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Find That Leak

Discovering you have a leak in your bathroom is not nearly as difficult as finding where that leak is. Here are a few tips to start your investigation.

It happens one day while you are absorbed in a daydream---staring absently at your ceiling you notice it--a watermark. Something is leaking from your upstairs bathroom. Avid do-it-yourselfers tend to pull out the caulking gun and re-caulk the entire bathroom. This usually creates quite a mess, and only occasionally solves the problem. The other extreme is calling in a contractor to fix the leak, which will probably solve the problem, but comes with a pricey bill.

The best thing for a do-it-yourselfer to do is to try to recreate the leak. First, begin checking the shower drain line to see if that is the culprit.

Piping is rarely the cause of the problem, but since it is easy to check you can at least rule out that problem. Pour several gallons of water down the drain and see if the leak begins again. Be sure not to spill the water on any part of the tub. Use of a garden hose or a funnel may be helpful during this step. If the spot on your ceiling isn't leaking at this point, that's a good sign, meaning your piping is intact.

The next step is to check the chrome flange in the bottom of the tub that connects the shower body to the drainpipe. Pour water around the flange so that it is completely immersed. Generally, the flange is screwed into the drainpipe in a bed of caulk. The caulk covers the slight recess around the drain, which is where the flange will sit flush with the shower floor once it's tightened down. If this caulking cracks, water can drain through the shower floor and outside of the drain line, which can rot out the subflooring supporting the shower base. If your leak occurs here, you can easily fix this problem by unscrewing the flange, clearing out the old caulk, laying a bed of silicone caulk, and reinstalling the flange.

One trick to remember is to use enough caulk so that extra oozes out on all sides of the flange as you tighten the fitting. When the caulk dries, strip away the excess.

If you still haven't found your leak, the odds are that it is probably coming from the seams between the base of the shower and the wall. To test this, flood these seams. If you can reproduce the leak, caulking may help.

It's worth a try before you tackle the big (and expensive) job of replacing a shower base, or the pan under a tiled base. You might be able to stop a leak by scraping out the old grout or caulk and installing new material.

And if you are still at a loss for locating the leak, try one more test. Douse the walls with spray from the showerhead, including the door or the side of the tub where the shower curtain hangs. This test may indicate that water is not leaking through the shower floor at all, but actually outside of the stall or tub. Water can seep through the vulnerable seam where the shower base meets the bathroom floor. Grout, because it is not flexible, does not last long in seams between a shower or tub base and the walls or the floor. Grout requires rigid support to keep from cracking, and these seams do not stay rigid all of the time-they flex as you step in and out of the shower, or fill the tub with water. You can prevent these problems by grouting the tiles up to these seams, and then filling the final seam with a flexible caulk, such as silicone.

Once that leak is found and repaired, you can get back to staring at your ceiling. If you're really particular, though, you may have some repainting to do before your daydreaming can continue in earnest.

Sources: Mike McClintock, The Washington Post