ᐅ Dew Point in Exterior Roof Insulation / Insulation Options
Created on: 23 Sep 2013 16:33
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aus-dem-GebirgeA
aus-dem-Gebirge23 Sep 2013 16:33Hello to all roofing and construction experts,
Here is a description of the building: a heated hall with a long lean-to roof. The current roof covering consists of a single layer of roofing felt and roofing felt shingles. However, water has leaked in—not just locally—so it is assumed that the roof covering is generally leaking or increasingly becoming leaky. Inside, everything is wet. The action taken so far: interior drywall removed along with the vapor barrier and wet insulation, allowing the rafters and sheathing to dry out first.
Winter is approaching, and the idea now is to install continuous insulation above the rafters on the roof. This should preferably be applied directly on top of the old roof covering. On top of that, trapezoidal aluminum sheets will be installed as the new roof covering.
Inside, after drying over the winter, only a visible cladding of the rafters and sheathing is planned.
My question: Do I need to consider anything regarding the dew point in the planning? Should a vapor-permeable (breathable) membrane be installed over the old roof covering before applying the continuous insulation (rigid foam variant, possibly with an OSB board on top)? Or are there recommendations for a different insulation method? How thick should the insulation be? Are there any critical points to watch out for, such as the wall-to-roof transition?
Thank you in advance for your help!
Best regards!
Here is a description of the building: a heated hall with a long lean-to roof. The current roof covering consists of a single layer of roofing felt and roofing felt shingles. However, water has leaked in—not just locally—so it is assumed that the roof covering is generally leaking or increasingly becoming leaky. Inside, everything is wet. The action taken so far: interior drywall removed along with the vapor barrier and wet insulation, allowing the rafters and sheathing to dry out first.
Winter is approaching, and the idea now is to install continuous insulation above the rafters on the roof. This should preferably be applied directly on top of the old roof covering. On top of that, trapezoidal aluminum sheets will be installed as the new roof covering.
Inside, after drying over the winter, only a visible cladding of the rafters and sheathing is planned.
My question: Do I need to consider anything regarding the dew point in the planning? Should a vapor-permeable (breathable) membrane be installed over the old roof covering before applying the continuous insulation (rigid foam variant, possibly with an OSB board on top)? Or are there recommendations for a different insulation method? How thick should the insulation be? Are there any critical points to watch out for, such as the wall-to-roof transition?
Thank you in advance for your help!
Best regards!
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