Anyone went for a cold flat roof for extension ?

[mothergooseinnorthwest]

Our designer is suggesting cold roof as well as one of the builders we talked to. Mainly because we can have the same ceiling height all though the old and new part.

I read online it doesn’t perform as well on cold winter days and I hate house being cold. There is also possible condensation issues.

Anyway, I’d like to hear from people who have cold roof or had cold roof or have good knowledge about this. Is a cold roof worth considering?

Thanks

I’m watching this thread as well. Similar situation. But we are putting under floor heating all across the extension area. Hence thinking. Warm roof is more budget wise as well.

I’m not entirely sure as to why the cold vs warm roof would impact the internal ceiling height. Unless it’s more to do with an external Planning height restriction?

Nothing wrong with cold flat roofs whatsoever. The main difference between the two is ventilation, which isn’t required for a warm roof. Having a cold roof and rooflights can be a ball ache in relation to the ventilation requirements around the rooflight, etc... I’d always opt for a warm flat roof at single or two storey level and then cold roofs for dormers.

My architect said most of his clients who opted for cold flat roofs had eventual condensation and damp issues, even with ventilation. Part of the issue is the cold roofing but part of it is because flat roofs are more prone to it anyway. We’re having a glazed pitched roof - can you not do that instead to maintain as much ceiling height as possible?

I would never ever agree to have a flat roof. They always have issues eventually. Pitched is always better..

@mothergooseinnorthwest

Our designer is suggesting cold roof as well as one of the builders we talked to. Mainly because we can have the same ceiling height all though the old and new part.

I read online it doesn’t perform as well on cold winter days and I hate house being cold. There is also possible condensation issues.

Anyway, I’d like to hear from people who have cold roof or had cold roof or have good knowledge about this. Is a cold roof worth considering?

Thanks

We've been thinking of using our utility room at the back of our garage as a gym, but the flat roof has no insulation - well come to that neither do the breeze block walls! So you post interested me. I'm not sure what our answer is - probably retro-fitting the roof as a 'proper' cold flat roof, but... Anyway there's a load of Youtube video by this guy from London Flat Roofing and he describes and compares types of flat roof insulation - I drifted off after about 5 minutes of him, but I'm sure the info will help you somewhat! :D

Hmm. Difficult to insulate a flat roof then. Just gives other problems. A single skin breeze block built room isn’t a habitable space. It needs an outer skin to support a decent roof anyway. Double thickness blocks can be insulated. Then a proper roof built on top.

I think your less likely to have issues with the warm roof ( condensation/ airflow/ ventilation) but generally warm roofs are a lot higher than a cold one.