concrete floor insulation

[Grandad Gaz]

Hi, after a bit of advice from those in the know.

We are currently building an extension where 100mm of celotex has been specced under the floor screed (and on top of the concrete sub base)

Is there an alternative which would give me the same U value, but is a bit thinner. i.e: 75mm or less and still satisfy BC?

Reason being, I need all the head height I can get!

Cheers

[henrycrun]

Just dig deeper ? Sorry but don't understand

[Toilet Duck]

Can't you make the ceiling higher then it won't matter about the floor depth? P.S. there is no charge for this professional advice.

[andye30m3]

I thought 75mm celotex on top of the concreate floor is sufficient to achieve the u-values for building control for an extension.

[GuinnessMK]

andye30m3 said:

I thought 75mm celotex on top of the concreate floor is sufficient to achieve the u-values for building control for an extension.

It's not just a straight depth, there is a function of the perimeter to area ratio that needs to be taken into account.

As said, can you not dig down a bit further?

[andye30m3]

GuinnessMK said:

andye30m3 said:

I thought 75mm celotex on top of the concreate floor is sufficient to achieve the u-values for building control for an extension.

It's not just a straight depth, there is a function of the perimeter to area ratio that needs to be taken into account.

As said, can you not dig down a bit further?

Thats right, I used the celotex website to spec the insulation and that takes into account the perimeter to area ratio.

[Grandad Gaz]

andye30m3 said:

GuinnessMK said:

andye30m3 said:

I thought 75mm celotex on top of the concreate floor is sufficient to achieve the u-values for building control for an extension.

It's not just a straight depth, there is a function of the perimeter to area ratio that needs to be taken into account.

As said, can you not dig down a bit further?

Thats right, I used the celotex website to spec the insulation and that takes into account the perimeter to area ratio.

Thanks. I'll see what I can find out.

As for digging down further. Not possible, Concrete sub base is already done