A properly constructed crawlspace will be clean, have low moisture levels, and free of prevent allergens and contaminants rising into the house. Today, almost all modern crawlspaces have vents placed in the walls for ventilation and keeping it dry.
This is fine during the winter months. However, in the summer months, the high humidity can be an obstacle. Let’s say you have 90-degree air at 70% humidity (typical summer conditions). Cool it down to 70 degrees (typical crawlspace temperature) and the humidity level in that same air changes to 100%.
It’s estimated that about 40% of the crawlspace air enters the house. This impacts your indoor air quality significantly. Especially for anyone in the home who suffers from allergies, asthma, or any other respiratory issues. To prevent this from happening, your crawlspace needs to be sealed entirely from the ground and outside air. This will increase indoor air quality and annual energy savings by 10% – 15%.
With properly sealed crawlspaces, the humidity level is controlled with a small amount of air from a supply on the HVAC system or a small dehumidifier. The ground is covered with a thick layer of plastic. The vents and mud sill (wood at the top of the foundation wall) are sealed from the inside. To top that off, a high-quality access door is built with treated wood and provided with proper latching mechanisms and weather stripping. From the outside, everything looks as it did before.
To keep your crawlspace at its best, a smart humidity sensor is installed. This allows you or BPS to monitor the temperature and humidity of the space. By monitoring the humidity level, you can prevent moisture-related damage to your home. The sensor will send you (and us if you share your sensor data with us) a text message and/or email if the humidity in that space gets above the level we have set.
The monitoring system will also tell you if it loses communication for more than one hour or if the batteries are low. This is to avoid any sort of surprise moistsure problem. We have had numerous occasions where we were alerted that there was a problem before there were any signs of trouble, including a plumbing leak discovered through one of these systems in the crawlspace of a newly-built house.
“What’s the difference between a sealed and a closed crawlspace?” A sealed crawlspace liner is thicker. They are sealed together with caulk and tape, and then sealed to the foundation walls and piers. In a closed crawlspace, the liner is thinner. It is overlapped and staked down, but not sealed.
“Which one should I get?” Due to the labor involved and the working conditions, a sealed crawlspace is more expensive. However, they are the best choice for those who suffer from respiratory issues and need the ground completely sealed off from the crawlspace and house above. If a respiratory illness is not an issue for your household, a closed crawlspace is all you’ll need.
“I’m in a flood zone so I can’t have a sealed crawlspace.” We regularly install sealed and closed crawlspaces in houses in flood zones. It’s entirely possible to have vents that keep air out but let water pass through in the event of a flood.
“What kind of dehumidifier should I get?” A low capacity, Energy Star rated, portable dehumidifier will be efficient. Replacements are easy and inexpensive. However, we do not recommend digital dehumidifiers because they will have to be reset after the power returns after an outage. If your crawlspace is vented, you do not need a dehumidifier! You are dehumidifying the great outdoors!
“What should the humidity level be in my closed crawlspace?” We set our dehumidifiers between 68% and 70%. We commonly see crawlspace dehumidifiers set lower than necessary. Levels around 50% are more likely to cause issues if you have hardwood flooring. We have seen crawlspaces run above 75% (where we set our notification alarms) for weeks at a time with no problems.
“What should I do about the mold in my crawlspace?” First, we all have mold in our crawlspaces (even if you can’t see it). When mold testing is done, it is measured against the levels around your house. If the mold levels in your house are at or below the levels around your house you are considered safe. The homeowner is the only one who can make that personal decision for themselves. Depending on particular sensitivities and comfort levels. If any mold removal is done, it must be completed before the crawlspace is sealed and the permanent liner is installed. We work with an industrial hygienist to perform pre and post-testing. A remediation plan is written and then followed by a certified remediation contractor.