 2.42 * 6445^4 / / 384 * 205000 * 9900 * 10^4 = 2.67mm that is not a lot but! For the total load the overall deflection mid span will be about 5* 21.27 * 6445^4 / / 384 * 205000 * 9900 * 10^4 = 23.5mm The 23.5 mm deflection is the key! That is quite a lot for the longest spanning beam to bend, nearly an inch in old money! But here we get a bit more thoughtfull. I know that once we start to stiffen things up and get them all interacting I can reduce the overall defection a good bit. I think I could get this down to under 15mm once I start to value Engineer. The main thing for me is the glazing and how you handle the deflections.. and all that feeds back into the Architectural side.. the detailing, thermal bridging etc.. it gets reallty interesting here. Lets go back to what @George and @saveasteading were advising! Span / 18 and span / 24 @GeorgeMaximum beam span / 24 = 6554 / 24 = 273mm beam depth @saveasteading Maximum beam span / 18 = 6554 / 18 = 364mm beam depth You can see I have picked a UK beam with a slightly wider flange which is smack bang in the middle. In summary George and SaveaSteading are two highly experienced Engineers.. it should come as no surprise that they know their stuff.. all I have done is put some numbers to their experience and picked a beam with a wider flange! My span to depth ratio is 6554/ 305 = 21.4! I'm not shitting you all, I've not manipulated the figures.. I just thought I'll write write this post, do some calcs and if at the end I disagree with the other posters I'll say so and why.. but no need at my end to disagree. @DRM ask this.. now you have comment from three Engineers, an Architect @ETC, professional Contractors, self builders that have been thee and worn the tee shirt and more... time for you to make a donation to BH even if it's a tenner.. it will be good for your sole.

Hello there ash. Happy to have a quick chat with you on the phone if only to reassure. You can pm me or give me a Pm for my number, you'll find me on the internet also. I'm based near Glasgow. I hope so! Agree. It's ok to have a quick chat to understand the background but not ok to judge others / criticise their design without letting them know you have been asked to formally review under instruction from the Client. It's not professional and also basically unfair. It's not a big thing.. my designs get reviewed / checked all the time usually by an in house Council Engineer (or they contract out for checking SE services) on domestic projects, on say bigger industrial stuff ( I often work for the Contractor) by the Clients own Consulting SE. It could well be that the Architect, maybe you, did not fullly communicate to the SE what structural envelope was available to them to fit "their stuff into" and they did their best to fix it at a reasonable build cost vs intrusion into the Architectural space? It may be that the Architect did their best to achieve compliance with the building regs and maybe just did not know about these "structural bits" as they are not SE's?

Yes it can at times, explanation follows. No point in having a fabricated stair if the connections are not considered. Hello all. A quick bit about glass ballustrades, off the shelf steel ones and stair cases. These types of barriers / stairs are designed to resist the prescribed loads in BS 6399 part one and BS 6180 for example. These codes allow for a horizontal load to the top of the hand rail and the infill bit below, could be glass or spindals. There is also a limit on the amount the handrail at the top can deflect horizontally.. serviceability.. so it doesn't "feel insecure". Now in particular the glass balustrade manufacture's need to be competetive so they test (and make public their results) their product on a very stiff and strong test rig that doesn't bend much (twist) at all. This way they get the best performance out of their product, fair enough to them, it's a commercial world. When they use a stiff test rig the distance between the bolt centre and the centre of the effective bearing ( the bit at the track edge) is at it's maximum thus the bolt tension is at it's minimum. If you're fixing your balustrade track to say a well prepared thick concrete slab then this could come close to the stiffness of the test rig. But if fixing to something else, say timber or there is roofing membrane between the track and underlying material then this changes (increases) the forces in the bolt and at the track edge, quite a lot at times as it shortens the effective distance between the bearing surface at the edge of the track and the bolt. What the calculations I posted do is to basically take the horizontal loadings on the balustrade and multiply them by the height at which they act. This gives the bending moment, a rotational force in this case, just like a wheel nut spanner. This rotational force is then worked back the other way to give the tensile force in the bolt. But the tensile force will be different, and the difference can be quite a lot, depending on what you are fixing to. The tensile force in the bolt has to be counteracted by the edge forces on the track. Because the distance between the edge of the track and bolt is small the horizontal forces on the balustrade fixings are very much amplified. If you are fixing into timber or something that is softer than the test bed the timber / something can easily crush near the edge of the track, so you need more timber say which shortens the effective distance between the bolt and counteracting force at the edge of the track. The forces in the bolt are now much more so you need to check the bolt and what you are fixing into to avoid crushing of what you are fixing to at the edge of the track. The calculations are repeated (iterative) until you find the balancing point where the tension force in the bolt is equal to the material pushing back the other way at the track edge. @Alan Ambrose Good spot the shear loading. As this is a side fixed track the vertical shear load comes from the self weight of the balustrade thus I check the bolt for combined tension and shear. This is particularly important if using resin anchors. Now the above may sound like a maths excercise but actually it can avoid disappointment. One example. You fix a typical slender aluminium balustrade track to the timber edge beam of say a stair or balcony. You have a party and a few folk lean against it. In the morning you go out to clean up and find the balustrade feels a bit loose. All it takes is for the timber to crush a little at the very edge of the track and now it feels slack. If you can't access the bolts to give them a tighten up then you often just have to live with it. Best to design it right in the first place. In fairness to the manufacture's they don't know what you are fixing to, the designer of the main structure often does not know what kind of track / balustrade you'll go for at the end of the day so there is this design gap, no man's land where one key part is often not explicitly checked and often overlooked. In Scotland we insist that all parts are checked to ensure everything is safe and serviceable, hence the calculations posted. This also includes fabricate strairs to ensure the loads on the stair are transferred safely to the main structure.

Jeremy did a great spreadsheet, but it it a preliminary assessment tool. Basements are a different animal. Take a basement that is cut and filled into sandy soil, drained all round the outside, a type C drained protection, the mobile ground water is kept clear of the insulated walls. You can maybe with a bit of caution / pragmatism treat the walls as part of the floor slab.. there is "but" later. But if you have ground water swilling around the outside of your walls it will tend to cool them much more. The form factor is only applicable to ground bearing floor slabs, could be your basement slab.. but not the walls. I may have an old version of Jeremy's sheet? On ground bearing floor slabs an input value is the exposed perimeter (P) vs the area of the slab (A)... P/A ratio. Basically the larger the slab the less exposed edge area, the P/A ratio drops which means it performs better... that is why on big industrial buildings sometimes in the past we only put insulation round the edges and down sides. If you are doing preliminary pricing / conceptual calcs I would add 25 -30% to the insulation in the basement walls until you know much more about the ground (type of soil) and ground water flow. Here is a good link that give some U - values of typical soils. When doing detailed calcs these need to be converted back into thermal resistance, an R value. But these values don't account for mobile ground water. https://polyfoamxps.co.uk/what-u-value-is-required-from-a-ground-floor-construction/ Once you get a handle on these bits an bobs you can then decide how much heating you want to install in a basement. How big is the lobby, if just a few m sq then probably none but if larger who wants to come out a room and be hit with icy air. In some ways if it's an entrance to your house I would want some flexibility here to heat it plenty at times.. when your visitors come in from the cold they want a bit of .. hey it's nice and warm here while they take off their coats and hats. First impressions matter.

Hi Paul. Post a photo of typical wall if you can. Appreciate you are not concerned about damp problems. Pity that as it is probably a cement based render, can easily trap water. Ok going back to basics. For bricks to suffer frost damage they need to take in water which then freezes. My first real job after leaving college some 40 years ago was in a materials testing lab and one of my jobs was to take the bricks out the freezer in the morning and put them back in at night. Now for frost damage to occur you need sufficient mobile water for the ice crystals to grow big enough to spall the bricks. Your comment about Poland / Scandinavia is interesting, add say parts of the USA and Canada to that list. I think there are a few reasons why their render stays on fine. One is that although it gets much colder the climate is different, they typically don't have the gulf steam blowing warm moist air for a few days and soaking everything followed by a rapid change in wind direction, for us in the UK that biting and chilling north east wind rapidly cools and freezes things quickly with rapid expansion. If the weather progressivly get colder then the external humidity tends to drop (Poland?) which drys the walls (even though it is cold) so less growth potential of the ice crystals. Also as they know it gets very cold their tradesfolk understand the problem more. You'll have read about saying using SBR bond for render, but there are few trades folk that actually read and follow the instructions which are really important.. you need to let it get tacky so it bonds to the render which it does really well if done right. Let it (SBR) dry and you may have better luck getting render to stick to glass... but funnily a lot of folk on BH will have found hard spashed render hard to get off their new windows.. some adhesion.. wrong place, but nowhere the levels of adhesion and mechanical key you need to keep render in place for a long time. You're right in that if you insulate on the inside you tend to shift the dew point inwards. Also I can follow your thinking about causing a problem higher up the wall. It's rare that you see brick spalling high up in a wall due to frost damage as I think there is enough hot air / heat at the higher level to mitigate. If it was my own house I would say. I'll first test by approximate calculation what happens if I turn this into a timber frame with 230mm old external masonry rendered leaf analysis. Ok you have thicker masonry on the outside but the principle is the same. Here we want the dew point to more often than not to (it shifts depending on season and internal / external conditions and can at times reverse) sit in the cavity, we then let any condensation drain down the cavity or evaporate later when conditions change. Ideally we want to avoid hitting the dew point. But that often means creating more drafts / ventilation in the right place. You may need to sacrafice any meaningful insulation effect you get from the masonry, which won't be a lot anyway. What would happen if I strapped and lined the walls, insulated all that with plenty air tape to stop the water gas getting to the problem area in the first place. Can I detail that at the bottom so water can drain into a solum space without rotting the ground floor joist ends (which you have recognised) and maybe get some cavity venting at the top of the ground floor walls. We are not talking a massive draft here, just enough to capture any water gas that gets past the air tape and stop the cavity from becoming musty. Ideally you want to remove the water gas (reduce air relative humidity) before it condenses. In principle this works until you come to detail it so it actually works, the tricky bit will be at the bottom. EWI shifts the dew point outwards, but it can look awful if not done correctly, not always work properly, particular when you come to sort out all the details and spoil the character of the house. I would explore all other options before going for EWI. This all sounds a bit dramatic and technical. The most important thing is to stop the walls from getting wetted from the outside as much as possible; by checking gutters, pointing and ground levels and splash zones from say slabbing etc. Then making sure you get plenty draft round the house and (sun on the walls in the winter) if you can to dry them back out. The damage in the UK is often done by a North East wind, I would focus on any elevations facing that way first. If you have big overhanging trees and / or shrubs against the walls then you are starting a fight with one hand tied behind your back. Keep us posted.., a photo or two would help generate more targeted comments. There are a lot of folk on BH that know a lot about this, more than I so a bit more visual info could encourage them to chip in with their ideas. Some are experts at insulation / thermal modelling so could maybe put more flesh on the bones of what I'm suggesting.

Is it old steel say in an old barn or new steel? In your last photo I think I can see some roughness on the outside edges of the bottom flange suggesting it is old steel. If so you'll need to take that back to the bare metal. Do it now as later it will be messy job and spoil your curtains for example. Rust dust is a bugger as it stains many things it lands on. If new steel then the SA2.5 blasting should have removed the mill scale.

Thanks ETC for the advice. I'll see where I can apply that method more often, has given me food for thought so thanks again.

Hello Paul. This is a good source of information and discussion. https://www.heritage-house.org/damp-and-condensation/managing-damp-in-old-buildings.html Pete Ward has upset a lot of folk in the damp proofing industry so you can have a bit of fun reading around seeing what they are all saying. Main thing is if you spend a bit of time now you can inform yourself much more.. each house is different. When faced with this type of issue I always look at what is happening outside. For example, the roof details (eaves overhang and guttering) which way the building faces, the pevailing wind (the east, north and north north west walls get the coldest freezing winds that cool walls a lot and quickly which is important as they freeze before they can dry out a bit), overshaddowing trees, ground levels, any potential DPC.. be that slate or a less permeabile brick, say a good quality clay brick or an engineering brick and so on. I next look at the condition of the building; the gutters, the pointing, mastic around windows, weathering details and so on. I also look for signs of movement, normal cracking associated with an old building and for more significant structural cracking and lateral movement of the walls. All the time I'm thinking.. what can I see but try and avoid drawing any conclusion at this stage. Lateral movement bulging of the walls is really important as you need to be careful later not to make the problem worse by say lowering or draining ground (to solve damp issues) and causing shrinkage of particularly clay soil under the found. I try and identify where moisture can be penetrating from the outside. Next is to go inside and look at the construction, if suspended floor what kind of solum, non or just earth or ash / blaze say with a bitumen layer. If stone flags what are they sitting on. Stone flags can be quite impermeable but can sometimes feel damp on top due to condensation. I then move onto the condition of the structure. Are the structural members sound, are the signs of infestation or dry / wet rot. If so how is this happening? what conditions prevail that are promoting this behavoir?.. damp / warm and lack of ventilation.. a combination of the three particularly invite unwelcome guests (mice etc)and organic growths rot and moulds for example. In summary I would do a bit more research before adopting any particular strategy. I can't make any more constructive comment at the moment until I know more. Photos would be helpful if you feel able to post. Once you gain a deeper understanding of how the house behaves then you can plan a cost effective insulation strategy and get to the bottom of your concerns about freeze thaw of the bricks. Remember that most common construction materials contain mosture to some degree. Often if not totally saturated and if a continuous flow of water is not present then ice crystal growth is limited.. I have this discussion from time to time about the NHBC / BC min found depth of 450mm.. if there is no water supply to grow big ice crystals how is the found going to heave significantly? Look forward to hearing more about what you are doing.

Best thing to do would be to post some drawings and a few photos of the inside and external elevations. I do a few loft conversions in the day job but your info is so limited I can't make any resonable / helpful comment unfortunately.

Ouch! Here is a suggestion, from someone with a Contracting backgound. Get a load of ballast and a few bags of cenment delivered to site. I take it you have a machine with a bucket on site and a bag mixer knocking about, not a mini Belle.. a proper mixer. Batch up the lean mix for the cavity and take that to where you need it with your idle machine and pour it into the cavity, all you need to do is tamp it in carefully so you don't burst the walls. No need for a barrow. Any left over ballast you'll use it elsewhere for bottoming, slabbing etc. Lean mixing cavities is a great way of teaching apprentices as it is low risk. Say you need a small batch as you always do on site. Are you going to get a spot mix in for half a cube, the delay and time it will take you to organise that? If you take a bit of time to teach your employees (especialy apprentices) and get them to recognise that they need to be working all day for a fair days pay, but that you are not thrashing them to death then this make good buisiness sense. There is a time for heavy machinery and a time for thought and finesse. You future looks bleak as a Contractor. I'm sure you are making hay at the moment but the good times will come to an end.. they always do.

Agree. Your right Joe.. not a good idea squeezing stuff together like that. Good spot both.

I'm a Scot..but British if you catch my drift. I say sod them.. what about some York stone or Honister Slate from the Wales for example? What about Bath limestone if you want something a bit more special?

Self building means you need to build a relasionship with the folk you are working with on site. I know you are trying to get a price for everything but that is not the best way. Six cube of concrete equates to a 15 tonne load of concrete ballast and a few bags of cement. Talk to your guys on site as this is the kind of job that can be done when the labourers have not much else to do. Bung a bit of cash their way and it will work out fine. If you know what you are doing then hand mixing six cube of leanmix over a couple of day is not that hard.. I have done it many times over the years. I think a lot of folk have gone far too soft.. it is less onerous than picking Asparagus in Linconshire and you don't smell so bad in the toilet after.

I would like to see much more of that elevation and what is on top before making further comment. Also I'm wondering if anything we are supposed to be looking at is part of the horizontal bracing system.. @regrets if you want best input input then I think you need to post a lot more photos.. if not you need to call an SE.. for this a basic rate is £85.00 per hour can be expected. You may need to take a gamble.. if the supplier is wrong you may be able to get some / all of that fee back..

I don't know as I can't see enough of the structural frame, what it is holding up and the load path from the roof down to the supporting structure. What is the span of roof you are supporting? Where in the country do you live.. London or Aberdeen.. snow loading is important. You see some behaviour that exhibits some twisting.. which is indeed torsion in broad terms... it's ok to say what you see! I think.. what is going on round about as you have timber, metal and connction bolts etc. To give a more detailed answer I would need to see more panoramic photos so I can take a view on the loads. Next I would need to see the section profiles (thickness, shape, material and grade) so I can assess what loads are going where. I would like to see if the metal profiles themselves are out of shape under load. Once I know a bit more of about that then you can start to put together the basics. It may be that the timbers you see are just there to make it easy to fix plasterboard to! In other words it may all be absolutely fine but the timber is not inherantly structural has twisted and shrunk. It may just be good design.. let's chuck in some wood as it's easier to screw / nail into! I do this all the time. I bolt timber to steel (steel comes with the holes in it, I try and make it idiot proof to some extent) so the folk fixing the plaster board etc have something easy to fix to. Or if the metal profiles are out of shape it becomes a different animal. You see some twisting. As an SE I would want to know.. is this due to lateral torsional buckling, local buckling or distortional bucking and couple that with the grade of aluminium or is it/ and a manufacturing defect. Now I have laid that on thick but to learn about this takes a Masters degree as a minimum in Structural Engineering plus further study.. so it's not bedtime reading. To be blunt few suppliers of these sections really understand what they are really doing and how their profiles interact with the rest of the structure. It's a specialist subject in the SE world as not least these are what we call thin walled sections. Post more panoramic photos and you may find you don't have a problem at all

It is possible but there is a catch. There is to my mind a massive and fundamental niavity in the west where we think that the rest of the world thinks like us. They don't. Ball park figure 2/3 of the world are either driven by autocratic regimes or a form of religion that is fundamentaly not compatible with our western way of life. The last thing on my their minds is the environment and the sooner we wake up to that more chance we will have of saving the world climate wise.. and all the organisms that rely on our fragile ecosystem. I grew up in Arfica, spent lots of time exploring that continent, understanding different cultures. I have also travelled in the middle east.. I remember when I was a kid turning up in Beruit round about 1976... someone thought it would be a good idea to shoot up the airport terminal and chuck in some hand grenades.. there was dead folk lying about, blood all over the floor and up the walls.. nothing has changed.. except now the weaponry available has become much more devastating. I had the pleasure of briefly meating Idi Amin, he was just a corporal then but became a president. The western world has become beholdened to regimes and religions that are not compatible with our way of western life. We in the west think that by appeasing they will be nice to us.. they won't. In the West we have allowed these countries that don't share out way of life, values of equality and freedom of expression to become our manufacturing base and dominate the supply our some of our base materials we need to manufacture, there will be a price to pay for this... I think we in the west will be invoiced sooner rather than later. I say this as an Engineer.. it's partly logic and partly probability. Until we address the balance politically there is little chance of us saving the plant. The other 2/3 of the world and in particular their leaders will just do enough to make sure that they and their immediate cotary will come out not too bad.. and sod the rest of humanity... and that means pretty much all of us on BH! Sadly it may need a war that significantly reduces the human polulation and that may ultimately save the planet and all the other organisms and animals that share our land, sea and atmosphere. To finish on a high note..yesterday I was chatting to a fisherman pal of mine. He was showing me some of the fish he had caught and released off the the west coast of Scotland. He had caught a 200lb Scate, photographed it and released. The animal was beautiful, enormous, it's colours were so vibrant.. it made me wonder.. why not just leave it alone? he said it was a common scate and these are protected so catch and release.

Ok no money tree. What about taking this approach? If you have piles and a ring beam then the concrete is probably going to be around a RC35 (the RC indicates that this is a reinforced concrete) and thus if you lay, compact and cure it properly it will be pretty resistant to moisture. Now we do this a lot on industrial buildings.. B & Q for example. Take a leap of faith and recognise that this is not a habitable space.. all you are doing is controlling moisture from the ground in most circumstances. This type of conrete is good enough to be pretty impervious.. but as it is a stronger concrete it will tend to crack. so we put in reinforcement to control the crack width. In other words treat this as an industrial building and there are tens of thousands of these that are built this way. BC are ok with this appoarch. Just remember if you want to convert it later to a home office it may need a lot of extra work, not least as you have an unisulated slab. If I was designing this at concept stage this I would decouple the design into different elements. It will save you money on builder cost. I say concept as there are doors / threshholds etc that need to be considered and you may have varying ground levels externally. I would pile it first. Now you have potential ground heave, hence the clayboard. I would put the clayboard under the ring beam so you don't generate uplift in the piles. I may want to put it up the sides of the ring beam as well to stop swelling soil pushing the piles sideways. Once your ring beam is in place build your brickwork inner skin. Lay the clayboards in the middle and put the DPM on top of them. Then do your reinforcement for the slab and cast the slab. Now that sounds simple but there there are things you need to know about clay boards.. some need watered so they degrade and collapse. To get more guidance tell us about what the size of the garage is (floor span and length is important, as it relates to a good economic slab depth vs the amount of rebar you need to use and if you need joints in the slab) and why you need clay boards in the first place.. a soil report would be helpfull. Some garages are small and don't need much thought.. but some are very big.. the size of a small house so you can lose a lot of cash if you don't grasp the basics of design. I think you need to go back and identify how the soils behaves, what the piles are doing, if you have trees close and thier type and size and your ground levels. Only then can you get the right position of the DPM and DPC's. Best thing would be to post as much info you have as this will invite the best response from BH folk.

Fair enough.. but it's primarily the fittings, bends couplings etc and the glue if you are using it. The main thing in my view is that if you are using above ground fittings and brown pipe that you may sure the seals / glue are compatible. What's the latest code we should be using? .. and what parts of that have been ammended relate to what we are talking about?