Hello,
It is possible to determine the good value Sd of adorn vapor of a wall with the software WUFI. In France the DTU 31.2 for the constructions wood asks for a value Sd superior or equal to 18 m.
Sd Value for a Wall
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chouchen29
- WUFI User
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Sd Value for a Wall
chouchen29
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Amandine Piot
- WUFI International Support Team
- Posts: 40
- Joined: Mon Feb 28, 2011 11:02 pm -1100
Hello,
You can adjust this value in the material properties dialog (double click on the material, then "unlock" it by clicking on the lock picture, you can then edit your material). The vapour barrier must always have a thickness of 1mm, or that can create numerical problems. You must therefore adjust the mu value ("résistance à la diffusion de vapeur") in order to have a Sd of 18m:
You can adjust this value in the material properties dialog (double click on the material, then "unlock" it by clicking on the lock picture, you can then edit your material). The vapour barrier must always have a thickness of 1mm, or that can create numerical problems. You must therefore adjust the mu value ("résistance à la diffusion de vapeur") in order to have a Sd of 18m:
- Sd=mu*thickness => mu=18m/0,001m=18000