Flush floor finish foundation

[Ps67]

Hello,

What is the proper and most cost effective way to do a foundation if you are looking to have a flush floor finish with external ground level while bearing in mind some form of dpc is needed

This is for a steel frame garden room (single storey outbuilding).

So I.e. no subframe above ground level that would take away 150mm or so internal height from the 2.5m height limitation. And if doing a concrete pad this would have to finish at the same height as external ground level.

 

[tell80]

Its kind of difficult for me to understand your post but fwiw Bldg Regs state that a DPC must be 150mm above ground level.
Why not sketch a rough section view of what you propose pic it, & then post it on here.

 

[oldbutnotdead]

So you want your finished floor at ground level? What sort of internal cladding are you planning for your steel building? Does said building have a floor or are you having the slab as finished floor?

 

[Ps67]

Hey, thanks for getting back to me.

No internal cladding, Plastered and decorated on the inside. Externally it's sheathed in 75mm pir x 11mm osb and then cladded.

And we build up from the concrete base, with insulation board and a finished tile floor

 

[oldbutnotdead]

Your construction details are still rather vague. If you're putting insulation on top of the slab then the slab top would need to be below ground level. Tiling on top of insulation isn't going to work- you'd be better putting the insulation under and around the slab then tiling to the concrete.
Stick some sketches up so we can see what you're talking about.

 

[Nige F]

Its kind of difficult for me to understand your post

Have a lie down then

 

[Notch7]

Hello,

What is the proper and most cost effective way to do a foundation if you are looking to have a flush floor finish with external ground level while bearing in mind some form of dpc is needed

This is for a steel frame garden room (single storey outbuilding).

So I.e. no subframe above ground level that would take away 150mm or so internal height from the 2.5m height limitation. And if doing a concrete pad this would have to finish at the same height as external ground level.

the best way is to cut a pathway across the side with the doors and a retaining wall of 150mm for the ground to butt up to. It allows you to have a convention 150mm from ground level to effective DPC level

you need to consider surface water drainage to do that.


If you want patio level same as floor finish, so a flush cill then you need an ACO threshold drain, so you will need underground drainage Pipes to disharge the water into. You still need to deal with the abutment of the rest of the building where it meets the ground - maybe a conventional ACO drain. It requires very careful detailing or you will end up with a damp building or leaking.