Celotex for floating floor?

dearlouise

I'm planning on insulating a concrete floor in a garage type structure using celotex board insulation and chipboard.

I've read the main 2 ways are either to make a battened frame & fill the gaps with celotex (or similar) or just make a 'floating floor' where the celotex is placed on the whole floor then the chipboard on top.

Obviously the cheaper method would be the floating floor as I wouldn't have to buy wood for framing. It would also be a bit warmer I imagine as there is less wood and more insulation.

However... would the insulation take the weight of furniture & belongings? The conversion is going to act as a bit of a spare room. So wardrobes, lots of clothes, bookcases & books... will the insulation be able to hold that without compacting even further & causing the floor to be uneven?

27col

I fitted a floating floor in my double garage when I converted it into a flat for my son. Absolutely no problems at all. We put plastic sheet on top of the insulation and a coat of Synthapruf under it Then stuck the chipboard panels together by painting pva adhesive along the tongues of the boards. No fixings required as the floor rapidly becomes a huge immovable mass.
I was going to use battens but the Building Inspector assured me that the adhesive method would be fine, and it was.
It has been down since 1998.

System

you can put some of the celotex products under a concrete slab so I wouldn't worry too much about chipboard - the only downside is that you have no where to run services under the floor

brightontraveller

I'd go for celotex and ply t&g (Although £1-2 per square meter more you can leave as surface finish waxed, varnished etc so saves on floor covering If sheets have good grain pattern looks very impressive? ) rather than chipboard (hate the stuff ) Once celotex is down cut channels to run services e,g water, gas, electricity etc before laying floor covering *tip mark the channels on face side of surface covering for future reference ?Or if leaving ply as surface finish take picture of routes ?

dearlouise

Is it cheaper to stick concrete over the top of celotex rather than chipboard? How thick would the concrete need to be on top?

I'm toying between 75mm-100mm of insulation, but don't want to loose *too much* height.

brightontraveller

dearlouise wrote: »

Is it cheaper to stick concrete over the top of celotex rather than chipboard? How thick would the concrete need to be on top?

I'm toying between 75mm-100mm of insulation, but don't want to loose *too much* height.

I’d say cost would be higher as you're looking for “cheapest” chances are whomever finishes it would need screed on top it ? qadd floor covering etc, You can polish concrete leave a finished floor but that skill tends not to go with cheapest ?

dearlouise

It is currently a bare concrete floor. The original plan was to insulate & chipboard then carpet on top. So I wasn't planning on laying any more concrete.

But if that's cheaper than doing the chipboard, I'd consider more concrete. Had a look at self-levelling concrete in B&Q this afternoon and it's £18 a bag.

Plasterer

dearlouise wrote: »

It is currently a bare concrete floor. The original plan was to insulate & chipboard then carpet on top. So I wasn't planning on laying any more concrete.

But if that's cheaper than doing the chipboard, I'd consider more concrete. Had a look at self-levelling concrete in B&Q this afternoon and it's £18 a bag.

Use chipboard, screeding is more expensive. Also what you've seen in B&Q is self levelling compound not self levelling concrete and is not designed to put straight onto cellotex - it will break up as soon as you walk on it.