Hello everyone,
Since the construction of the roof frame for my extension is in its final phase, I need to consider insulation and material ordering.
Because this topic is quite complex, I would appreciate your help. It is a 45° (45-degree) pitched roof with a bedroom and an unheated attic. The energy consultant suggested the following setup.
I would like to improve this a bit with a 60mm (2.4 inches) exterior insulation using wood fiber boards for better summer performance.
Since I’m not exactly sure how the ventilation space (counter-batten layer) should be installed and I often read about ventilated insulation, I hope to benefit from your combined knowledge.
The planned layers are:
- Clay roof tiles
- Counter-batten
- Battens
- Underlay membrane
- 60mm (2.4 inches) wood fiber board
- 240mm (9.4 inches) mineral wool insulation
- Vapor barrier / vapor retarder
- 30mm (1.2 inches) mineral wool with battens
- 25mm (1 inch) double-layer drywall
1. Question: Is a true vapor barrier really necessary between the layers of mineral wool?
2. Question: Which type of vapor retarder or barrier should be used (which specifications or values)?
3. Question: Which kind of mineral wool insulation is best (which specifications or values)?
4. Question: Is the construction setup correct as planned, or can it be improved?
Thank you very much for your help. I’m looking forward to lots of input.
Since the construction of the roof frame for my extension is in its final phase, I need to consider insulation and material ordering.
Because this topic is quite complex, I would appreciate your help. It is a 45° (45-degree) pitched roof with a bedroom and an unheated attic. The energy consultant suggested the following setup.
I would like to improve this a bit with a 60mm (2.4 inches) exterior insulation using wood fiber boards for better summer performance.
Since I’m not exactly sure how the ventilation space (counter-batten layer) should be installed and I often read about ventilated insulation, I hope to benefit from your combined knowledge.
The planned layers are:
- Clay roof tiles
- Counter-batten
- Battens
- Underlay membrane
- 60mm (2.4 inches) wood fiber board
- 240mm (9.4 inches) mineral wool insulation
- Vapor barrier / vapor retarder
- 30mm (1.2 inches) mineral wool with battens
- 25mm (1 inch) double-layer drywall
1. Question: Is a true vapor barrier really necessary between the layers of mineral wool?
2. Question: Which type of vapor retarder or barrier should be used (which specifications or values)?
3. Question: Which kind of mineral wool insulation is best (which specifications or values)?
4. Question: Is the construction setup correct as planned, or can it be improved?
Thank you very much for your help. I’m looking forward to lots of input.
In der Ruine20 Sep 2023 14:54parcus schrieb:
Instead of the effort involved in installing exterior roof insulation, you could simply double the rafters by 6cm (2.4 inches).
A 30cm (12 inches) mineral wool insulation with a thermal conductivity of 0.035 W/(m·K) is more than sufficient and may also be eligible for funding under the BEG (BAFA) program.
The mineral wool can also ventilate properly over the counter-battening. Therefore, the 3cm (1.2 inches) interior insulation is not necessary, which also means nothing rests on the possibly damp side of the vapor retarder. That is not really an option. The exterior roof insulation with wood fiber is intended to improve protection against heat.
In der Ruine20 Sep 2023 15:03And the the insulation between the rafters is located beneath the underlay membrane.