MartinD Posted November 6, 2019 Share Posted November 6, 2019 Hello all we have just purchased a Bungalow and plan to tear gown and rebuild. Council agree with this approach. Just starting to design it and thinking about all aspects especially on the energy efficiency front. look forward to using this Forum. Martin Link to comment Share on other sites More sharing options...
Conor Posted November 6, 2019 Share Posted November 6, 2019 Welcome. Demolishing and rebuilding quite often the sensible approach... Same for us. Any ideas or what you want to build? Link to comment Share on other sites More sharing options...
joe90 Posted November 6, 2019 Share Posted November 6, 2019 Yup, demolish and build something with loads of insulation (which you only purchase once). What are you looking to build and are the planners on board? Link to comment Share on other sites More sharing options...
MartinD Posted April 15 Author Share Posted April 15 Hi all, I look at posts but realise I joined in 2019 and haven't posted since! we still have not demolished after Covid and planning delays and then looking at a refurb option. However we now have an MBC timber frame on order for a PH spec House. We have had complications on the foundation as I wasn't happy to do the norm in our area of a piled foundation and now have a specialist PH experienced structural engineering co. on the job as well as our PH architect. We have a insulated slab foundation design with a big thickened section around the perimeter and across the centre to better spread the loads as our clay is not great but as our structural engineer pointed out when they visited the new house is no heavier than the bungalow and that has not sign of any cracking after 60 years! Demolishing is imminent hopefully and need to get foundation design finished sorting out drains and other penetrations in it. One point we are discussing is whether UFH pipes in slab a good idea structurally (inducing stresses and possibly cracks) but looking at this website there seems plenty of supporters. Link to comment Share on other sites More sharing options...
Nickfromwales Posted April 15 Share Posted April 15 2 hours ago, MartinD said: Hi all, I look at posts but realise I joined in 2019 and haven't posted since! we still have not demolished after Covid and planning delays and then looking at a refurb option. However we now have an MBC timber frame on order for a PH spec House. We have had complications on the foundation as I wasn't happy to do the norm in our area of a piled foundation and now have a specialist PH experienced structural engineering co. on the job as well as our PH architect. We have a insulated slab foundation design with a big thickened section around the perimeter and across the centre to better spread the loads as our clay is not great but as our structural engineer pointed out when they visited the new house is no heavier than the bungalow and that has not sign of any cracking after 60 years! Demolishing is imminent hopefully and need to get foundation design finished sorting out drains and other penetrations in it. One point we are discussing is whether UFH pipes in slab a good idea structurally (inducing stresses and possibly cracks) but looking at this website there seems plenty of supporters. Great choice with MBC, and please stop panicking about UFH in the slab! I've done loads with MBC / Kore etc with the pipes in there and not a sign of trouble anywhere, other than where I expected it (hairline cracks between ring beam and intermediate beams) and where we managed this by planning / design. The good thing with MBC is they are happy to oblige with penetrations in steel etc for the M&E side of things, and I work well with them to make the 1st fixes dead easy (ergo cheaper and quicker) for things like foul & waste water + MVHR. Had some exceptionally good AT results with their PH offering too, so I am sure you'll be happy . Listen to your SE btw..... Most stuff is already hugely over-spec'd / over-engineered, and if they're telling you to relax you should listen as that = ££££££ if you don't. Grade the hardcore from the demo and reuse on site too, that's what I'm doing on a replacement dwelling project (coincidentally also in Surrey!) which will save a load of money with the crane pad and temporary access roads. Let me know when you get cracking (and, more importantly, when you have a kettle set up) and I'll swing by to see how you're getting on. 1 Link to comment Share on other sites More sharing options...
saveasteading Posted April 15 Share Posted April 15 2 hours ago, MartinD said: whether UFH pipes in slab a good idea structurally I've done it on a large scale, twice I think, and it was fine. Just a bit of a risk if there were any leaks (breaking out a structural slab) or of a concretor walking on pipes and damaging them. Structurally it isn't any issue at all. More important is whether you want the slab to be thick and act as a heat sink, or be thin and more responsive. My preference is the latter: a thin concrete screed covered in lots of insulation then a top screed as your finished surface. 3 hours ago, MartinD said: to better spread the loads as our clay is not great Says who, if not your SE? 2 Link to comment Share on other sites More sharing options...
Nickfromwales Posted April 15 Share Posted April 15 3 minutes ago, saveasteading said: or of a concretor walking on pipes and damaging them. The pex-al stuff is crazy hardy tbf, and most UFH installs I do on heated constructional slabs have either us or follow-on trades walking on them, sometimes for days, without any detriment. Damage to this type of pipe has to be near malicious for this to leak. 2 Link to comment Share on other sites More sharing options...
MartinD Posted April 16 Author Share Posted April 16 Thanks for the input very helpful. The SE is the one who says our clay is not great and others would not do a slab on our site as they didn't seem to understand that our timber frame house which is not brick clad is going to be a low mass building. It is the SE that would rather we don't have the UFH pipes in my slab which is my preference as we will have the insulation below and around the slab. For putting the UFH pipes into the slab, looking at this forum we can use pipes etc from Wunda and get them to design it (ASHP company I'll probably use also suggests them) but who attaches it to the rebar - my groundworkers haven't done it before (they do groundworks for Baufritz and the like regularly so know who to do this type of foundation) so will need a bit of guidance if they are asked to do it. Link to comment Share on other sites More sharing options...
Thorfun Posted April 16 Share Posted April 16 1 hour ago, MartinD said: Thanks for the input very helpful. The SE is the one who says our clay is not great and others would not do a slab on our site as they didn't seem to understand that our timber frame house which is not brick clad is going to be a low mass building. It is the SE that would rather we don't have the UFH pipes in my slab which is my preference as we will have the insulation below and around the slab. For putting the UFH pipes into the slab, looking at this forum we can use pipes etc from Wunda and get them to design it (ASHP company I'll probably use also suggests them) but who attaches it to the rebar - my groundworkers haven't done it before (they do groundworks for Baufritz and the like regularly so know who to do this type of foundation) so will need a bit of guidance if they are asked to do it. we didn't put UFH pipes in our slab in the basement and i ended up putting between 25mm PIR on top of the slab and then fitting pipes to that and putting a 50mm liquid screed over the top. seems to work in our house. on the ground floor we have block and beam over the basement and insulated slab (EPS below the slab) on the 'arms' and put 50mm - 100mm EPS on top and then a liquid screed on top of that. house is lovely and warm so it can be done. as you're going PH i don't think you've anything to worry about in having the UFH pipes on top of the slab with a screed on top (if you ever need to turn it on that is!). just make sure you allow for it in your design so that your FFL is correct! Link to comment Share on other sites More sharing options...
Thorfun Posted April 16 Share Posted April 16 ps. here's our blog post on the basement ufh if it helps Link to comment Share on other sites More sharing options...
Nickfromwales Posted April 16 Share Posted April 16 14 hours ago, MartinD said: For putting the UFH pipes into the slab, looking at this forum we can use pipes etc from Wunda and get them to design it (ASHP company I'll probably use also suggests them) but who attaches it to the rebar - my groundworkers haven't done it before MBC install UFH in their passive rafts as standard, they'll even work with a design from your ASHP company but MBC will defo be fine without guidance. Look at your contract and you'll see it in there as an assumed 'optional extra' in the price. Link to comment Share on other sites More sharing options...
MartinD Posted April 17 Author Share Posted April 17 Thanks Nick, fully aware of the option with MBC but they aren't doing our groundworks as their foundation designer's didn't think it suitable for their standard foundation and they wanted it piled, hence we wnet to a another specialist Passive House SE. I have now found a local UFH installer that is experienced installing the UFH pipes to rebar quickly and at a decent cost so I have this back as an option. cheers Martin Link to comment Share on other sites More sharing options...
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