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Renovator27 Jun 2016 13:56I would like to add insulation to the roof of a single-family house from the 1960s.
The roof structure from inside to outside is as follows:
Gypsum, reed mat, boarding with an air gap, rafters, 60 mm (2.4 inches) mineral wool between the rafters, air, flush boarding, multiple layers of roofing felt.
Since the roof is still watertight, I would prefer not to improve the insulation between the rafters. To do so, the ceiling would have to be opened from the inside and rebuilt afterward, which seems unnecessary. Also, removing the roofing felt and boarding from the outside does not make much sense.
What do you think about applying 100 mm (4 inches) PUR (polyurethane) panels on top of the intact roofing felt from the outside and then sealing them again with roofing felt? I would resheath the edges and pay close attention to thermal bridges.
The roof structure from inside to outside is as follows:
Gypsum, reed mat, boarding with an air gap, rafters, 60 mm (2.4 inches) mineral wool between the rafters, air, flush boarding, multiple layers of roofing felt.
Since the roof is still watertight, I would prefer not to improve the insulation between the rafters. To do so, the ceiling would have to be opened from the inside and rebuilt afterward, which seems unnecessary. Also, removing the roofing felt and boarding from the outside does not make much sense.
What do you think about applying 100 mm (4 inches) PUR (polyurethane) panels on top of the intact roofing felt from the outside and then sealing them again with roofing felt? I would resheath the edges and pay close attention to thermal bridges.
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garfunkel28 Jun 2016 20:55You need to be a bit careful about moisture.
The key terms are vapor-permeable and vapor-tight. Unfortunately, I can’t provide more details here as I’m not an expert.
If you get it wrong, your roof could end up with severe mold problems.
It’s better to get advice from a professional. If you only need guidance and feel confident handling the work yourself, this usually doesn’t cost much to consider.
With PUR boards, you should think about sound insulation in advance. The sound insulation of PUR or rigid foam insulation is minimal to basically none.
It depends on the specific situation (place of residence, busy street in front of the house, etc.).
You still have the interior insulation, which will probably provide sufficient soundproofing, but it would be very frustrating if you ended up using the wrong insulation material for your needs.
The key terms are vapor-permeable and vapor-tight. Unfortunately, I can’t provide more details here as I’m not an expert.
If you get it wrong, your roof could end up with severe mold problems.
It’s better to get advice from a professional. If you only need guidance and feel confident handling the work yourself, this usually doesn’t cost much to consider.
With PUR boards, you should think about sound insulation in advance. The sound insulation of PUR or rigid foam insulation is minimal to basically none.
It depends on the specific situation (place of residence, busy street in front of the house, etc.).
You still have the interior insulation, which will probably provide sufficient soundproofing, but it would be very frustrating if you ended up using the wrong insulation material for your needs.
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