Yikes!”

“Uh-oh…”

The homeowner and I were watching our contractor remove deck boards that concealed an area of a foundation wall that we thought might have settled.

The homeowner had noticed a problem when the front door began to stick, and an unmistakable settling of the floor under the door had soon followed.

The contractor and I assumed that water had caused the foundation to settle, leading to a drop of the floor system — a relatively common problem in older homes that is sometimes easily stabilized and repaired

At this house, however, the problem looked much worse. A large section of the band board — a strip of lumber that surrounds the floor system — was completely rotted. We’d expected some damage to the band since we were sure that water (the cause of the rotting) was the culprit in the foundation settling.

But here the foundation looked intact. It was the band itself that had collapsed, causing the floor system to drop several inches. Worse yet, the damage extended well into the floor joists.

Ugh. Which one of us was going to give the homeowner the bad news — her minor settling problem in the house she’d recently purchased was rapidly becoming a very expensive major repair?

Not Aging Gracefully

Problems in older homes are often well hidden. More often than not, serious damage doesn’t show any symptoms until the damage is significant and expensive. There are clues, but even trained eyes sometimes have difficulty telling normal wear and tear from the signs of serious underlying problems.

Most old-home problems, however, have predictable causes and if you know where to look you can find hints that might lead you to discover concealed damage. Find the problems early enough and you might be able to fix them relatively easily, or keep yourself from buying into unexpected expensive repairs.

H-2-Oh No!

Water is the number one cause of damage in all homes, especially older ones. Look for missing or damaged roof shingles, rotted or loose trim boards, and disconnected or plugged-up gutters and downspouts.

Problems with gutters and downspouts are the biggest cause of water damage — they must be cleaned and checked regularly. If you’re looking to buy an older home, check the condition of the gutters and downspouts — they’re big clue to finding hidden water problems elsewhere in the house.

As the ground around a home settles naturally, it can slope in toward the house and begin directing water at the foundation wall. Modern waterproofing systems can delay the subsequent damage for a while, but older homes don’t have sophisticated waterproofing systems — if they have any at all. Many very old homes have porous stone foundations that have no ability to repel ground water.

Check the grade at the perimeter of the house — settling near the foundation may indicate water in the basement.

Plug It In

When your grandparents’ family gathered around the Philco radio in the 1930′s listening to the Jack Benny Show they weren’t putting much of a load on the house’s electrical system — the radio and a lamp or two may have been the only electrical appliances in the house.

But now there’s a TV in every bedroom; two or three computers; dozens of light fixtures; and a whole kitchen full of modern electrical conveniences. The appliances have grown — has the electrical system kept pace?

Each fixture or appliance “draws” power from outside in the form of amps; the more fixtures, the more amperage required. If the fixtures need more amps than the electrical system is rated for, the system can overheat, spark, or fail entirely — all potential fire hazards.

Any home over 40 years old is a likely candidate for having an outdated electrical system. Check the electrical panel for the amperage rating — modern homes require at least 100 amps and many require much more. Older homes may have “fuse boxes” rated for 60 amps or less.

Check any visible wiring to see if it’s made of aluminum, which is also considered a fire hazard and was discontinued decades ago.

Look around the house — are there lots of extension cords and plug adapters? Are there “burn marks” around some switches and outlets? Are there rooms without any outlets at all? Replacing an electrical system to remove safety risks or to bring the system up to current codes can be a very expensive project.

Home Sweet (Old) Home

If you own an old house, keep up with the maintenance to prevent costly repairs. If you’re thinking about buying one, check carefully for the signs of hidden damage and unsafe conditions first — a little detective work might keep you from saying “Yikes!” one day.

Richard Taylor is a residential architect based in Dublin, Ohio and is a contributor to Zillow Blog. Connect with him at http://www.rtastudio.com/index.htm.

Note: The views and opinions expressed in this article are those of the author and do not necessarily reflect the opinion or position of Zillow.