Gus Potter

I hope not! Of course.. voluntary work is so good for the soul. Ok the maths. I'll relate this to wind load on a house then cut to the chase about driving at hwich I'm a bit not Nigel Masell.. more like Rowan Atchinson.. enough knowledge to be dangerous but without the cash to excecute well. Excuse the spelling and grammer please. Simplistically the wind load on a house is related to the speed of the wind as we know for life experience. The general equation is air mass x the wind speed squared. For interest ( if you have nothing beter to do) I've screen shotted a wind diagram from the BS design code. . For the non mathematical often we can simplify maths by removing things that stay the same.. say the weight of your car. This lets us quickly compare like with like even though the number we get at the end does not equate to say a true real life value that we could then use to design a roof truss say. We can call this a qualitative analysis. In Oxford the basic wind speed is 20 metres per second... about 45 miles per hour (gust speed).. Build Hubbers.. do not use this as a value for your design.. as it then gets modified a lot. In the North of the country it is say 27 - 31 metres per second. Using the equation.. force = mass x velocity squared the two results can be compared in a qualitative manner. That said I hope the wind diagram helps you see how things could change for your house design depending on where you live. If you have big areas of glass then its a consideration.. is the glass and double glazing going to be ok if I live in Cornwall say. The mass of air is the same (except in the far north and the Hebrides where it is rarified by Whisky fumes so is a little lighter) so the "Energy ~ = mass of air * wind velocity squared. Just say the mass of air is 1.0 something units 1.0 * 20^2 = 1.0 * 20 *20 = 400 units. In the North it's 1.0 * 27^2 = 1.0 * 27 *27 = 729 units.. nearly double the force! When explaining to other designers about wind behavoir I often use the car velocity / breaking distances model as an example as most folk can relate to it. If you hit a kid when driving at 20 mph the energy you hit them with is similar to the wind. Your car = say 0.75 - 2 tonnes.. but it's the velocity that causes a lot of damage. Say your car weights 1.0 unit of measure. At 20 mph the qualitative units are mass of your car 1.0 * 20 * 20 = 400 units. At 30 mph it mass 1.0 * 30 * 30 = 900 units. In other words that extra 10 mph matters a lot. The extra 10 mph has more than double the energy. Now it's known that the survival rate for humans rapidly decreases when the intensity of the energy delivery increases if you get hit by something. This is what we call accelerating or braking if you are in the car. When folk go to the moon they get accelerated by a rocket but slowly. Now the driving courses are intended to make sure you stop before you hit anything.. as a kid could then get slowly rolled over by the wheels of you car at 1 -2 mph. The main thing about the above it to recognise that with a small increase in speed you need to exponentially decrease the rate of acceleration. To be frank.. if you hit someone at a couple of miles an hour you are unlikey to cause them organ damage. But as above the collateral damage comes from then running them over with your car or causing them to fall over and then damage their head say from the fall. Now if you are in an airplane.. the guy / doll up front has a big interest in not crashing at any time! At 150 - 300 knots a bit of difference in relative ground speed is not going to make any difference to you not getting squished. The last thing they are wanting to do is to make contact with anything solid or semi solid in the air.

Well done both. There is as expected a wide spread of comments on BH. Grand Designs enthuses people to think and encourages. Do you know what it actually cost you? The builders would chew your hand off to get their sign up on the scaffolding. Did you do any cash deals with the builders or discounts that normal self builders can't access etc? I know you have to say no or you'll have the tax man chasing you! What other business relationships exist.. see you are on insta for example. It would be great to hear you are a Nurse say and hubby works for the council cleansing department as it would really show the C4 audience what can be achieved if you are just an ordinary run of the mill type. Have you or are you making a donation to BH?

It's a dilemma! Over the years I've done a few UF systems and each time I learn something new, improve where I can and adapt the design the based on my learning and what new on the market. The house we have at the moment is a 1955 house with suspended floors. We took the back off it and extended out to form an open plan space. The extension is a concrete slab on PIR on grade. But the floor levels in the existing house vary and as they are now forming part of the open plan space we have a mix of materials forming the floor. Timber / concrete and a level variation.. it's small but it is there. Also the existing house solum is sealed with tar and a bit compromised in places thus we have different moisture levels. All of the above results in movement between winter and summer which is noticeable.. if you are inclined that way to have these thoughts. For this house I floated the engineered flooring on a 2.0mm thick layer of foam, just the bog standard stuff. If you jump about on the floor you are aware that the different parts feel more solid than others. But again I'm always "monitoring! most folk wonder if I'm ill when I mention. Now fair enough the foam insulates and makes the UF less quick to respond. In the odd spot where the floor levels were a bit off locally I added some extra strips of foam as a packer. But we have lots of rugs and so on which do insulate the floor much more so than a thin layer of foam. If you lift a rug the floor is much hotter under. We have a bathroom on a supsended joisted floor. The tiles are these large format ones. The UF pipes are in a screed on PIR between the old house joists, no spreader plates. A while ago I posted about this and @nod as always provided some great advice. I followed it and sure enough after almost two heating seasonal cycles no cracks in the tiles. Thanks @nod! The main thing was the use of a decoupling matt. When I first started messing about with UF these products were not available.. mind you neither were large format tiles available to the DIY market at an affordable price. Now when you read the fine print of the flooring suppliers you nearly always breach their T & C's in terms of what you need to comply with. One it the temperature range. Where you have UF pipe conjestion the floor can get quite hot at times cf other areas. I just accepted that is was nearly impossible to comply for our house so took a pragmatic risk based approach. In summary I did think about glue the floor down. But then I though what happens if I get a leak in the kitchen sink say . Lifting any damage glued down flooring could be a nightmare! We have had a plant pot that leaked water and did not spot. Some minor damage has occurred but I know I can easily fix the floor if need be.

Have fun. Good design is very much an iterative process... so many things you can do. Sometimes it's easier to say.. we don't want that and that can help narrow down the field a bit. Alway sleep on stuff and let you mind work away over night. I've still go bits to finish off in our own kitchen.. just waiting for the time to do it. One think though. The sink is under mounted and not expected to last as long as the worktops..I hope! The worktop is Silestone and the cost of that makes you less inclined to change it. All the worktop fitters said you need you sink in place and we will stick it to the top of the sink with our super strong resin / glue. mmm.. how do I then replace the sink if we crack it say and not risk damaging the worktop? What I did was to say.. fit the worktop with no sink. I then build a timber cradle, took it to bits again, lifted the sink up from below and siliconed it into place.. then reassembled the cradle. Now if we want to relace the sink all we need to so it to cut the silicon bead and drop the cradle... well that is the theory!

Yes type one is aimed at good compaction and achieving density. Add a little cement content and you have a lean mix that forms a lot of the sub base of our motorways. I think Geocell is much more like a single size aggregate.. like railway ballast. Now as an SE I should be using some technical terms.. but my best answer is that for Geocell which is pretty much a single size material it just needs "shoogled" into place. Thrashing it to death with say a 10 tonne vibrating roller will just damage it. I've specified this stuff and the results (feed back) so far are good for the loads I want it to carry. Goecell is not new in terms of material composition. It's stable, not frost succeptiable for example. It is bulky and a bit of a shit to shovel apparently. The top of it is a bit rough so maybe needs a bit of blinding. I'll leave the last bit out as this is my IP property. Now @Alan Ambrose for example. The NHBC put a limit on hardcore fill for rafts foundations at 600mm.. and this would apply to say EPS and XPS material on hard core. I wonder if Goecell have ideas o how thick thierstuff can be? Their stuff is not heave prone, not frost prone and has insultating properties. This has got me thinking.. can we do rafts with lots of Geocell and little if no EPS or EPS where we need to go deep to avoid clay and tree root heave for example. Now Geocel is light weigth so on bad ground we dig out some crap stuff and replace with a lighter structural fill.. now we further reduce the soil loadings. I'm just chewing the fat here folks but BH is at the cutting edge of things.

Slating is an art and traditional craft. It gob smacks me how often folk claim to be slaters but don't realise how slates in valleys and at roof verges need to be tailed. It not just for appearance it has real meaning to prevent dripping and compromising the lead in the valley and the verge. When cutting a valley slate you pop it upside down and cut the tail the other way up so the regular rain water does not drip on the the valley lead.. is uses the miniscuse principle and trickes down to the bottom of the valley where the thick lead is. These are traditional skills. it also protects the sharp edge of the slate forom frost and maitenance damage. The natural bedding plane of a slate is not suited to getting cut by a diamond saw! At the roof verge we do the same so the water is shed back into the roof rather than rotting the verge. These things are the basics of slating that were drummed into me and apprenticies. Folk think.. hey I've got a slate roof and it will last longer than concrete tiles.. well it won't unless you know these things! Whoever slated this valley is not slater and you would not get anywhere near my house!

I love the amount of work you have put into this as a concept. This is improtant as you have sat down and identified the type of house that would suit you and the internal spaces. For me Perthshire is stunning. Some of my family lived in Perthshire the rest now on the inner hebrides.. the white beach is the end of their garden there is no fence just the sea. The critical thing is the services and that is going to have a big effect on the overall build cost. Once you start to live in rural Scotland there are other costs.. travel.. just to get a pint of milk.. don't underestimate these. Take your car for a service.. you may not get it back for a week! But the land prices in Perthshire have rocketed but olocal services are still expensive. What is still affordable is Argyll for the self builder on a budget.

Hiya. There is a lot of well meaning advice here in the posts above. I do this as a day job and you are inviting trouble. I see this all this time and folk end up in a nightmare! There are maybe one or two SE's on BH who know about this stuff.. the rest are.. it's not their day job. I can't see all of the roof truss layout but I'll hazard a guess that some of your intermediate walls are non load bearing. Now it looks like you have ground floor extension with a beam over.. if you change the loading pattern you could over load that beam for example that allows access to the extended part. You are playing with fire here. Just say you come to sell the house and a surveyour sees you have made alterations to the attic. You won't be able to sell the house... even if you think your alterations are sound. You'll need an SE to sign it off. Please do this right and pay an SE for advice. Aye but this is let's say putting a bit of a gloss on things more often than not! If loft zone want to get in touch with me them I'm all ears! I would love it if they have a good economic load bearing and compliant solution as I could sell this day in and day out and sign off on it too! I keep pulling these folk up about the shite they are selling for say fink truss aplications. Some of them approach me to sign off their designs. OP and there are a few of these loft boarding folk proposing insultating with spray foam insulation so we need to have a look at the dew points so your roof does not end up rotting away! Now your basic distributed design load on a modern lightweight roof truss is 25 kg/ square metre applied to the ceiling chord. There are other loads but for now. Add 11 kg/ m^2 for your flooring leaves you with 25 -11 = 14 kg tops depending on the truss spacing.. Most of then are selling on the basis of 25kg.! Now take the insulation wieght off this. Then go back to the truss manufacture and ask.. can we insulate out our loft and floor a bit of it.. if so how much load can we put on the new floored bit! Now some of these loft folk are saying.. we can give you a bigger hatch.. now you are cutting a structural truss. Just look at the sizes of the bit of wood! Even as a lay person you must be able to see they are slim and slender. Now just say you are going on holiday to Spain and the window in the airplane is a bit small. I pitch up and say.. no problem pal.. I've brought my Dewalt and I'll just cut this tiny wee rib out as it is so small it can't be doing much, fit a new window bigger from B & Q and you be good to go!

Hiya. Happy to give you advice where I reasonably can. But I need to see all the drawings, a panoramic set of photos of the house, any adjacent houses and all your drawings and ans SE calcs you have. Without that information can't say much more as no one else can on BH. If you take the plunge you'll get loads of help from all sort of folk.. from SE's and seasoned builders with 40 plus years of exerience for example.

Here is part of my structural work and my wifes interior stuff.. we have yet to finish it off. This is an ex council house that we have extended in East Kilbride. The photo below is taken from my old phone so take it as it is. Key points we resolved. The hob is in the island. The grill in the ceiling is connected to a 125mm duct and the extraction unit fan is mounted outside in the external soffit. The fan I robbed from a Client that was chucking away an old kitchen extractor.. and delivers 600m^3 extraction.. is sucks like a devil and is pretty quite. The two pendant lights you see over the hob will set you back £ 500 plus.. but when offset with a standard extraction unit the lights were a bargin. What you see is part of an open plan space. I started out as a builder.. then became an SE and evolved into a "desinger". The challenge for me is to marry good practical design with good cost effective engineering at an affordable cost and do something special! Now over the last couple of decades I've seen folk wanting these massive open plan spaces as these have been all the rage. But for most families with two kids and a dog they are not that great. Kids and so on want much more pricacy for example.. our work patterns are changing. Our house is designed so that the social spaces are clearly defined. We have opted for other spaces that allow us to work from home, have a space that is entirely different. It's not for all but it is worth a think about. Here is a diferent view. The wall cabinets at the far end are from the 70's and sit off the floor.. The dining table is rosewood with space for 12 when extended.. the chairs contemporary. While the interior design may not be to your taste some key features are the shadow gaps in the vaulted ceilings. I set them myself and did the plastering but it allows us to easily change the decor in a weekend. You'll notice some boxes in the ceiling.. there are some pretty big steels hidden there.. but we accepeted that and use the boxing in of the steels to define the different spaces all be it open plan. Pick a kitchen that is not going to go out of fashion. Mine can be easily changed! Gray is not a good investment. If you look at my photos it may give the dry heaves! but think.. how easily could Gus strip that down and totally change the theme in two weekends.. and that is why I do this as a day job and you could be left with a crap gray kitchen!

Well done Ben that brief looks pretty good. The cost is middle of the road. Yes you'll need to pay the vat but hey ho. Make sure you meet them on site. Come armed with tea/ coffe and buns and a list of anything else. If near a road get some level of manholes etc, water toby cover levels and so on. Seriously and extra hour or two on site at this stage can save thousands later. From my end once we get into the detailed design we often need levels for obscure things.. it causes delay an uncertainty. Uncertainty = added cost and as designers we need to be conservative when there is a lack of quality information. Most folk want to help and will spend extra time if the Client engages. You can also get the gossip! and that can be invaulable later on. The gossip is things like what other sites have you seen nearby when work gets underway.. the ground.. who is the water board guy.. is he / she a wanker or pragmatic? As an SE I often refer to annecdotal evidence to back up some of my design decisions! If you feel they have engaged offer to pay a bit extra! Usually folks will say thanks but don't need more money! or just say and extra hundred in cash will cover it! To put this into context.. if you can save one day for a chippie or ground worker on site at £250.00 per day you get your money back! At this stage of the design you want to aim for the best quality of information you can get. I see this all the time on BH where folk skimp at the beginning and pay dearly later on. I'm not pelting folk self building as have done it myself when I was young. It is really hard to get the basic design info cf going to TF companies and so on for a guide price adding up the sums and hoping for the best.

Well done you for going for Geocell. I've worked with / designed for another member on BH using this as an option to EPS / XPS but in a slightly diferent context. All reports back so far are good! Can you post some detailed drawings and your target U values and edge details of what you propose. To be clear.. that means all the details. I'm interested but I'm not here to guess about what you want to do.. it's part of my day job as an SE and hobby so if you want a hand then please provide more quality information. Just as an aside.. The WYE system here: https://www.mikewye.co.uk/product/glasscrete-floor/ Is for a breathable floor. Now if you are on clay and you compact the shit out of it then you no longer have a breathable floor unless you ventilate at the sides big time! Love what you are doing, excuse the brevity!

Great comment. I'm working with someone at the moment who has decades of life experience, a technologist who can easily grasp both structural and Architectural design concepts. They are managing the design process very well. I'm chipping in with a bit of SE design stuff and being a bit of a devils advocate in terms of the over all design elements of the project. Also like many self build the design evolves particularly say in terms of drainage / buildability = cost. I think it can be helpful to have someone who does design as a day job who you can call up and chew the fat with.

Just asking.. any chance of a free pizza?

No I've not. Your comments can be viewed in different ways. There is a fair bit of hostility on BH towards Architects on BH. Lets leave it at that and have some fun designing and doing stuff.

The key here is to talk to the surveyor.. tell them what you want to do.. take their advice and offer to pay a bit more and ask them if it is worth paying a bit extra for a bit more service! For a bit of context.. when you get round to tendering.. one experienced operative on site can cost 1.0k plus a week... an extra £300.00 to the topo expense can really save you a lot of bucks. I've been on BH for a bit and totally appreciate how hard it is to nail down build costs. Everyone want to break things down into work packages.. like you are shopping in Asda. Self build does not work this way any longer. The people aspect is key to driving down cost these days. That takes time and effort... like serious effort and it is a massive learning curve to even get a grasp of the basics. BC, planning delays are costing us a fortune, I factor in now a dealing with "twat time" in terms of planning and BC interaction. TF companies etc are having to watch their costs.. and are delivering less on the design input.. eventually they will start to realise that service is the key. I see this as an SE. I totally get the excitement.. wife and I were away for my 60th this weekend.. passed by a distressed plot and she said.. let's buy that.. I'm like.. ok but let's make sure we don't loose our shirt!. Now what happens is I do an absolute pile of research and dilligence that I do as a day job anyway. But folk on BH often don't want to pay for that or expend the time learning about this.. and then find themselves in trouble. Years ago when I first started unless you were a complete idiot it was hard to lose money on self builds / flats / renovations / developments as property prices were increasing rapidly. There is much less room for error now and if you want to make a go of it you need to put in more work. It's shite but the rewards are worth the effort. Getting prices from kit companies, ground workers, sparks etc is no longer good enough as they are getting pelted by market forces.. they are putting too many caveats on what they are doing and it does not work as well now for the novice self builder. I'm still thinking about how I can explain in a better way of executing the mechanics of this in the current market. Post for another time.

I've followed @ETC for a while and he / she have contributed lots to BH. I've learnt loads from ETC. @Bozza wind your neck in and look at the contribution @ETC has made to BH, the time spent helping folk and the experienced based comments that ETC makes. I would at the very least get in touch with ETC and sound out!

All comments accepted. I went a bit overboard right enough. Interesting you are an Engineer that now flies for a day job... how did you get from A to B? There is another member on BH that does the same as yourself. Great bloke.. attention to detail is impressive. One of my family flies fast jets.. retired, appreciate the way you filter stuff. Golden rule seems to be.. don't crash. Well done with the oven.. it's all about the food.. who cares what the render looks like.

Aye ok.. true but what gets my goat is there are loads of folk advising on structural fixings and it is clear to me that they have no clue about the implications.

This all is happening in real time. My thoughts are to see if you can rack up expense for your neighbour as they have got all aggresive. Turn the tables. I would want to have a look at their foundations to see it they are relying on your land for support. Now we can make hay here as often builder never follows the foundation design when close to a boundary. You dig a hole and make them prove they are not relying on your land for support.. and that costs a lot SE wise and no SE is going to sign that off without a full investigation. I would check to make sure that they have the required fire boundary protection in place. I would also check any drainage runs and so on. Have they built over a drain that is serving more than one house and do they have build over permision for that? 80% of the time folk don't! They will shite their pants! This is a big lever. If they have done this with no build over permission then they are (expletive deleted)ed. Do their gutters over hang you property for example? Do they have an extractor fan vent to close to your property? In summary often we can find things that are non compliant on their side.. If you can find a street wise deisgner then they can maybe make this problem all go away. For me I would see where the land lies and if it look promising under your instruction chap their door and spell it out to them as an independant advisor, advise them (impartially of course) that they should seek professional advice as they could loose their shirt if they persist.

Hi all. There is lots of talk about concrete screws. But it is apparent to me as an SE that you have no idea of the loads that you may be supporting and the different behavoir of the substrate you are fixing into. Unless you are aware of this and the compressive loads from above, masonry bonding and the fact that a lot of concrete screws off the self are not stucturally rated then you need to shut the (expletive deleted) up as your comments are dangerous.. and stop giving advice that could miss lead the novice to Build HUb. if you want to suggest other fixings then I'm ears..

So cool.. only a lord of the sky could come up with that.. see Narcos!

Ok it's not worked out that well. If you are embarking on a big TF stick build project then you need a saw bench made from timber with a good top quality chop saw. You fix solidly the saw bench to any floor and at night you take the chop saw home so it does not get nicked. Expect to pay around £700 - £900 for a good saw and blade. On a big kit you need a saw with a 300mm blade that does compound cuts. Don't mince about. This way you can fabricate a TF frame to the same tolerances as a TF fabricator. OK so you are not 21 years old any more. Making Tf panels if working on you own.. on site and lifting them up. You square the panels with the odd OSB board. Then lift them and sheet after. To stop the sheets dropping you use a temporary ledger at the bottom and then tilt them into place. Now I'm an old codger I've figured out how to stick build a TF for the folk that are 60 plus.. and have done it myself.

Yes that sums it up but also the ground swells up.. some grund can swell / shring a lot.. several inches / cm! Things like trees and the desication of the ground are essential to know about. Nick makes a good point here. If your motivation is to achieve something close to passive then a raft is a good simple way of doing it. Yes the raft may cost a little more than a strip found but it can be much easier to build in some circumstances.. it's simple if you take care and lay the insulation and rebar correctly. All these things come with a lot of complexity. Say you are in a Radon area then a raft makes the Radon Barrier easier to detail out / buildability for example. Trees for example in clay soils can make things much more complex. But just say you have good ground and just want a raft as Nick favours and because YOU CAN and WANT IT.. no harm in that.. it's your house and your design decision. If you have good ground then this can be easy to achieve without chucking loads of rebar at the slab and making it massivly thick. You need some kind of floor anyway! It usually needs a bit of edge thickening in some form or another as folk want to put in big glass doors these days which cause point loads at the slab edge. One biggy that BC / NHBC ask about is cover for frost and height to DPC. Generally height to DPC from ground level for sensitive wall cladding is 150mm which is about 50mm less than the thickness of an ideal raft slab on good ground. Now add 300 mm of EPS to that takes you down to 350mm below finished ground level. Add say 150mm of type one and now all our materials (which are not suceptible to frost) extend to the min of 450mm required for frost cover. Box ticked. For all.. Raft slabs.. and a bit of info that may help. There are argueably three at least kinds of generic rafts. Within each type there are permutations. There are others but let's run with this for now. The main types are: 1/ A rigid raft. This tends to be a bit of a beast. We may use this in a domestic context where we have past mining that can cause the ground to move / crack horizontally at the surface. This used to be associated with long wall mining where you get a rolling wave of horizontal movement in the ground. We don't often design this way now in a domestic setting.. as they shut all the mines long ago. 2/ A semi flexible raft. Here we thicken the edge a bit but if you have heavy walls the EPS say at the edge compresses too much which causes the edge of the raft to rotate. To stop the rotation we reinforce the slab so it carries some of the vertical loads and stops the rotation of the edge. 3/ An edge thickened slab. Here the thickening at the slab edge deals with the frost cover and the differing line and point loads around the slab edge. The slab it's self is just designed so it does not crack thus has a light reinforcing mesh. Now within all these generic types there are permutations and the design is often driven by how good and consistent the soil is under the whole thing. If we have ground that has local soft spots then the edge of the slab and internally often needs to be thicker so it can span over the soft spots and thus needs more reinforcement. In summary it's a pretty complex undertaking in term of the structural / soil things you need to know about . but the solution is often simple once you draw it out. The main thing is to spend a bit of time and money understanding and investigating your ground as this reduces your risk and helps you design the right way. With a fair wind a raft slab does not always cost a lot more when you take everything in context.

Ask what would you home insurance say! Do you think they would pay out if your only arguement was.. well other folk have done it? Builders often tell you what you want to hear not what you need to know.