In the Wall Beneath a Window
Windows are a prime spot for water leaks. Rain can seep in between the window sash and the jamb and trickle down to the framing studs in the wall without your ever knowing it’s happening. Over time, repeated leaks can rot wall studs and other wood framing members, which can lead to expensive repairs.
Under the Siding
Common locations for water leaks in siding are at the corners of the house, anywhere two siding panels meet, and around the windows where the siding abuts the trim. Unsealed gaps in these spots allow water to trickle beneath the siding and eventually rot the plywood sheathing that lies beneath. The damage may remain hidden until the siding is replaced.
Exterior Door Threshold
The wood beneath the metal threshold of an exterior door is subject to saturation every time it rains. While treated wood is often used for this application, even treated wood will eventually swell and become spongy when continually exposed to moisture. Damage may not be noticed until the metal threshold starts to work loose when the wood beneath has begun to rot and can no longer support it.
Exterior Painted Windowsills
This is a common spot for water damage in older homes with windows that have been painted numerous times over the years. Just a tiny trickle of water through cracks in the paint can slowly rot away the wood without your noticing. To check for problems, take a screwdriver and press firmly along a sill. If there’s hidden damage, the screwdriver tip will sink into the soft, damaged wood.
Beneath the Dishwasher
Dishwashers are sealed to keep the water inside the tub, but leaks can develop in the joints of the water supply line that runs to the dishwasher or in the drain line beneath. Because you can't see under the dishwasher, over time a slow leak can do serious damage to the subfloor. The damage may not be discovered until you remove the dishwasher to replace it with a new one and realize, to your annoyance, that you'll have to replace a section of the floor as well.
Next to the Tub or Shower
Wherever water lines run within walls, there’s a chance for leaks to develop. While modern plumbing techniques have reduced the risk, plumbing connections (where pipes attach to other pipes) still have the potential to spring a leak. You won’t have a clue that this is happening unless water begins to pool beside a fixture or the floor near it becomes spongy because the subfloor is rotting.
Related: 15 Problems Hard Water Can Cause
Under a Wobbly Toilet
To help seal the connection, a wax ring fits between the base of a toilet and the toilet flange that connects to the drainpipe beneath. The wax is soft and pliable, which makes it well suited for this job, but also means that it can leak over time. If there's a problem with the wax ring, you may notice a little bit of water around the base of the toilet, but it's more likely that you won't see any water at all—although it will be soaking into the subfloor all the same. In fact, the first indication that you have a problem may be a toilet that starts to wobble because the floor supporting it is rotting away.
Under the Sink
A slow drip from a water line or the drain line beneath a kitchen or bathroom sink will often go unnoticed until a musty smell alerts you that something’s not right. Because the area under a sink is dark, it’s a prime place for mold to develop when moisture is present. It’s a good idea to check regularly under sinks with a flashlight to ensure that a slow drip isn’t causing mold to grow.
Behind a Bathtub Surround
Unless your bathtub is a single, molded unit, there a good chance the caulk between the tub and the surround will one day fail, allowing water to leak in and damage the wood studs and framing materials. Keep an eye on the condition of the caulk, and if it’s starting to yellow or pull away, remove it and replace it with fresh new caulk.
Behind Drywall After Flooding
Any time flood waters rise above floor level, whether it’s from high rains or a burst water supply pipe, all drywall along the lower portion of the wall should be replaced. Even if the water subsides quickly and the wall looks fine, mold can be growing within the stud spaces. Keep in mind that the electrical wiring may also have been damaged.
Around a Chimney
Roof penetrations, such as for chimneys, vents, and exhaust fans, extend through the shingles and roof deck. If they aren’t properly sealed, water can seep in and damage the roof deck without anyone noticing. Having the roof professionally inspected annually will help pinpoint problems around penetrations so they can be repaired before you’re on the hook for a complete roof replacement.
Inside an HVAC Unit
The indoor part of an HVAC unit features a shallow pan that collects condensed water that forms on its evaporator coils when the air conditioning is running. From there, the water is directed to a floor drain via a small line. If this line becomes clogged—unfortunately, not a rare occurrence—the water accumulates in the drip pan or even overflows, creating the perfect environment for mold to develop inside the HVAC unit.
Behind an Exterior Faucet
Exterior faucets are hot spots for hidden leaks because the faucet connects to a water pipe just beneath the siding—a place where it's difficult to make a secure connection. If a leak develops here, the water often runs down the inside of the wall, where it can do major damage to sheathing and framing members before it’s discovered.
Behind the Washing Machine
When a homeowner hooks up a new washing machine, its hot and cold water hoses attach to valves already installed in the wall. These coupling are similar to those on garden hoses, and if they’re not attached snugly, or if the rubber washer in a coupling fails, they’re prone to leaking. Once the washing machine is in place, the valves are typically hidden behind the machine, and a slow leak can saturate the drywall unnoticed, destroying it and allowing mold to develop.
Below a Window Air Conditioner
Air conditioners remove moisture from the air as they cool it. The moisture, or condensation, is then directed through a tube to the outside of the house. As a window air conditioner ages, the tube can become clogged, or come loose entirely, causing the condensation to spill out of the unit and drain into the wall space below, rotting wood studs and sheathing without anyone knowing what’s going on.
Keep an Eye Out
Know the trouble spots, and the tell-tale signs.
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