THE DREADED L-WORD: LEAKS

If your roof leaks,  don't panic and assume you need a
whole new roof. Look for common problems like this
leaky plumbing vent jack. It could be the difference
between a repair costing ten bucks, or ten thousand bucks. 

Nothing strikes fear into a homeowner like the dreaded L-word:  Leaks. But the fact is, every house has leaks of some kind. It’s just that they’re usually so minor that we aren’t aware of them. 

The most common way for water to enter a house is, of course, through roof leaks. But as I’ve noted many times, it’s almost never the roof material itself that’s leaking. Rather, water usually enters wherever the roof is penetrated—at vent pipes, flues, chimneys, and at junctures between roofs and walls. Hence, replacing your whole roof to solve a few minor leaks is usually an enormous waste of money. Most small leaks can be repaired just as effectively with a three-dollar tube of calk.

Attic louvers—in fact, just about
any kind of louver—will leak under
strong wind and rain conditions.
Don't sweat it. A few drops of water
won't do much harm in the long run.

But roof leaks aren’t the only way water can get into your home. Here are some other favored routes for the dreaded L-word:

•  Many skylight “leaks” come from water vapor trapped inside the house, not from rain. When the weather gets cold enough, vapor from cooking, showers, and the like can condense on the underside of a skylight bubble and drip down. For this reason, modern skylights have an integral condensate gutter around the inside edge to catch the “leak” before it hits your floor. From there it either drains out onto the roof through a little weep hole, or simply evaporates when the weather warms up.

•  Louvers, such as those used to ventilate attics and crawlspaces, will often leak a little during any rainstorm that’s combined with a good strong wind. It’s normal, and there’s not much you can do about it. The small amount of water that enters seldom does any real harm, and quickly evaporates.

Close up view of composite drainage sheet system. The
knobbed sheet allows water to drain away easily.
The filter fabric blanket keeps soil out of the passages.

•  Basement or crawlspace leaks are more difficult to solve, and can do a lot more damage than any of the foregoing. Usually, these leaks come from water-saturated soil that’s in contact with the basement wall, creating  hydrostatic pressure and making the wall act essentially like a dam. The solution in most cases is simply to offer the water an easier exit than being forced through the wall itself. 

One common solution involves excavating along the outside surface of the leaking wall and sealing it with a moisture-resistant material such as bentonite clay; then putting a perforated drain line in the bottom of the trench and leading it to an appropriate outlet; and finally backfilling the trench with gravel and placing a few inches of soil on top. Then, when the soil becomes saturated, the water will migrate via the path of least resistance: through the gravel and into the perforated drain pipe, rather than through the less permeable wall. 

In lieu of gravel, another approach is to use composite drainage sheet systems such as Delta Drain, Miradrain, or Hydroduct. All of these come in rolls, are relatively lightweight, and are installed directly against the basement wall. They all use some form of knobbed plastic sheet that creates a space in which water can easily drain away. A filter fabric adhered to the outside face of the drainage sheet prevents dirt from clogging the drainage passages.

If you have galvanized steel pipes such as these
in your house, leaks are a foregone conclusion.
Replace them if you get the chance.

•  Plumbing leaks are—mercifully—a fairly rare source of unwanted water. They can arise from either drain or supply piping and can be a real bear to fix, since the pipes are usually hidden inside floors and walls. If you have old-fashioned galvanized steel plumbing, eventual leaks are almost a given, so you may want to consider re-plumbing your whole house with a more durable material such as copper.

The joints of old-style bell-and-spigot cast iron drainage pipe can leak too on occasion, but unless you’re a whiz with oakum and rammed lead wool—and who isn't these days?—they’re hardly worth repairing with the original materials. Usually, the simplest course is to replace the offending area with a new section of no-hub cast iron or, if your local codes allow them, with ABS or PVC drainage pipe.