Garden Room Slab- DPM?

[charliegolf]

Hi All

I'll be laying a slab (4.8 mx 3m) shortly, to take a sips garden room, which will have a sips insulated floor, on battens. Is a DPM required?

Also, ready mix seems a mental cost round here for what seems like about 2.2 cu m;
So...
Is on site mixing feasible for a 4" slab with plenty of labour?
If yes, what ballast/cement mix will suffice?
Do I need mesh?

Sorry for all the Qs...

Thanks

CG

 

[Charlie George]

Your measurement works out at 1.5cu which is around 3 bulk bags ballast 20 bags cement, cost here NW £300ish plus mixer and labour, don't know about the sips panels, but would be good practice to include a DPM and mesh, do you not have a local barrowmix to mix on site what you need and do all the barrowing.

 

[charliegolf]

Ta for the reply. No, we don't seem to have barrow mix round here, S Wales. £300 ish is around half one of the ready mix quotes I got!

 

[noseall]

Hi All

I'll be laying a slab (4.8 mx 3m) shortly, to take a sips garden room, which will have a sips insulated floor, on battens. Is a DPM required?

Also, ready mix seems a mental cost round here for what seems like about 2.2 cu m;
So...
Is on site mixing feasible for a 4" slab with plenty of labour?
If yes, what ballast/cement mix will suffice?
Do I need mesh?

Sorry for all the Qs...

Thanks

CG

If the slab is contained/sheltered within the footprint of the building - yes.

If not and it protrudes past, try and get some membrane beneath the deck layer and turn it up the sides, prior to fixing the external clad.

We laid an oversize slab and sheeted it with a large piece of poly, before building the base. I made a 'ring beam' of 4" x 2" then infilled it with 50mm Celotex and floated the floor deck on that. Once the sides were built, I stapled the excess poly up the sides.

 

[^woody^]

You'll have difficulty detailing a DPM for a slab.

What does the manufacturer state? It may be a strip of DPC tacked to the bottom of the battens and a vented void.

Tamp and trowel the surface flat to avoid packing and twisting of the frame and floor.