Do I have a warm or a cold roof?

[bsr]

Hello

From these pictures, can you suggest whether I am likely to have a warm or a cold roof? I am wondering how best to insulate.

The felt upstand is 8cm deep and the fascia 20cm.

Thanks

bsr

 

[bobasd]

from what i can see its a warm roof.
how come you dont know what kind of roof youve got?

 

[^woody^]

You have a roof.

There are two ways to insulate.

1. Remove the felt
2. Remove the ceiling

 

[Notch7]

if you have no soffit or fascia vents, it is either a warm roof or a cold roof done wrongly.

 

[bsr]

Thanks. It sounds like there is no definitive way to tell, other than to make a hole in the ceiling. I'll do that.

My thought is that if there is insulation between the joists it'll be a cold roof. I can measure the depth of the roof and a cold roof would be 25mm or so (OSB + felt) whereas a warm roof would be thicker.

I am doing this because it is a cold room. I have a number of areas to insulate in the house and want to prioritise them.

 

[bsr]

If I want to insulate between the joists, do I need a condensation risk analysis and how do I go about getting one done?

 

[^woody^]

If I want to insulate between the joists, do I need a condensation risk analysis and how do I go about getting one done?

I think you been internetting too much. Just insulate it.

 

[Notch7]

Thanks. It sounds like there is no definitive way to tell, other than to make a hole in the ceiling. I'll do that.

My thought is that if there is insulation between the joists it'll be a cold roof. I can measure the depth of the roof and a cold roof would be 25mm or so (OSB + felt) whereas a warm roof would be thicker.

I am doing this because it is a cold room. I have a number of areas to insulate in the house and want to prioritise them.

A cold roof has a void under the top deck, that void must be ventilated. Then there will be insulation, then vapour barrier.

If its an old roof, it might just be ceiling joists with firrings over and deck on top. There could be rockwall or glass fibre in between the joists.

There may be ceiling joists with firrings pinned in line-in which case you could cut celetex in between pushed up to deck.

Use a vapour barrier and / or foil backed plasterboard

 

[^woody^]

Jeez. It's been there over half a century and is on its second lot of felt at best. There was no concept of warm or cold roof at that time and it does not matter a jot now.

But if it matters it is not deep enough for a warm roof and not ventilated enough for a cold roof. It's a roof. Take the plasterboard down, insulate it, put the plasterboard back up. No need for a two page thread.