Warm Roof with bare tiles

[bonobobrown]

Heaving skimmed through a number of posts none seem to quite fit my project.
I have a 1930's roof which has tiles and nothing else - no membrane or felt.
I want to make it a warm roof.
I was planning on putting 50mm celotex or similar between the rafters and then 100mm over the top across the rafters. taping all the seams.

Do I need to include a breathable membrane anywhere in this ?
Is 50mm of airgap between the insulation and the bare tiles enough ?

I am worried that I will create a nice warm roof that will end up a warm but rotting roof with condensation.

 

[freddiemercurystwin]

You should also consider that you would require planning permission to raise the ridge. Also, what advantage do you envisage with such a roof make-up? That's not to say there is anything wrong with a warm pitched roof per se, just curious.

 

[noseall]

Yes, use breathable membrane.

True 'warm roofs' do not require cross ventilation.

You would normally fix the insulation, membrane, then fix counter-battens before fixing the roofing battens thus automatically creating an air gap'

 

[Alastairreid]

Do I need to include a breathable membrane anywhere in this ?

Not unless you plan on retiling your roof.

 

[freddiemercurystwin]

Do I need to include a breathable membrane anywhere in this ?

Not unless you plan on retiling your roof.

How would you construct a warm roof without re-tiling?

 

[Alastairreid]

I want to make it a warm roof.
I was planning on putting 50mm celotex or similar between the rafters and then 100mm over the top across the rafters. taping all the seams.

The way that reads he intends using 100mm as an underdraw ...

 

[bonobobrown]

Thanks all for your comments.

Sorry for the delay in replying - the joys of DIY plus the day job.

So - I am planning on doing this because I have already insulated the floor, but am facing issues storing things in the loft due to slight damp and at the moment very cold.

I don't want to re-roof - so I am rather stuck with the bare tiles, then baton, then rafter construction that is in place.

I have uploaded two images that might make it clearer. I was planning on something like in the second image where I have a thinner section of insulation between the rafters so as to maintain an air-gap behind. Then a thicker sheet over the top.

At the apex I will construct a frame so that the air can flow from one side of the roof to the other with a void left at the top.

The only place I could think of putting a membrane ( if required ) would be between the two sections of insulation.

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• bonobobrown
• 13 Dec 2013
• 1

Untitled

• bonobobrown
• 13 Dec 2013
• 1

[/img]

 

[bonobobrown]

I suppose one additional question would be - am I calling it the correct thing ?
Is it a warm roof that I am trying to achieve or is there another term for this kind of insulating project ?

 

[Alastairreid]

A warm roof is when the insulation is placed above the rafters.

You can increase the depth of the rafters by adding additional straps to the underside, then you can fit the 100mm insulation between then 50mm beneath.

You dont need a breathable membrane anywhere in your set up.

 

[freddiemercurystwin]

I suppose one additional question would be - am I calling it the correct thing ?
Is it a warm roof that I am trying to achieve or is there another term for this kind of insulating project ?

Doh! The ol' terminology problem again!