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handwerk9725 Aug 2024 14:53Hello everyone from Bavaria,
I am about to insulate our attic.
The reason for this is heating costs as well as heat during the summer.
The attic will not be converted into living space.
My problem is that the roof is quite new. So, a new roof with exterior insulation under the tiles is not an option.
Basically, it consists of rafters, boards, roofing felt, and then tiles.
The rafters are only 12cm (5 inches) thick. Adding extra layers is possible but not desired.
The top floor ceiling consists of a layer of boards and an 18cm (7 inches) cavity. There is very old glass wool insulation visible, which is partially only half-installed or has collapsed. I have already found a professional company for disposal.
What are your thoughts?
I would like to replace the old glass wool on the top floor ceiling with 180mm or 200mm (7 or 8 inches) wood fiber insulation and lay a vapor retarder over the joists beforehand. Above that, I would like to install OSB boards, but that would then be vapor-tight.
For the rafters, I was thinking of installing Pavatex boards on the inside (with a counter batten to create an air gap to the boards).
What would be the best solution?
I am about to insulate our attic.
The reason for this is heating costs as well as heat during the summer.
The attic will not be converted into living space.
My problem is that the roof is quite new. So, a new roof with exterior insulation under the tiles is not an option.
Basically, it consists of rafters, boards, roofing felt, and then tiles.
The rafters are only 12cm (5 inches) thick. Adding extra layers is possible but not desired.
The top floor ceiling consists of a layer of boards and an 18cm (7 inches) cavity. There is very old glass wool insulation visible, which is partially only half-installed or has collapsed. I have already found a professional company for disposal.
What are your thoughts?
I would like to replace the old glass wool on the top floor ceiling with 180mm or 200mm (7 or 8 inches) wood fiber insulation and lay a vapor retarder over the joists beforehand. Above that, I would like to install OSB boards, but that would then be vapor-tight.
For the rafters, I was thinking of installing Pavatex boards on the inside (with a counter batten to create an air gap to the boards).
What would be the best solution?
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nordanney25 Aug 2024 15:10Simplified from bottom to top: vapor barrier (tight enough to prevent moisture from the upper floor entering the insulation), insulation, OSB boards.
Alternatively, you can simply replace the old insulation and add mineral wool on top. However, the floor will no longer be walkable. In that case, you don’t need a vapor barrier.
Alternatively, you can simply replace the old insulation and add mineral wool on top. However, the floor will no longer be walkable. In that case, you don’t need a vapor barrier.
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handwerk9725 Aug 2024 15:25@nordanney first of all, thanks for the reply.
Installing OSB boards on top is not a problem as long as there is a vapor barrier towards the lower floor. Is there anything to consider here? Does the manufacturer matter?
I also have a big question regarding which building material I should use.
I like wood fiber insulation because it doesn’t compress and is natural, although its insulation value is lower.
I don’t want mineral wool. The space is supposed to be walkable and used for storage. That’s why OSB boards, since I don’t like the other options.
I have also been told that a vapor retarder is not necessary if you lay boards again that allow air to pass through.
Installing OSB boards on top is not a problem as long as there is a vapor barrier towards the lower floor. Is there anything to consider here? Does the manufacturer matter?
I also have a big question regarding which building material I should use.
I like wood fiber insulation because it doesn’t compress and is natural, although its insulation value is lower.
I don’t want mineral wool. The space is supposed to be walkable and used for storage. That’s why OSB boards, since I don’t like the other options.
I have also been told that a vapor retarder is not necessary if you lay boards again that allow air to pass through.
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