hans_dampf
2020-01-16 21:32:21
- #1
Hello everyone,
[ATTACH width="559px" type="full"]42022[/ATTACH]
I urgently need help with this ceiling construction (see picture).
Outside: unheated attic, but will be converted in a few years
Inside: living space
According to the above construction, there is 0.22 kg/m2 of condensate. If I now replace the variable climate membrane with a vapor retarder with a high sd-value, the calculation shows no condensate.
According to statements in various forums, however, it is almost impossible that vapor retarders and climate membranes remain airtight for years and that then a large amount of condensate could penetrate the construction by convection. Due to the tight OSB board on top and the tight vapor retarder at the bottom, the water could no longer escape and would cause damage to the construction.
Which option involves fewer risks? The variable climate membrane with low diffusion and drying potential or the vapor retarder and hope that everything remains airtight.
Or are there other possibilities?
Current unchangeable condition of the ceiling:
- 25mm OSB boards
- Beams KVH 220/100
- Glass wool 035 260mm
Best regards
[ATTACH width="559px" type="full"]42022[/ATTACH]
I urgently need help with this ceiling construction (see picture).
Outside: unheated attic, but will be converted in a few years
Inside: living space
According to the above construction, there is 0.22 kg/m2 of condensate. If I now replace the variable climate membrane with a vapor retarder with a high sd-value, the calculation shows no condensate.
According to statements in various forums, however, it is almost impossible that vapor retarders and climate membranes remain airtight for years and that then a large amount of condensate could penetrate the construction by convection. Due to the tight OSB board on top and the tight vapor retarder at the bottom, the water could no longer escape and would cause damage to the construction.
Which option involves fewer risks? The variable climate membrane with low diffusion and drying potential or the vapor retarder and hope that everything remains airtight.
Or are there other possibilities?
Current unchangeable condition of the ceiling:
- 25mm OSB boards
- Beams KVH 220/100
- Glass wool 035 260mm
Best regards