idris

Thanks. The roof panels are very nearly flush with eachother on mine and I doubt T&G would be noticably better. Are you suggesting just an external membrane or an internal vapour control barier as well? The company that supplied mine doesn't include an internal membrane with their full kit (though I only got the shell from them). I'm in two minds as to whether to fit one of not.

Not answering your question I'm afraid, but ... I'm doing a similar build and was lead to believe the EPDM could go directly onto the SIPs roof panels. Were you advised this was a bad idea?

I have UPVC over-sills fitted over original 1950s tile sills, all of which I'd like to replace with wood. It looks like the UPVC over-sills would come out easily. How likely is it that the tiles will remove easily, or are the windows likely to be fitted over the sills?

It was a phone call, not a technical document, I had several other questions and, at this stage I wasn't that bothered about specifics. There is no reason to assume that proper calcs haven't been done and adequate fixings aren't spec'd.

There was some mention of size, but I forget what it was.

In case anyone needs an answer to this in future, having spoken to the lot supplier I'm looking at, this is how it works: The SIPs floor panels are joined by solid timber (rather than the insulated joining pieces I've seen elsewhere) and bearer beams are supplied to sit between the floor panels and the ground screws. The recommendation is to use ground screws with the flat SIPs type top plates and these are sited under the joins on the floor panels. Self tapping tek screws are then driven down adjacent to the panel joints, through the jointing timbers and the bearer beams and into the ground screw top plates.

I guess the mitigation is that it's a ******* big "garden room" and it doesn’t get that windy this side of the Yellow Brick Road.

Interesting build video, not least as I couldn't see any mention of fixings between the frame and the ground screws. Their frame just sits on the ground screw top plates and the flooring panels slot into the frame. The implication is that a strong enough wind could lift the finished building off the ground screws.

@markc Don't worry - I know what SIPs, how they're constructed and how they fit together. I've just never considered their use in floors, as they are in the kits I've been looking at in the last couple of days. A SIPs wall is anchored to the floor pretty much the same as a timber framed wall - you simply bolt the wall's bottom plate to the whatever is beneath it and screw/nail the rest of the structure to the plate. But that doesn't deal with how a SIPs floor panel is usually anchored to whatever's beneath it. Even if the're faced with 22mm OSB (which I doubt), that's not a lot to screw into. So as far as I can see, especially with those plates, the intention is that the entire structure just sits untethered. @saveasteading I'm pretty sure you can dig a trench and get concrete pumped into it without any proper knowledge too. 🤣 Are SIPs over priced? In some cases, possibly, but for what I'm looking at, having built an insulated framed structure before, the increased cost is far out-weighed by the savings in time and (my or someone else's) labour cost.

These are the type of support brackets I've seen. https://www.groundscrewcentre.co.uk/products.asp?cat=Ground+Screw+Brackets It looks as though the SIPs variants are designed to have floor panels sitting directly on them, as opposed to those designed to take a frame. @saveasteading Your anti-marketing-hype cynicism is admirable, but I can assure you I've never set foot in a self-build exhibition and this is all the product of my own ignorance and misguided online research. But yes, access is a significant consideration. An alternative would be concrete piles, but I'm not convinced that would be much better. Why don't you like ground screws?

What I've seen has made no mention of a subframe, so that's useful to know. Now you say there's no such thing as a silly question but ... how does a frame make fixing the floor panels any different? There's still limited access from below and screwing down has the same issues. I can see at the edge of the structure you could use brackets a little more easily, but I can't picture how that's a big gain.

Doubtless a silly question for my first on the forum ... I'm researching fitting a SIPs floor onto ground screws but I can't seem to find any indication on fixings. Access to put screws up through the ground screw plate will likely be limited, and screwing down through the SIPs floor into the plate just strikes me as wrong for so many reasons. Or you could sit the building on the ground screws and just hope it doesn't move. Does anyone know what the usual way to do this is?