Foundation leaks difficult to find, fix

Q. I get water in my basement during rains and I think it is caused by leaking rain gutters. How do I trace the leak?

A. The basement water could well be caused by gutter problems, but I doubt that a simple leak is at fault. Leaks usually occur at joints, where sections of gutter are joined, or where fittings such as end caps are attached.

A leak will often cause stains on the underside of the gutter. Of course, you can always go outside during rain, using an umbrella, and check the gutters.

Leaks are not easy to fix. If you find one, clean the area thoroughly and caulk it with silicone gutter caulk, sold at home centers.

It is more likely that the basement water is caused by overflowing gutters resulting from clogs or sagging, or by downspouts that dump water near the foundation. A thorough gutter check usually means working from a ladder. Look for debris that can be causing clogs and make sure downspout openings are clear.

Sagging is cured by repairing or adding hangers or supports. Check for proper slope by running some water into a gutter’s high end with a hose; the water should flow readily down the gutter to the downspout and come out the bottom of the downspout. Clogged downspouts can be cleared with a plumber’s snake.

Also check the points where water exits the downspouts. If the downspouts empty close to the foundation, they could be the cause of your problem.

Add long downspout extensions or leaders, which will carry the water six or eight feet away from the foundation. If these get in the way of mowing the lawn, you can buy extensions that fold or telescope to get them out of the way.

An online source of telescoping, folding extensions is www.improvementscatalog.com (item 114918, about $19).

Q. I have an 18-year-old deck made of pressure-treated wood that is supported by 6- by 6-inch posts partially embedded in the ground. How can I tell if these posts need to be replaced? I understand that treated wood must be replaced every 20 to 25 years.

A. It is very difficult to accurately estimate the lifespan of any specific pressure-treated wood.

Your wood was treated with CCA (chromated copper arsenate), which was discontinued for residential use several years ago in favor of other preservatives. I have some CCA-treated fence posts that are about 30 years old, and they seem as strong and solid as ever. However, it does pay to be cautious about an elevated deck, which could cause serious injury if it collapses.

To test for weak or rotted wood, use a sharp ice pick or awl. Jab it into the wood, and if it sinks in easily, the wood is weak. If the wood resists the sharp point, it is probably still strong. In the case of partially buried posts, scrape away some of the dirt from the buried portion and test the wood there.

The best bet, if there is any doubt about the safety of the posts, is to have the deck examined by a structural engineer or an experienced deck contractor. If the posts do need to be replaced, you will need expert help anyway.

Q. My shower base has a crack from corner to corner and I suspect it is leaking. I had an estimate of $5,000 to fix it. Can I seal the crack myself?

A. You can seal the crack temporarily with silicone caulk, but that won’t solve the problem. Water has probably already leaked into the floor and ceiling below and can cause extensive damage in time, including rot and mold.

I’d get several additional estimates; you might get a better price that way.