Single storey extension flat roof insulation options

10 replies
Found 21st Oct 2016
During renovating the back of house and extension ive found the extension to have just 100mm rockwool insulation in the flat roof. I just want to explore options when putting new insulation back in to maximise the effectiveness of the insulation.
Joist size = 200mm
Flat Roof
Room size 5.6m x 5.7m
Roof size 5.6m x 1.6m

I was toying with the idea of 75mm Celotex / Kingspan with 100mm rockwool. There are a couple of pipes up there and there will be firerated led spotights being installed also.

Thanks in advance for any suggestions.

10 Comments

we're currently extending our property and as per our architects drawings/planning permission/building regs all insulation has been 170mm thick.

100mm duoslab

I would stick with just the Celotex/Kingspan .

You should fit fire hoods to the spotlights and use low heat builds such as LED

Original Poster

loobyonetwothree

we're currently extending our property and as per our architects … we're currently extending our property and as per our architects drawings/planning permission/building regs all insulation has been 170mm thick.


Cheers. Does regs state thickness or just Rvalue?

off the top of my head it's shown on the architects drawings the actual thickness....building regs haven't put anything in writing that I've seen but ensured we have fulfilled what's been drawn up and agreed by planning/council.

The regs inspector will require a set amount depending on your area etc, best speak to them.

170mm should be OK and leave enough room for air to flow and the odd pipe etc.

Banned

how much do architects charge for planning a extension? I'm thinking of doing the same as I live in a end property

Original Poster

sofiasar

how much do architects charge for planning a extension? I'm thinking of … how much do architects charge for planning a extension? I'm thinking of doing the same as I live in a end property



Ive heard they carge anything between 10-20% of your complete build costs.

Original Poster

markvirgo

The regs inspector will require a set amount depending on your area etc, … The regs inspector will require a set amount depending on your area etc, best speak to them.170mm should be OK and leave enough room for air to flow and the odd pipe etc.


Do you leave the air gap above or below the insulation?

bigweapon07

Do you leave the air gap above or below the insulation?



Air gap should be above, fit it level with the front of the wooden beams.
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