ᐅ Timber Frame Construction – Moisture Issues from Airtight Layers?
Created on: 7 Mar 2020 22:17
M
MMarple
Hello everyone,
I hope this is the right section for my concern.
Here is the situation: At the end of October, we started having a two-story extension built on top of our garage by a professional company. The extension was constructed using a timber frame method.
We were advised to apply a bitumen layer on the flat roof of the garage due to the risk of rising moisture (when a wet car is parked inside). We followed this recommendation.
The extension was then built on the garage / the timber was laid. Insulation material was placed in the gaps between the structural timber. A membrane (airtight and waterproof) was installed on top, followed by OSB boards.
By chance (we needed an opening to the garage for the heating system installations), we discovered that water was actually standing in this cavity (between the garage roof and the ground floor ceiling)! It can be ruled out that the water entered from the outside.
We were told that the issue is caused by the airtight and waterproof sealing on both sides. The residual moisture in the wood can no longer escape.
We have now removed the OSB boards and the membrane, and there is indeed a significant amount of water standing in the ground floor ceiling space.
My question: Is it possible that that much moisture can still come from kiln-dried structural solid wood? Or does this suggest that "wet" wood was used (a defect)?
And is it sufficient, after initial drying/ventilation, to reinstall the OSB boards with ventilation holes (and this time using a vapor-permeable membrane)? I am concerned that this will not provide enough ventilation—especially since a vinyl floor is planned as the final finish on the ground floor ceiling.
Thank you very much in advance for your answers!
I hope this is the right section for my concern.
Here is the situation: At the end of October, we started having a two-story extension built on top of our garage by a professional company. The extension was constructed using a timber frame method.
We were advised to apply a bitumen layer on the flat roof of the garage due to the risk of rising moisture (when a wet car is parked inside). We followed this recommendation.
The extension was then built on the garage / the timber was laid. Insulation material was placed in the gaps between the structural timber. A membrane (airtight and waterproof) was installed on top, followed by OSB boards.
By chance (we needed an opening to the garage for the heating system installations), we discovered that water was actually standing in this cavity (between the garage roof and the ground floor ceiling)! It can be ruled out that the water entered from the outside.
We were told that the issue is caused by the airtight and waterproof sealing on both sides. The residual moisture in the wood can no longer escape.
We have now removed the OSB boards and the membrane, and there is indeed a significant amount of water standing in the ground floor ceiling space.
My question: Is it possible that that much moisture can still come from kiln-dried structural solid wood? Or does this suggest that "wet" wood was used (a defect)?
And is it sufficient, after initial drying/ventilation, to reinstall the OSB boards with ventilation holes (and this time using a vapor-permeable membrane)? I am concerned that this will not provide enough ventilation—especially since a vinyl floor is planned as the final finish on the ground floor ceiling.
Thank you very much in advance for your answers!
Vicky Pedia9 Mar 2020 23:56The photo unfortunately doesn’t reveal much. I suspect condensation caused by the double layer of foil. Let it dry out and leave the foil only on the north side, allowing the bottom to “breathe.” It’s quite difficult with so little information...
Could you tell me the federal state?
Could you tell me the federal state?
H
hampshire10 Mar 2020 15:19My rough estimate from post #4 is highly theoretical and only holds true if the surrounding environment of the wood is exceptionally dry and simultaneously unable to absorb water from the air. This is very theoretical and a convenient excuse. The moisture definitely does not come from the wood.
If it did, I would immediately adopt this method for firewood drying.
Don’t let yourself be brushed off.
If it did, I would immediately adopt this method for firewood drying.
Don’t let yourself be brushed off.
It is completely impossible for the KVH to emit that much water vapor.
MMarple schrieb:Often the simplest explanation is the best, even if it is generally excluded.
The possibility that the water penetrated from the outside is ruled out.
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