Perm ratings for ceramic and porcelain tiles

[Michael Hurd]

I've been trying to track down information on the perm ratings for ceramic and porcelain tiles, anyone have a general range or any information at all? I'm trying to run a wall that in certain rooms has a shower against the exterior wall.

[Thomas]

Hi Michael,

WUFI's drop-down list for sd-values at the surfaces suggests sd = 2 m for tiles, but I'm not sure where precisely this number comes from.

Glazed tiles will be virtually impermeable to vapor, so the vapor exchange will almost exclusively happen through the "joints" (what's the word?) between the tiles. The overall perm rating for the wall surface will then be determined by the diffusion properties of the "mortar" between the tiles and the fractional surface area covered by the mortar joints. I suspect that this is what the 2 m quoted above refer to.

Kind regards,
Thomas

[Michael Hurd]

Thanks Thomas. In addition, when I think about this more clearly, for the condition I have, there will be a waterproofing behind the tiles that is virtually impermeable also, so the tile and its joints are really not a factor in my mind.