Roofing Question

Replacing flat roof. does it need insulation according to building regs?

I have a house with pitched roof but three other elevations (e.g extension) which are flat roof. One large flat roof was replaced with EPDM January 2017 but no roof insulation was installed.
I need to replace another elevation and not sure if that needs insulation. Looking at the current building regs, if more than 25% of a roof is replaced then it need to be thermally upgraded.
In the case of my mixed roof house, does replacing a flat roof elevation constitute a 100% replacement, or would it be as a percentage of the total roof on the house?

Do you think the the roofer in 2017 should have put insulation in according to the building regulations?

3 Answers

Best Answer

If you are replacing more than 25% of one roof (not combined totals) then it should be converted to a warm roof. The actual benefits of a warm roof are very advantageous even in summer (when the room will stay cooler). I would recommend it but it does hit the old piggy bank because you generally have to replace your fascia with a deeper profile - and to fully conform you need 120mm of solid insulation.

With a warm roof the rooms below are more efficient and warm up really quick when the heating comes on - it is worth it....


Drew @ Fibretechs

Answered 4th Nov 2018


Member since 26 Jul 2012

My understanding of the regs is yes it does require insulating if not up to standard and also notification and signing off by building control or competent person. However this seems to be the most widely ignored rule out there by both roofers, customers and local councils.

Answered 19th Nov 2018

The Affordable Roofing Company Ltd

Member since 20 Jan 2015

It`s always better to fit a warm roof to a flat roof. As the building control officers all have different interpretations of the regs, I always give a price for both options. Insulation,though more costly will always pay back in the long run. I asked a client to check this week with building control and they told him he did`nt need to insulate! Ring them next week and you will probably get a different answer. Hope that helps...

Answered 4th Nov 2018

S Nash Roofing

Member since 1 Aug 2008

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