Licensed Termite Inspectors are required to water test stall showers during a routine inspection as mandated by California State Law. The test requires filling the base of the shower with water to within one inch of the top of the dam (section 1991(a)12 of the California Code of Regulations). The intention is to disclose faulty waterproofing during the termite inspection. Stall showers over a finished ceiling (2nd story) are not water tested, but are visually inspected for signs of leakage from below. One Home Inspector I have spoken to stated that "Standing water in the base of a shower exceeds normal use." Most Home Inspectors do not water test shower pans and defer that determination to the Termite Inspector as it is within the scope of their required inspection process. A standard "Flood Test" during a termite inspection looks something like this;

A typical stall shower is constructed of tile and concrete with a layer of waterproofing below. General shower construction code can be found in section 411 of the California Uniform Building Code. If not constructed properly, leakage may occur and cause significant water damage and lead to wood rot or other wood destroying pests. Building Inspectors test shower pans before the installation of mortar and tile. The building test code looks like this;

The test listed in section 1991(a)12 of the California Code of Regulations has been in place for over the 30 years I can remember and most likely since the beginning of the Structural Pest Control Board in 1950. I speculate that the current Termite Inspection shower test was intended to duplicate the building code test in a "Post Construction" condition and bring the water level to the level of the "rough threshold" with waterproofing. The following pictures shows how the test is intended to work with water reaching the level of the rough threshold below the tile;

It seems that standards of practice have changed and that the rough threshold is often much lower than the height of the finished dam. Filling water up to within one inch of the finished dam can cause water to leak over the top of the waterproofing and falsely indicate a problem where none exists during normal use.

We have recently verified this problem with by removing tile from the outside face of a shower dam (which failed the required test) to visually see the level of the rough threshold and waterproofing. We found the waterproofing to be 3 inches below the top of the finished dam exactly as drawn above. When tested with water to the level of the visible waterproofing, the shower pan did not leak. When water was added to the shower test and rose above the waterproofing, leakage occurred almost immediately. We have concluded that the test required for Termite Inspectors seems to exceed building code in some cases and could result in unnecessary repairs and expense.

Water filled to top of measured waterproofing;

Water level was raised another 1/4 to 1/2 inch. Leakage began to occur almost immediately as water rose above the waterproofing. This was well before water reached one inch from the top of the dam as our flood test requires;

(click image above for more images of this test)

Communications have been made to the Structural Pest Control Board and the Pest Control Operators of California concerning this conflict. Hopefully there will be some alterations made to the current test to avoid such problems in the future. Such changes will take time. It will most likely be a year or more before any resolution is reached.

I have researched building code to try and determine the minimum height for the waterproofing of shower receptors. If I understand the Building Code correctly (411.6), the waterproofing is to extend to a point at least 2 inches above the top of the finished drain of the shower. If this was always the true minimum as shown below, the test performed by Termite Inspectors should not exceed 2 inches from the top of the drain.

Although, after talking to 2 different building departments, I get the impression that even this minimum has exceptions. Our policy, until an alternate test is developed, is to recommend further inspection and testing, before recommending repair, when a stall shower fails the standard "Flood Test." The last thing we want to recommend is to tear out a perfectly good shower.

If you have further information on this subject, please call me with your comments.

Thanks,

Mark Maxwell, President

Key Termite and Pest Control, Inc.

mark@keytermite.com / markmaxwell@vzw.blackberry.net

800-548-5599