Conservatory floor....

[Themeaney]

I am doing a conservatory and am up to the laying the slab part. I already have a slab of concrete about 5 inches thick from previous owners use, a drive. I am have 5 inches to play with (settle down!!) and am thinking of running joists over a damp proof membrane, and then floor boarding out with good quality floorboards. I shall use some insulation between joists, prob kingspan. Is this a wise idea? I see it as a pro as I don't have to lay slab and wait for drying, it gets my floor done in one easy stroke and will look good. And I already have huge slab which I really don't want to dig up, only to re lay the same

Any thoughts?

Ta

 

[loply]

Do you mean to say that inside your newly half-built conservatory you have a concrete driveway? Did you cut/smash through it to lay foundations, or is the conservatory literally built off the driveway?

Regardless, probably worth comparing the costs of joists and floorboards with the cost of the requisite volume of concrete, and just go with the cheapest. If you're going to be tiling it concrete has less risk of tile problems.

 

[Themeaney]

Hi, I did dig footings and do that part proper, yeah it's over a driveway of a depth of 5inches solid concrete. It's 8x5 m, so pretty big, ican get my paws on joists FOC, but will have to pay for kingspan or xtratherm, but if I poured a slab, couldn't accommodate insulation.

 

[loply]

So if you've got a conservatory with proper foundations but it just so happens to have an old concrete driveway inside it then I don't see why you couldn't put in a suspended timber floor as you suggest.

I would hang the joists off the walls though in the usual manner, I wouldn't rest them on the driveway, in case that's what you're thinking. Doubtless it won't move but why bring it in to the equation at all?

Having said that, is 5 inches enough for the span you need from the joists?