cold or warm flat roof

Simon Man · 23 Sep 2020

Hi there. im looking at getting a flat roof extension and I can see that there are 2 options - warm or cold flat room. Can anyone please tell me if there are many differences between the 2 part from the way they are constructed. Is one better insulated than the other or would one be cheaper to put together than the other?

any advise is apprecated! thanks

Alastairreid · 23 Sep 2020

https://www.jjroofingsupplies.co.uk/blog/warm-roof-vs-cold-roof-whats-the-difference/

Notch7 · 23 Sep 2020

If you want downlighters a warm roof is easier.

If you choose a cold roof you must ensure cross ventilation is satisfactory.

If you explain a bit more about your extension we can advice further

Simon Man · 25 Sep 2020

Notch7

Thanks for the reply. Its a kitchen extension that will be extended to then bring it into an existing dining room to make one large area. Do you mean spot lights when you say downerlights? we would like spot lights. I was also wondering which is better for thermal efficiency, warm or cold? or are they the same

thanks again

Londoner2 · 25 Sep 2020

Warm roof all the way.

Warm roof is a much better way to insulate most of the roof, it will ensure minimum cold bridging and keep warmth in.
Cold roof is more prone to draughts as it needs to be constructed properly.

Simon Man · 25 Sep 2020

thanks for the reply! we are getting skylight / lantern, so would this make a difference to what we would need?

Londoner2 · 25 Sep 2020

Sijames said:
thanks for the reply! we are getting skylight / lantern, so would this make a difference to what we would need?

No, i had my extension done last year, warm roof with a crappy lantern as well, its very common.

If you put in a lantern make sure its supported properly, the bulider told me i don't need beams, I told him i'm gonna put it in as it will avoid deflection after a few years.

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cold or warm flat roof

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