Crown roof - warm or cold better?

[JimExtension]

Hello, We’re figuring out the design for our crown roof - something like the attached image, where we have a flat part on the top (with appropriate fall to stop water pooling), and then it would be pitched on three sides.

Would this kind of roof be better as a cold roof or warm roof?
I understand warm roofs are often simpler to construct, but I’m not sure whether the flat to pitched sections would create a problem there?

Thank you

 

[noseall]

Hello, We’re figuring out the design for our crown roof - something like the attached image, where we have a flat part on the top (with appropriate fall to stop water pooling), and then it would be pitched on three sides.

Would this kind of roof be better as a cold roof or warm roof?
I understand warm roofs are often simpler to construct, but I’m not sure whether the flat to pitched sections would create a problem there?

Thank you

Warm every time.
We did one similar a couple of years back, had to have a cranked beam and loads of steel...

lan4.jpg

• noseall
• 27 Mar 2023

crank1.jpg

• noseall
• 22 Dec 2022

 

[JimExtension]

@noseall thanks for the info and photos
Is it a warm roof on the pitched part as well?
I see the insulation on the flat part is below the level of the rafters. Did you then get insulation boards over the top of those rafters?
Thanks!

 

[noseall]

@noseall thanks for the info and photos
Is it a warm roof on the pitched part as well?
I see the insulation on the flat part is below the level of the rafters. Did you then get insulation boards over the top of those rafters?
Thanks!

The vaulted bit is standard cold detail, as this bit is easy to vent. The flattie is warm deck.
The vaulted bit has 75mm PIR between with 75mm across (below) and an air gap above.
The flattie consists of 11.5 mm OSB, 2x 75mm PIR layers with staggered joints and another layer of 11.5mm OSB on top.