Something I've been searching for a lot for my construction is vapor resistance for various common materials. For vapor barriers and underlay fabrics and such that are intended to be used in diffusion-open constructions, it is usually specified very clearly, but for a wall or a roof, combinations of many other materials are also used on different sides of the insulation. I've given up trying to find a complete table of all common materials (has anyone else succeeded?), and now I think the next best thing would be to have the materials ranked by vapor resistance.
Perhaps we can help each other arrange these by increasing vapor resistance? I think it could be valuable for many. I'll make an attempt here, but there are many guesses:
Wind barrier (e.g., Windy)
Exterior gypsum board 9 mm
Gypsum board 13 mm
Building paper
Raw wood paneling 20 mm
Wallpaper + wallpaper paste
Paint (indoor latex paint)
OSB 11 mm
Hardboard (masonite, 3 mm)
Construction plywood (12 mm)
Floor chipboard 22 mm
Oil-tempered hardboard (3 mm)
Vapor retarder (e.g., Halotex)
Vapor barrier (age-resistant plastic)
Perhaps we can help each other arrange these by increasing vapor resistance? I think it could be valuable for many. I'll make an attempt here, but there are many guesses:
Wind barrier (e.g., Windy)
Exterior gypsum board 9 mm
Gypsum board 13 mm
Building paper
Raw wood paneling 20 mm
Wallpaper + wallpaper paste
Paint (indoor latex paint)
OSB 11 mm
Hardboard (masonite, 3 mm)
Construction plywood (12 mm)
Floor chipboard 22 mm
Oil-tempered hardboard (3 mm)
Vapor retarder (e.g., Halotex)
Vapor barrier (age-resistant plastic)
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it can be useful to also write the theoretical value
Great idea!
My old handbook "Bygg", Volume II from the 1960s includes a table with physical data for building materials. For some of the materials, there is information on the "moisture diffusion value" expressed in g/m*h*mm Hg, which can be used to rank the materials. For is valued at 0.0005-0.001, while, for example, fur plywood has a value of 0.005-0.010. The lower the value, the greater the vapor resistance. If you apply these values to your table, sheet material should be higher up and solid wood lower down. Regardless of this information, I can say that latex paint should be almost at the bottom. It is almost completely diffusion-tight.
My old handbook "Bygg", Volume II from the 1960s includes a table with physical data for building materials. For some of the materials, there is information on the "moisture diffusion value" expressed in g/m*h*mm Hg, which can be used to rank the materials. For is valued at 0.0005-0.001, while, for example, fur plywood has a value of 0.005-0.010. The lower the value, the greater the vapor resistance. If you apply these values to your table, sheet material should be higher up and solid wood lower down. Regardless of this information, I can say that latex paint should be almost at the bottom. It is almost completely diffusion-tight.
Thank you for the values. It's confusing that pine plywood is less vapor resistant than solid pine. The glue should reasonably make it more vapor resistant. I also found a table that supports what you write.
Regarding Latex paint, it is probably difficult to place. There seem to be several different types that are more or less diffusion-open and are also affected by surrounding humidity and temperature.
Regarding Latex paint, it is probably difficult to place. There seem to be several different types that are more or less diffusion-open and are also affected by surrounding humidity and temperature.
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There is some merit in only ranking the materials. The data available for vapor resistance of different materials is likely theoretical, derived in a lab environment, perhaps according to a certain standard. In practice, it differs due to varying humidity. The worst possible conditions are a few degrees above freezing, fog, and rain. In other words, typical November weather. How well does a facade board with an SD of 0.3 breathe/dry/move moisture under these conditions?
Example
I got a tip from a salesperson at a major insulation system supplier to only use OSB as a vapor barrier. SD = 2.5. The insulation + facade board (Steico, Pavatex among others) has an SD of 0.55. A factor of 4.5 then. In theory. But perhaps as little as 2-3 in classic, coastal, November weather.
OSB as a vapor barrier certainly works inland, but only probably in coastal areas. That "probably" makes me decide to use vapor barrier foil.
Example
I got a tip from a salesperson at a major insulation system supplier to only use OSB as a vapor barrier. SD = 2.5. The insulation + facade board (Steico, Pavatex among others) has an SD of 0.55. A factor of 4.5 then. In theory. But perhaps as little as 2-3 in classic, coastal, November weather.
OSB as a vapor barrier certainly works inland, but only probably in coastal areas. That "probably" makes me decide to use vapor barrier foil.