Signs of excessive crawlspace humidity include: Wood moisture levels exceeding 20% (measured by a moisture meter) Insulation drooping or falling. Dark stains on floor joists.
How Much Moisture Is Too Much In My Crawl Space? Experts suggest keeping your crawl space moisture levels below 28%. Anything higher can lead to wood rot and mold, turning your crawl space into a damp and musty environment.
According to the ASTM standards, recommended concrete moisture levels are a relative humidity (RH) of 75% or below or whatever the manufacturer of the floor covering specifies. Many manufacturers may allow for RH levels that are above 75% as some floors may be more durable than others.
Proper Crawl Space Humidity Levels
Maintaining your crawl space at a level of under 65% humidity keeps the air healthy. Here are a few of the bad side effects of high humidity in your crawl space: Wood rot. Mold and mildew growth.
A moisture meter reading above 16% is generally considered damp, with higher readings posing greater risks. For plaster walls, readings over 20% may indicate significant water ingress, often caused by leaking pipes or external wall defects.
Readings of 5 to 12% are considered normal, and up to 17% is considered acceptable. Wood starts to rot and is susceptible to mold when its moisture content reaches 35 to 50%. Wood can typically hold up to 25% without showing signs of deterioration.
Moisture meters help detect moisture spots with possible mold growth. If your MC reading in wood is more than 20%, you may want to check these areas for mold growth. When the MC is above 20%, this is possibly where mold growth can start to happen. Humans have reason to attach negative connotations to mold.
High humidity (60% relative humidity).
Protect Your Crawl Space With Alpha Foundations
Crawl space fans are ineffective at keeping crawl spaces dry. In fact, they can accelerate moisture issues below your home. For a lasting solution, consider installing crawl space encapsulation.
One way to determine if your crawlspace has a moisture issue is to check the wood moisture content using a wood moisture meter. These handheld devices are able to tell you if your subfloors and floor joists are holding excessive moisture. Readings between 7%-19% wood moisture content are considered normal.
Since most concrete floors have a vapor retarder below them, this moisture must move upwards in order to escape. The significant movement of water within the slab means that the moisture condition will vary by depth.
The critical moisture content is the average material moisture content at which the drying rate begins to decline. A prototype drying test should be conducted to determine the critical moisture content.
All foundations settle to some extent, even crawl space foundations. However, if water is pooling, floors are sagging, and cracks are forming, it might be a sign of serious structural damage. Cracks are letting excess moisture into your crawl space, which can cause your floor boards to rot and your home to sink.
Even if you have a vapor barrier in your crawl space, the water will sit on top of the liner until it evaporates. What to Do: The best way to get rid of standing water under the house depends on whether you've got a few puddles or a crawl space full of water. But water in the crawl space won't go away on its own.
If there is water in your crawl space, expect to pay between $2,000 and $10,000 to have it removed and repair any damages. If you identify the problem and fix it early, the costs may be low, but the longer you wait, the more damage the water can do.
The temperature in your home
Keep doors of unheated rooms open to allow some heat into them. Ideally your home should be heated between 18 to 21 degrees Celsius, but older people, babies and people who are less mobile may need it to be warmer.
If you suspect mold in your crawl space, it's always best to reach out to a professional mold remediation company. PuroClean can safely and effectively deal with mold in crawl space. If the mold affects an area smaller than 10 square feet, there are some steps you can take to treat the mold yourself.
What is the Best Humidity Level for your Crawl Space? Many homeowners ask this question and get very different answers depending on where the answer is coming. We at Crawl Space Ninja feel like the range of humidity should be between 45% and 55% in most cases.
It's important to always keep the goal of moisture management in mind when addressing issues. For these reasons, we want to keep crawl space wood moisture below the 20% range.
A wet crawl space could take a total of eight to 10 hours to dry. Warm, moving air picks up moisture more readily. To speed up the drying process, place a source of low heat, such as a light bulb, inside the crawl space and position one or more electric fans where they'll blow air across damp surfaces.
Moisture will condense on the crawl space walls and other materials inside. Depending on how humid the air is, puddles may form. Again, this is normal. If the humidity is more than 50% for a number of consecutive days, then you have reason to worry.
You should be aware that a moisture reading of 0-15% is quite normal and gives no cause for concern. However, moisture readings in excess of 15% indicate the need for further inspection. Levels between 25-30% indicate that there may be water ingress, meaning that remedial work could be required.
A concentration of mold spores above 500 sp/m3 is considered high. Therefore, if your report comes up with high concentrations of mold, it will likely advise you to remediate the problem. However, it is important to note that even low concentrations of mold spores can cause health problems in some people.
First, test the moisture level of the subfloor. In general, 12% moisture or above is too wet to install flooring. Ideally, it should be between 7% and 9%. Take the readings in at least 20 spots per 1,000 square feet of flooring and average the results.