Mbu2ns Posted February 3, 2023 Share Posted February 3, 2023 Hi guys, looking at a SIPS extention, single story to the rear. its going to be strapped and boarded and rendered to match house (externally) inside strapped and sheeted with gyproc i want to have a suspended timber floor so i can run water etc underneat. does anyone have a drawing/sketch of what the founds should be like for this this is the bit im not getting my head around. 2nd question is the house before i moved in had EWI rendering done, can this be cut away or do i just make fixings through this into original brickwork. cheers mick Link to comment Share on other sites More sharing options...
Iceverge Posted February 4, 2023 Share Posted February 4, 2023 This details would do. Any particular reason for the SIPs and the suspended timber floor? You can just put ducting in the insulation layer under a concrete slab for pipes etc. Mind you I like suspended floors, more forgiving underfoot. You'll need to cut through the existing insulation to fix to the masonry beneath where the walls meet. Link to comment Share on other sites More sharing options...
Mbu2ns Posted February 4, 2023 Author Share Posted February 4, 2023 Hi mate, thats is what i was looking for, suspened timber......its what the house has, air bricks etc, the cold water main runs in the back, i have power and data cables going to garden room at the back, also suspended timber i can work with ( have experience with) i had a different build up idea in mind outer block that sips would sit on the inner skin that would have wall plate and joists to sit on. thans for the info requarding the ewi, i have an architect coming over, but its good to know where i stand and what would need to be done. cheers mick Link to comment Share on other sites More sharing options...
Iceverge Posted February 4, 2023 Share Posted February 4, 2023 You may run into splashback issues if you have any timber exposed like the picture if the bottom is not at least 150mm above ground level. This might mean digging your garden to 450mm below the floor level to get the appropriate clearance. Not ideal. Another's option would be to use rendered EWI on the extension to match the existing house. The structure of the extension could be timber or blockwork. You could get away with less of a drop to the garden and better thermal bridging characteristics. Say, 15mm plasterboard and skim 95mm studs at 400cc with rockwool 35. 11mm OSB taped externally as air barrier. 120mm EPS 33 taken down to below the foundations. Render. A U value of about 0.18 at 250mm thick. Link to comment Share on other sites More sharing options...
Mbu2ns Posted February 4, 2023 Author Share Posted February 4, 2023 cheers for the info ive attachd a paint drawing i did to show you the build up idea i had lol feel free to slaughter it =)) the reason for sips is its gonna be only 3m out from the house ideally to make a dining room and downsatirs shower room cheers again i appreciate you taking the time to reply mick Link to comment Share on other sites More sharing options...
Iceverge Posted February 5, 2023 Share Posted February 5, 2023 You'll loose lots of heat through this junction. 22 hours ago, Mbu2ns said: the reason for sips is its gonna be only 3m out from the house I'm not quite sure I follow you here. Have you discounted masonry and/or stick build? It's tremendously advantageous to be able to pop down to the local merchants for a couple of timbers and/or blocks., especially on a smaller project. What kind of U value are you targeting? Link to comment Share on other sites More sharing options...
Mbu2ns Posted February 5, 2023 Author Share Posted February 5, 2023 Hi Its more about maximising the space available in the room with it being so small, 3m out isnt really a big dining area (2 adults, 3 kids) also speed of errection im open to ideas on the construction, the U value doesnt really bother me, the house is a 1950's built and not insulated except the EWI, I have done full heating upgrade when i moved in and the extention area would have UFH Cheers again mate Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 5, 2023 Share Posted February 5, 2023 What size joists are going in the floor, and how much insulation are you installing? The UFH will need a significant amount of insulation under it to perform well without huge running costs. What will be supplying the heated water? Existing heating system T'd off to a single room UFH kit? Link to comment Share on other sites More sharing options...
Mbu2ns Posted February 5, 2023 Author Share Posted February 5, 2023 I do UFH jobs regularly, so i dont think it will be an issue, insulation will be cellotex/kingspan and see if i dot thing it will work i will just run pipes for a rad since i will have a suspended timber floor.....hopefully haha cheers Link to comment Share on other sites More sharing options...
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