ᐅ Shed roof insulation

Hello everyone,

we are currently looking for a general contractor and have two in our shortlist.
I would like to know which of the roof options is better?

One offer includes
a wooden beam ceiling with wood boarding – insulation between rafters plus 40 mm (1.6 inches) of under-rafter compressible insulation mat.

The other
roof structure with insulation between rafters plus 25 mm (1 inch) Pavatex boards.

Are there any differences?

Thank you very much for your help
Markus

Hi Markus, from an insulation perspective, the second option is preferable because it has a very vapor-permeable construction. Structurally, the first option is stronger since the wooden cladding provides bracing.

The question is, what is actually needed...?

Best regards

Susanne Junghans

Hello Susanne,

Thank you for your feedback.
As a layperson, insulation is the most important aspect for me, since I assume the structural integrity must be ensured ;-)
However, I am very interested in both thermal and acoustic insulation.

I have received some additional information regarding these two points.

One offer includes
wood beam ceiling with wood sheathing – insulation between rafters plus 40mm (1.6 inches) compressed insulation below rafters
– Kalzip roof

The other includes
roof structure with insulation between rafters plus 25mm (1 inch) Pavatex boards
– roof covering (trapezoidal metal sheets)
– battens
– counter battens
– Pavatex wood fiber underlay board, approx. 25mm (1 inch)
– 200mm (8 inches) insulation between rafters (compressed insulation)
– vapor barrier and airtight membrane
– battens
– interior cladding

Could you possibly let me know if these options are also optimal from a thermal and acoustic perspective for a mono-pitched roof? Or what could be improved (for example, thicker Pavatex)?

Thank you very much for your help.
Markus

Hi Markus, the second assembly is correct and works as described. A small note: the Pavatex (25mm (1 inch)) can only be used as an underlay board down to a certain minimum roof pitch. You can call Pavatex to confirm if it’s suitable.

The first assembly doesn’t provide enough details; it might be fine or equivalent, but I can’t tell from the information given. Please provide the exact insulation thickness and the insulation material, and I’ll be happy to comment further.

Best regards

Susanne Junghans