Hello everyone,
I am new to this forum.
I recently bought an old timber-framed house (built in 1920). The roof was renovated about 5 years ago but was not insulated.
Now I want to properly insulate the roof. It won’t be used as living space, as it’s too small for that after insulation.
I have some questions about this:
- The first layer of Homatherm Holzflex 100mm (4 inches) will be fitted between the existing rafters.
- I want to apply the second layer (the exact same product) directly on top, using double-sided tape on the lower layer or the rafters, but without doubling up the rafters (either lengthwise or crosswise) because that would create more thermal bridges.
However, this causes a problem with properly fixing the final OSB-3 board, 18mm (0.7 inches) thick.
I could either screw wooden blocks measuring 100 x 100 x 100mm (4 x 4 x 4 inches) onto the existing rafters at certain points and attach the boards to those, or use long screws going through the 100mm (4 inches) Homatherm mats (which would probably cause significant thermal bridging).
Has anyone faced this problem before?
I would really appreciate any tips or tricks.
Thank you very much,
Nick
I am new to this forum.
I recently bought an old timber-framed house (built in 1920). The roof was renovated about 5 years ago but was not insulated.
Now I want to properly insulate the roof. It won’t be used as living space, as it’s too small for that after insulation.
I have some questions about this:
- The first layer of Homatherm Holzflex 100mm (4 inches) will be fitted between the existing rafters.
- I want to apply the second layer (the exact same product) directly on top, using double-sided tape on the lower layer or the rafters, but without doubling up the rafters (either lengthwise or crosswise) because that would create more thermal bridges.
However, this causes a problem with properly fixing the final OSB-3 board, 18mm (0.7 inches) thick.
I could either screw wooden blocks measuring 100 x 100 x 100mm (4 x 4 x 4 inches) onto the existing rafters at certain points and attach the boards to those, or use long screws going through the 100mm (4 inches) Homatherm mats (which would probably cause significant thermal bridging).
Has anyone faced this problem before?
I would really appreciate any tips or tricks.
Thank you very much,
Nick
J
jupartner12 Jul 2015 15:36Hi Nick,
You’re definitely on the right track with running insulation both lengthwise and crosswise to address thermal bridges.
A professional would actually screw a 100mm (4 inch) squared timber crosswise onto the rafters because wood fiber insulation is a soft mat that needs a support structure. This makes the whole setup much more stable and also provides a solid base for your interior cladding.
Alternatively, there are also rigid, dimensionally stable wood fiber boards with the same insulation value (040) – I’m not sure about Homatherm, but the three major brands (Gutex, Pavatex, Steico) offer these. You can use them as 100mm (4 inch) insulation below the rafters as well. They come in 2.50m (8.2 feet) lengths, with tongue and groove or shiplap edges, and are installed perpendicular to the rafters (you place one board on top of another and they interlock). Get advice from a timber wholesaler; they will have the right screws for this (I’d guess 160mm or 180mm (6.3 inch or 7 inch)), not the small screws you usually find at hardware stores.
Then you install the vapor barrier directly afterward (don’t forget!) – or you can use OSB boards.
Good luck with your work
Susanne Junghans
You’re definitely on the right track with running insulation both lengthwise and crosswise to address thermal bridges.
A professional would actually screw a 100mm (4 inch) squared timber crosswise onto the rafters because wood fiber insulation is a soft mat that needs a support structure. This makes the whole setup much more stable and also provides a solid base for your interior cladding.
Alternatively, there are also rigid, dimensionally stable wood fiber boards with the same insulation value (040) – I’m not sure about Homatherm, but the three major brands (Gutex, Pavatex, Steico) offer these. You can use them as 100mm (4 inch) insulation below the rafters as well. They come in 2.50m (8.2 feet) lengths, with tongue and groove or shiplap edges, and are installed perpendicular to the rafters (you place one board on top of another and they interlock). Get advice from a timber wholesaler; they will have the right screws for this (I’d guess 160mm or 180mm (6.3 inch or 7 inch)), not the small screws you usually find at hardware stores.
Then you install the vapor barrier directly afterward (don’t forget!) – or you can use OSB boards.
Good luck with your work
Susanne Junghans
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