How to fill up my sub floor

BnB

I was out with the measuring tape yesterday evening and I've found out that I have between 11 and 12 inches to fill between my sub floor and my finished floor level. I have 6" of insulation ordered already. And I will be putting 3" of concrete on top. So that leaves me with another 2 or 3 inches to fill. The 4 options I can think of are....

1) Fill it with Concrete. But this would be expensive and a good bit of work. I would basically end up pouring the floors twice.

2) Put an extra 2" board of Insulation in. I would be afraid that 8" in total of Insulation would be unstable under the 3" floor and that in time, the floor might sag.

3) Fill it with sand (My Fathers suggestion). I would be afraid this would hold onto too much moisture.

4) Fill it with some grade of chips. This was a suggestion made to me by a lad this morning who has worked on a few sites. Apparently he has seen it done on a few houses before.

tusmaith

what do you mean by sub floor?

mr_edge_to_you

I would suggest a decision like that is run by your supervising engineer.

BnB

tusmaith wrote: »

what do you mean by sub floor?

By Subfloor, I mean the concrete that was poured on top of my foundations. The heating Pipes etc have gone down on it and I now need to fill it bring it up and pour the finished concrete floor on it that will have tiles laid on it etc.

BnB

mr_edge_to_you wrote: »

I would suggest a decision like that is run by your supervising engineer.

Oh God yeah. I'll be ringing him in the morning. But just want to get a few opinions here to know what my options would be.

tusmaith

in that case extra insulation would not be unstable, would be better than sand / chippings,
concrete to build up level would not be practical,
but as previous posted suggested, check with engineer

mossfort

why do you have to rise your floors 12" from the finished level of the raft ?
the normal procedure is to lay your insulation and screed over.
3" sounds very thin for a screed.

sunnysoutheast

BnB wrote: »

By Subfloor, I mean the concrete that was poured on top of my foundations. The heating Pipes etc have gone down on it and I now need to fill it bring it up and pour the finished concrete floor on it that will have tiles laid on it etc.

Do you mean underfloor heating pipes?

We have 2x100mm of insulation + 80mm screed + 20mm tile making up the floor.

If you're putting insulation down then try to cross-lay it, maybe you can swap the 75mm boards for 100mm ones.

SSE

BnB

mossfort wrote: »

why do you have to rise your floors 12" from the finished level of the raft ?
the normal procedure is to lay your insulation and screed over.
3" sounds very thin for a screed.

Why do I need to raise my floor by 12" from the finished floor...?

Of course it shouldn't be that way, but there seems to have been a mis communication somewhere between myself, the engineer and the block layer. I suppose that's the joy of going direct labour when you don't really know what you're doing. Still though, it's not the end of the world.

BnB

sunnysoutheast wrote: »

Do you mean underfloor heating pipes?

We have 2x100mm of insulation + 80mm screed + 20mm tile making up the floor.

If you're putting insulation down then try to cross-lay it, maybe you can swap the 75mm boards for 100mm ones.

SSE

Yep. We're pretty much going to be a carbon copy of that. We have all our pipes except the under floor down (water, waste etc). I'll put down my 8" of Insulation on top of that now (fitting the first layer around it) and then the Underfloor pipes on top of that. Then pour our 3" screed and we'll be tiling on top of that.

That's is what the engineer reccomended and I'm happy to go with it.

guideanna

we used gravel form the same company that supplied our concrete. Can't remember how many inches we had to fill up though.

sunnysoutheast

BnB wrote: »

Yep. We're pretty much going to be a carbon copy of that. We have all our pipes except the under floor down (water, waste etc). I'll put down my 8" of Insulation on top of that now (fitting the first layer around it) and then the Underfloor pipes on top of that. Then pour our 3" screed and we'll be tiling on top of that.

That's is what the engineer reccomended and I'm happy to go with it.

I think our waste pipes are in the floor slab.

Don't forget your edge insulation! We used 50mm all round the perimeter and butted the 100mms up to it hold it in place.

SSE

BnB

Went laying the insulation at the weekend. After putting down the first 4 inch board it became clear that we didn't need 8" at all. We had calculated that we would need it from looking at the height of the internal door frames. However, we should of course have checked the external ones (Which were fine). So we had to revert to the origional plan of 6".

Luckily enough, being a cheapskate, instead of buying 4" of Aeroboard and 4" of foil -backed quinntherm stuff, I had gone for the cheaper option of a 4" board of aeroboard, a 2" board of aeroboard and 2" of quinntherm. So I was able to leave out the 2" of aeroboard.

We might have a small problem with the internal door frames being about 2" too high but we'll wait and see when the floors are poured.