Banish Moldy Oldies in your Home this Fall with HPM

Crawling insectoid pests are not the only things that you need to protect your home from - mold and mildew from excess moisture in, under, or around your home can be a costly problem that can cause damage to your home and bring illness to your family.

According to Energy.gov:

"Properly controlling moisture in your home will improve the effectiveness of your air sealing and insulation efforts, and these efforts in turn will help control moisture. The best strategies for controlling moisture in your home depend on your climate and how your home is constructed. Proper ventilation should also be part of a moisture control strategy.

Before you decide on a moisture control strategy, it helps to understand that moisture or water vapor moves in and out of a home in three ways:

  • With air currents
  • By diffusion through materials
  • By heat transfer.

Of these three, air movement accounts for more than 98% of all water vapor movement in building cavities. Air naturally moves from high-pressure areas to lower pressure areas by the easiest path available -- generally through any available hole or crack in the building envelope. Moisture transfer by air currents happens quickly, and carefully and permanently air sealing any unintended paths for air movement in and out of the house is a very effective moisture control strategy.

The other two driving forces -- diffusion through materials and heat transfer -- are much slower processes. Most common building materials slow moisture diffusion to a large degree, although they never stop it completely. Insulation also helps reduce heat transfer or flow.

The laws of physics govern how moist air reacts in various temperature conditions. The temperature and moisture concentration at which water vapor begins to condense is called the "dew point." Relative humidity (RH) refers to the amount of moisture contained in a quantity of air compared to the maximum amount of moisture the air could hold at the same temperature. The ability of air to hold water vapor increases as it warms and decreases as it cools. Once air has reached its dew point, the moisture that the air can no longer hold condenses on the first cold surface it encounters. If this surface is within an exterior wall cavity, the result is wet insulation and framing.

In addition to air movement, you also can control temperature and moisture content. Insulation reduces heat transfer or flow, so it also moderates the effect of temperature across the building envelope cavity. In most U.S. climates, properly installed vapor diffusion retarders can be used to reduce the amount of moisture transfer. Except in deliberately ventilated spaces such as attics, insulation and vapor diffusion retarders work together to reduce the opportunity for condensation in a house's ceilings, walls, and floors."

Homestead Pest Management of West TN has always offered vents, drains and plastic barriers as options for moisture prevention underneath your house to keep mold or fungus from developing. Contact Homestead Pest Management today to have a free underneath home inspection and get informed about all the moisture protection options applicable to your home. We are your West TN pest control experts, and we are here to help with all your pest control needs!

Summer Critters

In the midst of the warmer months of the year there is not much concern of pests that typically invade during the winter. After all, there is a lot of time to be spent on the lake, gardening and other fun-filled summer activities to pursue. But did you know that even when the weather is warm outside, rodents may still be trying to get into your home?

 

Although typically more of an issue in the winter when they need a warm place to reside, mice and rats are still in search of food during the summer which means they can still invade your home. When it comes to rodent infestations there are many concerns that should be considered even when the sun is shining and the warm weather abounds.

 

Gnawing on furniture, structures of the home, personal belonging, food packaging

Leave urine and droppings which leads to contamination

Can transmit diseases through droppings and biting

Cause fire hazards from chewing on electrical wiring

Can introduce other pests into the home such as fleas and mites

Clearly, rodents do not make good house guests regardless of the season and if you have been distracted by the long summer days (which let’s face it, we all have), it is possible that mice and/or rats may find their way into your Midwest home. Thankfully for homeowners, there are rodent prevention techniques as well as professional pest control services that are designed to keep mice and rats from breaking and entering no matter what time of the year. 

 

For residents who are living in the West Tennessee area including Jackson, Lexington, Milan and throughout our large service area, Homestead Pest Management is prepared to help protect your home from mice and other rodents. With our trusted home pest control services you can set your worries aside and rest assured our experienced team will get rid of rodents and many other common household pests. To learn more or to schedule your pest control service, please give us a shout today!

Moisture in your Crawl Space?

Do you have floor joists in your crawl space that look like the one to the right?  When you do, you'll notice the 'furries,' as one of my friends called the microbial infestation growing on that wood. What's going on here? Why is stuff growing on the wood down in the crawl space?

Well, it might be mold and here's what's necessary for it to grow:

  • Spores - They're everywhere and will grow if the other conditions are met.
  • Appropriate temperatures - They like pretty much the same temperatures we do, and even colder. Ever seen mold in your fridge?
  • Food - Organic matter is what they like, and it's everywhere. Mold likes cellulose (wood) and the more processed, the better. Paper is called mold candy by people who work in this field.
  • Moisture - To sustain growth, a mold colony must have water. When the relative humidity of the air is 70% or higher, mold has enough water to grow.

So, of the four requirements for mold growth, the one we have most control over is moisture. Keep the materials and the air dry enough, and we won't have a mold problem.

Have you measured the relative humidity in your crawl space? When I was doing improvements on homes, I'd install a digital thermo-hygrometer with a remote sensor in the crawl space so the homeowners could track the relative humidity. If you're not doing this yet, and you have a crawl space, get yourself one of these devices now.

OK, so you've measured and determined that you do have high relative humidity in your crawl space. That's not unusual at all, especially in a humid climate like we have here in the Southeast. Where's the moisture coming from? And why is the humidity in a vented crawl space higher than the outdoor relative humidity? Here are three reasons.

1. Bulk Water

 


The first problem to look for is bulk water. If there's standing water in your crawl space, you have either a drainage problem or a plumbing leak. You need to fix this immediately. Having a pond under your home is a bad, bad idea.

In the photo above, the problem was that the back yard sloped down to the house, bringing water up to the foundation wall. Since it was just a crawl space, the builder didn't put any kind of water proofing on the concrete block or grade the yard properly to keep the hydrostatic pressure from building up against the block wall. You can see the result here. This was a new house with a serious bulk water problem. The joists were already growing stuff, and the fiberglass batt insulation was getting heavy and falling down.

2. Moisture Evaporating from the Ground

moisture problems wet soil crawl space high humidity

In the photo above, the ground was partially covered with a polyethylene vapor barrier. The dirt that wasn't covered looked dry, but when I pulled the plastic back, I found that there was a lot of moisture in that soil. The soil that looked dry only looked that way because it was constantly evaporating moisture into the air of the crawl space. The foundation walls can also evaporate moisture into the air.

What do you do to solve the problem? Cover it all up with a vapor barrier!

3. Outdoor Air Coming in through the Crawl Space Vents

Some people find this hard to believe, but when you bring outdoor air into the crawl space, the relative humidity actually increases. Think about it this way: When air enters the crawl space, it cools down. Cool air cannot hold as much moisture as warm air, so the air that enters is now closer to its saturation point (which we call the dew point). It might've been 60% relative humidity outside (relative to a temperature of 90° F, say), but when that air came into the crawl space and cooled down to 75° F, the relative humidity jumped up to 95%. Not good!

The numbers here come from the psychrometric chart (invented by Willis Carrier, the inventor of the modern air conditioning system), which relates temperature and humidity of air.

What Can You Do?

If you've got a vented crawl space with high relative humidity caused by one or more of the above, to solve the problem, you've got to remove the causes. Bulk water is solved by fixing the drainage or plumbing problems. Water evaporating from the ground or coming through the vents can be fixed by encapsulating your crawl space.

One thing that does NOT work is to try to treat the symptom by installing a dehumidifier. Don't do that!

 

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