This month I would like to discuss checking for moisture intrusion in tub / shower assemblies. I will concentrate on some of the items we can detect using our senses. I’m choosing to not discuss the use of moisture meters as I have seen many false positives using these devices when inspecting showers, particularly tile. Tile grout is porous. If the shower has been used recently, moisture will be detected behind tile, particularly mud-set tile (not to mention the metal lath setting off the moisture meter), as it drains to the tub or receptor. Moisture will be detected behind tile in cementitious backer board applications. The same is true for green board set tile. However, we know the expected life of this material is less than 10 years if the shower is used.

The first thing I do when inspecting a tile shower is get in the shower or tub and look at the tile; are any bulging (particularly at the sill if there is a window in the shower); is there grout missing; are any tiles missing? Does the shower area smell musty? Once my visual and olfactory senses are satisfied I use tactile manipulation (I gently push the tile with my hands) to determine the competency of the substrate. Some inspectors tap the tiles checking for lack of adhesion; I prefer “hands-on”. Pay particular attention to the first 5 or so courses of tile and around the valve(s). If the tub/shower unit is fiberglass I look for cracks; unusual deflection when I stand in the unit and I check for caulking at the top of the unit to the wall if it is surface mount panels. Often moisture will condense on the drywall above the panels and migrate behind them if not sealed.

In all types of units I check for proper sealing of the penetrations such as the shower valve, shower head, etc. I look especially close at recessed soap dishes. I have yet to see one fitted with a proper flashing flange. Often they protrude from the vertical shower wall and interrupt the flow of water, creating a dam and increased opportunity for water to enter the wall. Often the soap dishes are loose. Obviously, care should be used when “tactile sensing” any components to avoid breakage.

Many inspectors check for reverse slope at the edges of the tub. Typically reverse slope here is not a big deal as there is about a one-inch vertical leg built-in to the tub which extends behind the water resistant wall material. This is more of a nuisance defect, comparable to small ponds of water left in the bottom of the tub after use due to irregularities in slope. However, often if the outside corners reverse slope, or there are breaches in the shower door or curtain (with curtains it’s often operator error), moisture damage to the subfloor can be found at the corners of the unit. Some inspectors use foot pressure or an ice pick to check for damage at the corners.

One of my favorite items is windows installed in shower units with a sill below about 5-feet. The lower the sill; the more the potential for water intrusion. I have yet to see a window designed to be waterproof (flashed) from the inside. Often the window sill has flat or negative slope, directing water to the joint between the tile and the window frame – a sure way to guarantee leakage. Nearly every time I see a low sill window in a shower the sill tiles are buckling due to water causing swelling of the wood framing beneath.

Be sure to take the time necessary to use all of your senses when inspecting tub/shower units. Don’t forget to look at the baseboard for evidence of moisture in the closet adjacent to the tub/shower unit, often a few shoes need to be moved but the reward can be there.

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We’ll talk next month.         Read More Kaplan ITA Inspection Tips

Mike Casey
Kaplan Professional Schools