Trapped moisture is your home's worst enemy

March 2023

When you think of disastrous things that can happen to a home – earthquakes, fires and windstorms come to mind. However, the enemy that does the most damage to most homes is none of these. It’s trapped moisture!

We’re not even talking about a burst pipe – which of course is also a concern – instead we’re talking about the kind of moisture that comes from wet jackets and shoes, watering house plants, cooking, showering, wet pets, house leaks and more.

As those sources of moisture evaporate into thin air, they travel through the house until they find a cool wall surface, toilet tank, or even a thermal pane window to turn back into a liquid state. We are sure you have seen it happen!

When this water vapor finds these cool lower corners of rooms, bottom walls of closets and certainly anywhere in an unvented bathroom, it sticks and stays, creating an environment for mold and mildew. None of this is good and it can be pre-vented – literally.

Moisture is tough on houses!

You may assume much of what you see in and around homes is just normal wear and tear — things like peeling paint, curling shingles, rotted skirting, mold, mildew and bug damage. These are not normal and can be prevented with proper ventilation and timely maintenance.

The good news is that specific vents can be installed in your roof, foundation, bath and kitchen to take care of the excess moisture.

Adequate ventilation is key

So, how do you know if your house is adequately ventilated?

Homes in our area should have one square foot of ventilation for every 150 square foot of foundation floor area. Same for the attic using roof vents. For example, a one-floor 1,200-square-foot house, divided by 150, would need 8 square feet of ventilation around the perimeter of the foundation and again in the roof.

This can be achieved by adding 1-square-foot foundation vents at every corner and evenly spaced around the foundation or skirting. For the roof, we recommend ridge and soffit venting, but there are other ways to get the job done.

Inside the house you should have a powered fan in the kitchen and each bathroom that is properly vented to the outside. While openable windows can help, they are not as efficient and only work if opened.

By installing these vents, you have taken some of the preliminary measures needed for a healthier home and you.

Look under the house!

How can you tell if your home’s foundation has trapped moisture? Well, there are some tell-tale signs.

If you see lots of spider webs, that usually indicates high moisture content in the air and may indicate you need more ventilation and/or a ground cover. Installing 6-milimeter black plastic on the ground under the house stops this moisture source, instantly.

Next, place a splash block or a pipe at each downspout to convey water away from the foundation.

If you find a water puddle on the plastic you need to play detective. If it is gray, filmy or soapy water, it means a sink, tub or washing machine drainpipe could be leaking. Operate each fixture, to find the leak point and repair it.

If the air smells or looks like toilet water, call a plumber! That water is hazardous to your health!

A puddle of clear water on the plastic can be from rain through a vent or a water supply line drip. First look at the water meter ‘tattle-tale’ and see if there is a leak indicated. The ‘tattle-tale’ commonly refers to the small triangle in the older style meter window which spins when water is passing through the meter. In order to check this, make sure all fixtures including sinks, tubs, washing machine, extension hoses, etc. are shut off. Now look at the water meter. If all fixtures are off and the counter on the water meter (or the little triangle on older models) is turning the ‘tattle-tale’ is indicating a leak somewhere as water is going through the meter when it should not be. If not, look for another source and the reason why, like rainwater.

If you have a lot of ground water you may need a sump pump to carry it away from the house but avoid sending ground water into the city sewer system. Big No-No!

Other issues to deal with

If you observe any signs left behind by critters—like ammonia cat pee smells, feces, hair or tracks, then secure openings and fill under the edges of the skirt. All soils should slope away from the house to help channel water away from the foundation.

Finally, there may be small sawdust trails and holes peppering the wood, or larger holes that other pests make. Poor ventilation and/or a steady

source of moisture on wood can create conditions known to attract pests. The bottom line is that you need to get rid of these pests and the moisture sources that allow them to be there! That may require the knowledge and products that pest control professionals use.

Depending on the level of damage, a professional pest spray, proper ventilation and removing all sources of moisture could cure the problem. Don’t wait too long. If you do you may have to replace your entire foundation, sub-floor and skirting.

What about siding?

Your home’s siding protects it from nature’s fury, just as your clothes protect you. When properly installed and maintained, the siding materials used on your home are generally durable and long lasting.

However, bad paint, sunlight, damaged siding, poor caulking and rusted flashing, in addition to moisture build-up can damage your house! The good news is that good ventilation and timely maintenance can make all the difference!

If you discover missing or damaged siding or trim, it’s important to repair and replace these materials to avoid moisture problems and further damage.

Also, pay close attention to broken or missing window parts. With wooden windows the sash surrounding the glass panes must be kept well glazed and painted. The sill sheds the rain away from the siding and must be smooth, rot-free and well painted to do its job well. The trim boards around each window make a weatherproof transition from siding to glass. They must also be tightly caulked and painted. When these parts fail, it can result in leaks then wall and floor damage.

Moisture in bath, laundry

Other ways to control the moisture inside your home include leaving the bathroom fans on for a half hour after you are done with your shower or bath.

Also, make a habit of opening your windows and airing out your home, when weather permits, especially after you have been doing laundry, cooking, or washing your floors. It will make a difference in protecting your home.

Eric Bjella is the executive director of NeighborWorks of Grays Harbor, where Pat Beaty is the construction manager. This is a nonprofit organization committed to creating safe and affordable housing opportunities for all residents of Grays Harbor County. For questions about home repair, housing counseling for renters and landlords, homebuyer education and financing, call 360-533-7828. Our office, 710 E. Market Street, is open to the public from 8 a.m. to 4 p.m. Monday – Thursday.