Higher Standards for Exceptional Installations

Most of you have already seen the new TCNA Handbook for Ceramic Tile Installation 2011. One newly revised application instructs installers on how to build safer and more sustainable steam rooms.

This includes creating a strong vapor barrier to keep water vapor from penetrating through your wall installation into the substrate, which can cause damage due to condensation. The hot temperature (ca 110ºF) and resulting high air pressure will force the vapor-saturated air on the inside of the steam room to attack the wall behind which there is a much cooler lower pressure environment. Because the inside environment is then forced to equalize the differential imbalance which can only occur if air and vapor can penetrate the wall and reach the other side. This inevitably causes damage. Therefore, we must contain the air and vapor flow and build up a barrier on the inside, the warm side, of the steam room. This barrier must be strong enough to retard water and water vapor. (See illustration.)

Although the TCNA added numerous precautionary sections making clear that a suitable membrane and installation system must be used to prevent moisture migration, it will remain impossible for installers and designers to determine the vapor retarding strength of their systems so long as many manufacturers of waterproof membranes (liquid or sheet applied) do not test and/ or publish their capabilities. The strength of a vapor retarder is measured in PERMS (permeability of a material). It was common industry standard to qualify any waterproof membranes tested with a result of 1 PERM or less as a sufficient vapor retarder. Many waterproofing membranes do not pass this test. For example, a PERM rating can be as high as 5 PERMS while still passing regular waterproofing tests such as ANSI 118.10-1999

To read more, download the entire pdf here!