Plain drywall used as tile backer at shower enclosures

[John Onofrey]

IRC 702.4.2 states that, "Gypsum board utilized as the base or or backer board for adhesive application of ceramic tile or other nonabsorbent finish material shall conform with ASTM C630 or C1178."

Anyone know what is in those ASTM standards?

I inspected a home with 4.5 baths and moisture resistant backer board was not used at the tub/shower enclosures.

Do the ASTM standards call for moisture resistant backer in this application?

I understand what common sense dictates but I'm trying to leave common sense out of this for now.

[gbeaumont]

Hi to all,

John,

ASTM C630 relates to the standard of moisture resistant drywall.

ASTM C1178 relates to fiberglass reinforced moisture resistant dry wall.

So yes, the quick answer is that the drywall should be moisture resistant.

Regards

Gerry

[Michael R. Boyett]

If it's important you can buy & immediately download the ASTM standards at http://www.astm.org/cgi-bin/SoftCart...894+1142792261 . It looks like C630 has been superceded by C1396 but, in any case, all of those standards are available for about $30 ea.

[John Onofrey]

Thanks guys.

[Jay Moge]

i don't use anything but M.R. board (or "green board") for tub walls. i alway thought that the moisture in the mastic alone would be step one in the down fall of the plain drywall. never tried it, but then again you said to leave common sence out for now so...........