Gus Potter

I wish BH had a spell checker. I just can't be arsed checking my dyslexia bit and spelling when I'm writing about stuff as a hobby. For all, my grammer and spelling may be a bit off when I'm off duty.. but neglect what I'm saying at your peril.

Hi all. The party is over indeed. I'm going to lay this on thick as it's time. I've picked UFH first but will turn to PV in another post. But to wet your aptetite! I've argued on this forum for a long time that underfloor heating is the bees knees. I've done this and worn the tee shirt. Long before most of you were in short pants. So if any of you can tell me how you installed and designed an UFH 22 years ago on a self build then I'm all ears! I would love to hear from you how we all flew by the seat of our pants at that time. I do hope that there may be one person. Many think they have invented the UFH wheel.. well you have not! The Scandinavians were at long time before the Brits.. I've made the case for simplicity and the need for UFH (the pipes in the slabs) to last the lifetime of the building, the cost of maintenance, reacting to how technology will evolve in terms of boilers etc. BUT what is in the concrete floor is a FIXED ASSET! Just like the walls and the roof! I also happen to be an SE who has actually been designing these slabs, insulated rafts to work with UFH for decades. So If there are any on BH that want to have a serious structural discussion with me then I would welcome that. You can ponce about with your weather compensation as much as you like, the flow rates.. your controls and buffering.. but see.. your heating has to work for 50 years so until you can make that arguement fdor life time performance, then I'll write down the value of your house if the pipes in the floor are not designed to adapt. SO GET A GRIP! I can and estate agents will also take a dim viw on a house value! Now some may just want to have a house that is a hobby, that is fine and I'm ok with that. But actually that may also make your house unsellable! Seriously.. you need to WAKE UP and smell the coffee, surveyors et al are clocking this so your hobby might come at an unexpected expense! Don't trust me. maybe ask a valuer? What I'm not OK with- if your house gets a loss of value as you have played with (and it is playing) home automation / complex UFH controls then that is a price you pay. But if you try and sell your house to some unexpecting young couple.. you can f... off., and I'm going to go hard on you! You are not going to sell your house to my kids! Advance Foundation technolgy have grasped some of it, Tanners in Ireland are competant SE's but no one has actually put all the bits together! The thing for me is that I want to design and build stuff that lasts, that delivers profit for self builders and that encourages young folk to enter the market, that benefits society. It's not a big ask? But as a designer with lots of real life experience I want to help young folk see the wood for the trees. I want them to get on the self build ladder on the self build ladder, I did it on a shoe string and that is why I keep pushing the simple stupid... as that means you can get a wider coice of Contractors.. which drives cost down. That is why I often push against the UFH complex thing and other stuff. It's also basically bonkers, but a lot of tecky folk on BH can'r see beyond 5 years.. So in summary I would like to see a lot of experienced folk on BH saying.. this works and if you are young folk embarking on a self build, on a limited budget this can work for you to. OK this is not going to go down well. But the life and future of BH is in the young folk, that are strapped for cash.. This for me and is why I'm still here.. I want to help and this is my hobby. To enthuse young folk, we need to solve problems, use our experience to say this can be not as hard as you think, if you take our advice, but at the same time give a bit of tough love if need be. PV is following much the same cycle..

Nick. I made my last post as I got a feeling that something was not right, it smells bad to me. I think why did NCX.. come on BH in the first place with some random generated name? Yes, we have not seen the drawings, the steelwork may be a small element. So here is a thing. Say we can save NCX five grand or potentially a lot more. and then say.. you got lots of help on BH so make a donation of 20%..

Each to their own Russell. Pesonally it looks like you have gone well over the score. Never mind so long as it works.. that is the main thing.

Ah, I'm going to take wide view on this, a bit brutal at times but I've put my claims hat on and explore if you have grounds for pushing back. I'm going to make some assumptions, but these you can explore yourself / mull over. First thing is I'm assuming you are a domestic Client, you have an element of protection under the consumer protection act. If your builder has worded their contract unfairly then they can be a bit stuffed as the law in the UK is more supportive than not. Next. Did your drawings show an opening with some steel? As you are a domestic Client and probably don't have; detailed drawings, a QS, probably not a recognised building contract then you still have a bit of protection as again.. your are a domestic Client. There is an argument in law that says.. as a domestic Client you can reasonably expect that a competant builder should be able to account for all the work even if it's not shown on the drawings. I do this as a day job (SE / designer and while we can be nice we don't take pish from folk when they step over the mark) and that includes a clause that says.. not every bit of (down to the last nails etc) the design is shown in detail. But even if that clause is not there you still have protection! OK that's the legal kind of bit. But how to you go about ascertaining if the builder has charged you too much? The steel cost may vary a bit but the big costs lies in how you tie the steels back to the building and any foundations below.. these bits can be very labour intensive and that is where the real cost lies. This cost can far outweigh an increase in steel weight. To dispute this you need to be able to look at these ancilliary bits and compare with what it would be a reasonable expectation from a competant builder. I'm just letting you know what has worked for me in the past when representing Clients when questioning builders costs. Now that is a lot of money when you look at the way it's presented! For all DIY folk.. the amount of money is relative in my book, I started out in life a bit skint so every pound was a prisoner. So I wonder is ( £28k + 10k ) plus vat in the grand scheme of things something you can live with or is it really going to hurt you? Do you feel you are getting ripped off? or do you feel that your builder in general has done a good job.. there is good will on all sides and it might not be worth not rocking the boat? Now is the time to maybe say to your builder.. and tie them down to their guarantee for the work. There are a number of ways of skinning this cat! If you feel you are getting ripped off then the first thing is to ask.. how much by and how do you go about getting a reduction in the invoice? Well, you have to be brutal if you can. Get them to finish as much as they can, for the least payment, then argue about the final payment. There are no friends in the desert!

A good number to get a feel for things for how much, at what rate you can discharge from your site, is mentioned in the SUDS manual CIRIA publication C753, when considering Vortex flow control (attenuation) for example is 2.0 litres per second. But what does that mean qualitatively. A discharge of 2 litres per second = 2 * 3600 seconds in an hour = 7.2 cubic metres per hour. So calculate how many mm of rain that is over one hectare in an hour. One hectare = 10,000 square metres. Thus 7.2 / 10000 *1000 (to convert it into mm of rain) = 0.72 mm of rain in an hour that you can discharge. Some of C753 also mentions 5.0 litres per second for example. The concept of SUDS is to make sure that what you build does not result in an increase in run off rate. Ok what does 5% look like say if you get 25 mm of rain in an hour? 0.05 * 25 = 1.25mm which is more than the 0.72 rate I calculated above. Now say you get a heavy down pour! So if we look at what @saveasteading is saying the rough sums kind of prove his point?

You have to start from somewhere, so try an Architect first if inclined to do so. Let us know how you get on, you have got some tips / hints so far on BH so that should aid your discussion. As always, try and enjoy the design process, it's not a competition! Keep us posted.

Have a look at the building regs. On upgrades I often have to have a discussion with BC in terms of what is "reasonably prcticable" In your case as you don't seem to be increasing the building foot print or the volume then this supports the "in so far as reasonably practicable" approach. The key to this is as you have clocked it is to maintain good ventilation, the more insulation the more ventilation you need, that's a rule of thumb. The other key is to tightly fit the insulation and use tapes to stop convection currents bypassing your hard work installing the insulation. Last is to install a good vapour barrier on the warm side to stop water gas getting into the insulation layer in the first place. Moist air does liittle harm.. the harm arises when the gas temperature lowers and you get water condensing out, we call this the dew point. The best way to get increased performance is to use insulating plasterboard on the underside but this may reduce the ceiling height. This works as you don't have the repeating bridging effect of the joists. Below is a link to Kingspan. You can play about to see the difference between insulated plasterboard and insulation between the joists. https://u-valuecalculator.com/gb Hope this helps and you have a bit of fun playing about with it.

Welcome to BH. D & G is a great place to live. You have a journey ahead, main thing is to enjoy it. You'll get plenty help and suggestion here and BH is a fantastic resource.

A structral requirement of the BC regs is that the windows and doors need to be positively fixed to the structure. Detailing this is difficult to meet the SE requirements. I'm not singling out anyone in particular as this problem is common across the board. We see loads of details but few that show the fixings and their capability to resist the wind loading on the glazing while accounting for head deflections and thermal bridging. In other words I think... first thing to do is to make sure your glazing is fixed so it does not fall out and hurt someone. On large openings check the head deflection from the structure can be accommodated so it does not jamb the doors. Then think about the outside weathering detail and then last the thermal performance in terms of cold bridging. I know it's not not de rigueur but what do I know? Well I can tell you.. if your glazing is not properly fixed then no SE sign off. Here is a suggestion. Accept that you have to compromise, live with a bit more thermal briging and add a bit more insulation elsewhere. You will be not happy if water starts to leak in driving rain so that is why I put weathering as my second point. Threshold details can look great on a drawing.. but you need to make them idiot proof as few folk will keep out leaves, moss etc. You also need to make them buildable which many details are clearly not. Has your Architect put themselves in a builders shoes? How do you achieve this on site and how do you water proof the ends? If it's too complicate you'll likely end up paying more for something that probably won't get delivered on site.

Thanks for posting, its a refreshing topic. Fundamentally, on the face of it, what you are doing is not that difficult.. the technology and designs are well proven. Where it becomes difficult is when folk don't reasearch or question the advice they are getting. But you are, so hat off to you. For me (SE hat on) I would want to understand the Architectural design; how is it supposed to work, how is it supposed to look, how does it marry with the house, garden and how does the space get use in terms of circulation, when you have a party / entertain. Then delve down and look at the choice of materials and why they have been selected Architecturally. Once I get a handle on that then I can start to think about how you engineer that to stay within the Architectural envelope and material choice you the Client desires. This is common when you have a high water table. The piles more often than not are not subject to a lot of tension in normal use, but if under designed with a high water table then the middle of the pool slab can tend to lift up first when you fully empty it. This causes cracking which over time leads to leaks and so on. This gets worse over time, but by then the contractor is long gone. Then if things are bad the whole building can float up and out of the ground! Tension piles and restrictive maintenance clauses can vary, in other words pool design can be a bit like the second hand market, prices can vary a lot, so you have to be really careful that what you are buying is going to do the job you want with the life span you want. When we have chlorine SE's will usually err on the safe side and treat this as an aggresive environment. The thing is that while you may control it the next owner may not. This comes under our Civic responsibility. At some point you may want to sell the house, a surveyor may say.. how much is this pool going to cost to maintain over the next 40 years. If there are too many caveats then it may put a buyer off. The extra cost of protecting your asset is often not as much as you think. For me I'm interested in your ground conditions. @markc knows a lot about this stuff, probably more than I! Keep up the good work posting!

Hope this helps. The design of these things needs to start with the ground. This is a large investment. One way of thinking about this is not just in terms of the weight of the structure on top, nor the weight of the pool when it's filled with water, as water often weight less than the soil you dig out, but what happens when you want to empty it for maintenance. If the ground water is high then the "pool box" is going to float out the ground, we call this buoyancy. Just say your overall excavation with insulation under the base of the pool is 2.2m. The buoyancy will be about (very roughly) (29m + wall insulation, say 29.5m) x (7.0 + wall insulation, say 7.5m) x 2.2m (pool depth + floor + insulation) = about 487 tonnes! From that you deduct the weight of the walls below ground + the wieght of the structure on top. The type of structure you have is not likely to be heavy enough. OK, you may say, well I'm going to dewater it when I want to empty it. But as you're close to the neighbours the dewatering may cause a problem over the boundary or cause a problem with the existing house. Then, as others have pointed out, you have a chlorinated liquid in a building which is not a great fit with many common building materials. This takes time to think through and you do need good professional advice.

But how would you have known that? The only reason that I know is that I've been in this for a lot longer than most folk on BH, I'm also a self builder, an SE, past Contractor and know how things can go wrong. I kind of have a bit of an advantage, call folk out but try not to be too much of a smart arse. That said the previous just sounds like I'm a smart arse! Ok for all. the motto is, build in redundancey into your UFH pipes, loop CAD etc is nice but don't forget the pipes over lap for example, so don't go for a too thin a screed. The pipes will over 50 years get a bit of furring, so pipe up anyone that can claim otherwise.. come on.. be brave! Or are there any folk that think that UFH should only last 15 years? What then? By all means go for weather compensation, home automation.. but just remember that when you come to sell your house a surveyor may not appreciate your fancy and possible rapidly outdated controls and software. Yes you may have done calculations but what happens if the new owner puts a rug on the floor! moves the furniture.. Basically what I'm saying is that a lot of UFH heat loss calcs are pish ( most are just a guide as to how it might work in real life) as they don't take into account the life cycle of the house. If you want to get teccy then we need to look at the soil dumpling below the insulation, the floor perimeter insulation, a large sofa does block heat which does tend to play havoc with weather compensation, I can pick faults in this all day long.. Much of UFH is about practical design, like foundation raft design, part thoery and part an art.. Close up the pipe centres below large areas of glazing, run one pipe under kitchen units just to stop condensation for example. Just imagine if it was your kids that then go an buy the house and it turns out that the build had been designed on two retired folk that never have kids opening doors etc! and there is a bunch of home automation that no one can work or even if they can get replacement parts. UFH can be great but is the best way of designing it is first to recognise that is in a blunt instrument, on / off and keep it simple.

You need to cough up and pay for an SE / Designer who knows about this stuff. Try and find a designer that can hold your hand and walk you through the things that need to be considered, how you design the different bits so they fit together and work. They will also help you put together the different work packages so you pay a fair price. The design and execution is much harder than you are probaby aware of. I have this on my website from Ruskin but is is worth a revisit. “There is hardly anything in the world that someone cannot make a little worse and sell a little cheaper, and the people who consider price alone are that person’s lawful prey. It’s unwise to pay too much, but it’s worse to pay too little. When you pay too much, you lose a little money — that is all. When you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do. The common law of business balance prohibits paying a little and getting a lot — it can’t be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if you do that you will have enough to pay for something better.”

No, because I feel if you want to save money then you need to put in the leg work first, there is no free lunch. Your starting point is to learn how you put together a timber frame, how the lateral stability system works and so on. If you make a good go at your TFand post your drawings then I may chip in as an SE / designer to give you some tips etc.. but I'm not going to share my intellectual property with you until I'm sure you have done the leg work.