Flooring design & construction

[Midwest]

Apologies mods, feel free to move my thread elsewhere, couldn't seem to find anywhere suitable

Wondering if there's any knowledgeable carpenters here. I'm converting my integral garage to a habitable room. Unfortunately I only have 80mm finish floor level, to match with existing ground floor. In that I'm also having to fit services. I also have to meet the appropriate U value. I found some 20mm insulation by Kingspan that will achieve, which uses a wooden floating floor design.

At the bottom of all this, I will only have space of 27mm for my services, which I'll batten out and cover with plywood, which I can only have 9mm thick. So my question is what spacing for the battens should I go for, to provide a firm base for the floating floor above?

 

[Mike Johnson]

A multiple of 1200 x 2400 I would suggest 300mm.

 

[telectrix]

you could always fit in a step, and when Mrs. Midwest falls over it, ask her if she enjoyed her trip.

 

[Pretty Mouth]

Could this be done by not having a service void? ~60mm insulation, 22mm chipboard, and just neatly chase out to the necessary depth the underside of the insulation where your cables and pipes run? (I'm not a knowledgeable chippie, so as much a question than a suggestion). You'd prob have to go for larger cables to get over the derating.

 

[ferg]

Ask @Baddegg I believe he has some wood butchery skill.

 

[davesparks]

With 9mm ply I think the answer is as close together as possible. 9mm is a bit too bendy to really be any use for this application.

But having said that the insualation and floor boards will help span the gaps.

Thinking about it gluing the insulation to the 9mm base layer might work to stop so much bending between joists, gluing the floorboards to the insulation would help too but I'm not sure if that's allowed.
The ply/insulation glued sandwich would be similar to something I've seen done successfully before

 

[Baddegg]

With 9 mm I’d go down to about 150 centres @Midwest, Just make the strength up with cross bracing/noggins and a few cripples down Ward where you can fit em, glory of doing ya own place is you can do stuff you’d never get away with on site, you could always go with smaller timbers sistered up and lots of cripples then use a T&G chip board flooring staggering the joints, glued and screwed with a polyurethane glue....another option is to lay out ya services and work around them, effectively notching the joists from the bottom (bridging) over the cables etc, long as the lists are sat in the floor (assuming there’s a Dpm in there) it won’t matter how much material you remove then just battern between the joists to the depth of ya insulation you keep the air void...

 

[DPG]

Daz is now Googling 'cripples'.

 

[davesparks]

@Baddegg for those of us who are mere amateur carpainters what is a cripple?

 

[Baddegg]

A short piece of timber at the centre of a joist, at right angles to it, once the joist is fixed either end pull up on the centre and fix the cripple to it and down to the floor, one each side of the joist if needed will take the deflection/bounce out of an undersized timber effectively halving the joist span, do it all the time in old house down here wher the joists have sagged due to being ancient and undersized for the span, also used it a lot on concrete conservatory flooring where the customer wants some insulation in there but doesn’t have much height to play with bit like @Midwest...just googled it to see if I can give you a pic and I can see where some confusion may come in, I expect they have different names/terminology all over the country, that’s just what my grandfather and dad called em so......
[automerge]1596482592[/automerge]
Another option depending on budget is to look at a system of conservatory flooring called durafloor, it’s a steel frame made to you specifications, you could easily get the voids you need with that and probably get thicker insulation in...

 

[Leesparkykent]

Use thicker pir board, notch it or cut it around services then float caberdeck across it, gluing the tongue and groove with D4 glue and leave an expansion gap around the perimeter and cover the gap with skirting.

 

[Midwest]

Thanks for the replies. I want to keep the floor heights the same as the ground floor, so 80mm to play with.

I've had to get planning approval and a building notice, so the BI wants to inspect the normal things during build, which includes insulation. The room is going to be a cinema room, so as well as insulating it to building regs, the walls, floor & ceiling have to be acoustically treated. Could just use headphones I suppose.

I'd prefer putting services (mainly av cables in the floor) in the floor, easier to add too. I'll install some plastic trunking. Less that's in the walls, the better. This is the construction detail for the floor insulation;

Kingspan OPTIM_R

There's only about 36mm, below that lot to play with. @Baddegg think the durafloor is gonna be too deep?

 

[Baddegg]

Apologies @Midwest it’s called durabase...as I say depending on budget steel will give you a lot more strength with much smaller dimensions...

Durabase Modular Base & Wall System | Conservatory Base | Extensions

Explore our range of innovative modular bases as a way of extending your property. Our simple solutions come in a kit. Contact us to discuss pricing.

durabase.co.uk

 

[Midwest]

Apologies @Midwest it’s called durabase...as I say depending on budget steel will give you a lot more strength with much smaller dimensions...

Durabase Modular Base & Wall System | Conservatory Base | Extensions

Explore our range of innovative modular bases as a way of extending your property. Our simple solutions come in a kit. Contact us to discuss pricing.

durabase.co.uk

Thanks I’ll make contact.