Oversite Question

[Glenn83]

Am after a answer as not to sure what is required.

My extension is starting and the floor is going to be suspended on joists and beams so to match the existing house, With the oversite do i still need to insulate it and concrete it or can it just be type1 and a skim of concrete, I assume as its not directly having the finished floor on it it can be the later. The just insulate the finished floor?

Thanks for the help

 

[Murdochcat]

Are you doing this yourself?

 

[Glenn83]

Yes I will be, I think i just found my answer in the building regs Part C,

 

[Murdochcat]

Just remember that your BCO will be interested in this

 

[freddiemercurystwin]

In this neck of the woods, where Radon is a possibility, BC would expect a sealed dpm under the oversite and for it to be linked (sealed) to a dpc in the wall (to form the Radon barrier).

 

[Glenn83]

In this neck of the woods, where Radon is a possibility, BC would expect a sealed dpm under the oversite and for it to be linked (sealed) to a dpc in the wall (to form the Radon barrier

I dont think that's a bad idea i may leave excess all round so the brickie can tie it in

 

[noseall]

Am after a answer as not to sure what is required.

My extension is starting and the floor is going to be suspended on joists and beams so to match the existing house, With the oversite do i still need to insulate it and concrete it or can it just be type1 and a skim of concrete, I assume as its not directly having the finished floor on it it can be the later. The just insulate the finished floor?

Thanks for the help

Freddie's comments aside - yes, a reduced layer of concrete is fine. MOT isn't really necessary.

@freddiemercurystwin

In this neck of the woods, where Radon is a possibility, BC would expect a sealed dpm under the oversite and for it to be linked (sealed) to a dpc in the wall (to form the Radon barrier).

Seems the radon maps oop staffs have been updated and we are seeing a lot more radon faffing at oversite detail.

 

[freddiemercurystwin]

We just have a blanket Radon everywhere assumption down here, given the maps are so vague and it's not much extra to provide the necessary protection.

 

[phatboy]

The oversite can just be some blinding concrete onto the dirt below - it's only there really to keep it 'tidy'.

I'd expect radon protection would be within the floor structure, not the sub floor? The subfloor would usually be ventilated, so radon wouldn't be an issue.

 

[freddiemercurystwin]

The oversite can just be some blinding concrete onto the dirt below - it's only there really to keep it 'tidy'.

I'd expect radon protection would be within the floor structure, not the sub floor? The subfloor would usually be ventilated, so radon wouldn't be an issue.

Not for a suspended floor, radon protection would be beneath the oversite.

 

[^woody^]

Suggesting a radon barrier without all the other associated precautions seems a bit odd.

And if any impermeable barrier is incorporated into the oversite layer, there should be a method for it to drain so that the sub floor void does not hold water.

 

[freddiemercurystwin]

Basic radon protection is as described above, a continuous gas membrane no more. So that can be achieved with a dpm that laps up the inner skin say by one course and then continues into the outer skin lower down, there's no danger of any water from the ground or rain through the wall entering the void. Anyway if the OP lives in a Radon free area it's a non issue but it might be worth the OP checking with their BCO.

 

[Glenn83]

The Radon search for my area shows a maximum of 1-3% Ill check with BCO when the time comes