Good evening,
The screed is currently drying in the new building.
The following question came up today:
I would like to insulate the roof structure, and the rafter thickness is 20cm (8 inches).
I am considering using mineral wool insulation, but what thickness should I install?
18cm (7 inches) to allow some air circulation, 20cm (8 inches), or 22cm (9 inches) (the thicker, the denser it becomes).
After installing the insulation, I plan to place the vapor barrier on top, then install counter battens on the outside, and finally fix drywall over that.
Thank you
The screed is currently drying in the new building.
The following question came up today:
I would like to insulate the roof structure, and the rafter thickness is 20cm (8 inches).
I am considering using mineral wool insulation, but what thickness should I install?
18cm (7 inches) to allow some air circulation, 20cm (8 inches), or 22cm (9 inches) (the thicker, the denser it becomes).
After installing the insulation, I plan to place the vapor barrier on top, then install counter battens on the outside, and finally fix drywall over that.
Thank you
The required thickness of the insulation depends on the thermal conductivity class (WLG) of the insulation material and the insulation thickness calculated in the thermal protection calculation. Together with the rest of the building component assembly, this must result in a thermal transmittance coefficient (U-value) that meets the requirements of the energy-saving regulation: 0.24 W/m²K, or 0.14 W/m²K for individual measures eligible for KfW funding.
The remaining questions can only be answered in connection with the building materials already installed and if the basic structure of the roof assembly is known. In any case, the ventilation layer in a new build is not installed between the insulation and the underlay/roof deck, but rather above the underlay/roof deck, in the counter-batten layer and outside of the insulated roof.
If your planning documents do not provide clear information on this, you should seek professional and independent advice—and by that, I do not mean the home improvement store. It is better not to act at all than to act incorrectly.
The remaining questions can only be answered in connection with the building materials already installed and if the basic structure of the roof assembly is known. In any case, the ventilation layer in a new build is not installed between the insulation and the underlay/roof deck, but rather above the underlay/roof deck, in the counter-batten layer and outside of the insulated roof.
If your planning documents do not provide clear information on this, you should seek professional and independent advice—and by that, I do not mean the home improvement store. It is better not to act at all than to act incorrectly.
R
readytorumble9 Dec 2017 15:22Under no circumstances should it be thicker than 20cm (8 inches) for a rafter depth of 20cm (8 inches). The mineral wool should not be compressed, as the air trapped inside provides insulation.
You should check your thermal insulation certificate. It specifies the minimum values that must be met. The person who calculated this certificate is also responsible for the correct execution. So who was that in your case?
You should check your thermal insulation certificate. It specifies the minimum values that must be met. The person who calculated this certificate is also responsible for the correct execution. So who was that in your case?
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