In many older houses, one can observe that crawl spaces used in the rooms that were extended beyond the main foundation of the house, on added on rooms and sometimes entire houses built on a crawl space with an exposed soil bottom. There are two reasons behind this type of construction. The first reason is that it was less expensive to build because less excavation and smaller and foundation walls and the other is that wood framed floors made more comfortable living spaces. Concrete floors were not very popular in the past due to the cold, hard surface.
A crawl space provides a natural insulating air barrier between the ground and living space. There are several instances that water damage and molds have started from crawl spaces. The reason behind this is that in some homes, crawl spaces are rarely accessed or used. Thus, unintentionally, we overlook its functionality and its maintenance as well. Just like every other part of the house, a crawl space should be given the same attention as well. When neglected, a crawl space that is not properly moisture controlled can cost you a lot of money. Your home will be susceptible to rot, molds and insect damage. In addition, a non-moisture controlled crawl space is energy inefficient, which translates into higher heating and air conditioning bills. If the air conditioning units or your heating system is located in the crawl space, it may be damaged due to high moisture content.
Crawl spaces can be found with or without operable ventilation systems. Though venting, a crawl space may seem to have reduced moisture levels, though it actually can cause more harm than good in hot, humid climates. A vented crawl space located in a hot, humid climate may actually increase the humidity level within the crawl space and make it more susceptible to moisture damage. The moist, hot air reacts with the cooler air in the crawl space and causes condensation.
The condensing moisture attaches itself to floor framing surfaces where mold can begin to form and eventually become its home environment if not prevented. Though the rules can vary depending on your local climate conditions, there are several basic steps you should do to minimize the moisture levels in your crawl space. If you are about to build a home with crawl spaces, putting a perimeter drain around the foundation wall when installing the crawl space foundation will help to control moisture by letting the water run away from the outside foundation walls.
You need to make sure you seal the outside of the foundation walls to finished grade level with a waterproof sealer. When backfilling in around the foundation, make sure the finished grade gently slopes away from the foundation walls. See to it that the floor of the crawl space is covered with a 4-6 mil layer of polyethylene vinyl (plastic) to reduce moisture transfer from the ground into the crawl space area. The seams must overlap by 1-2 feet and should be taped. The plastic should go up the sides of the wall of the crawl space approximately 6-12 inches.
To finish with, add 2 inches of sand over the plastic to minimize the risk of breakage. These steps will help to reduce the moisture that may possibly form in your crawl spaces. For houses that were already standing, these steps may not be applicable anymore. You do not have to worry because you can still prevent moisture buildup and you can even do it by yourself. This is done by insulating your crawl spaces by putting moisture barriers. Simple and easy, you will need the following: a tape measure, a utility knife, a steel framing square with a cutting edge, a hammer, a staple gun, insulation and the plastic vapor barrier. For your own protection, it is strongly advised to use a dust mask, gloves, and eye protection(goggles). Now that you are fully equipped, follow this instruction carefully.
- Look for holes and cracks in the exterior foundation and repair/patch them. This is to prevent water by leaking in.
- Repair any leaks in supply piping that can be found in the crawl space.
- If the crawl area is more than 30 sq.ft. of contiguous toxic or allergenic mold it should be cleaned by a professional mold remediation company before the insulation start
- Remove crawl debris that may be present in the area.
- If there is room to work, a power washer is a very effective way to clean surfaces, but the increase in water and moisture in the crawl space can make mold or other building-related moisture conditions worse so complete drying must follow.
- Negative air machines and dust barriers are procedures used by professional mold remediation companies, asbestos removal experts, and flood damage restoration companies where you can ask for help. These measures will reduce the risk of blowing contaminated dust and debris into other building areas - an event which could be a health risk, especially to occupants who are in fragile health. Complete cleaning should be done first before the process starts.
- Check exterior drainage at the crawl space foundation and make sure that it is sloping away from the house. You may need to fill in more soil or concrete to grade away the slope if the slope is towards your house. The reason behind this is your home may get flood should heavy rain fall.
- Add vent to exterior to enhance air exchange. After adding vents, you can use a portable fan in the next couple of days to remove moisture before pouring the slab. Fan will help circulate air and remove moisture.
- If there is no concrete slab in your crawl space, lay a vapor barrier on the top of the exposed soil overlapping joints for about 6”. A vapor barrier is usually a 4-6 mil polyethylene (plastic) sheet that helps trap the moisture.
- After this, install a rigid foam insulation board flat around the perimeter.
- Now that the vapor barrier was laid, pour a concrete of about two to three inches thick to cover vapor barrier on the floor.
- For better result, you may opt to add a rigid insulation board to the interior of the foundation walls.
- Now insulate with fiberglass insulation rated R13 or higher.
- It is advisable to use a KRAFT insulation vapor barrier and install with the vapor barrier towards the living space.
- Use joist wires to hold insulation on its place. Take note that the paper side is facing up hence there is no place to it.
- Lastly, insulate any pipes and ducts in your crawl spaces.
In order to minimize the affects of the colder drier air in the crawl space you may want to insulate the “roof” of the crawl space as well. It is simple and easy; basically, you just need to install rolled insulation between the floor joists. The rolled insulation does not require a moisture barrier surface, as the plywood floors above act as a moisture barrier itself.
After you have installed the rolled insulation, you should cover and staple it with a layer of polyethylene vinyl to create a vapor barrier between the bottom side of the insulation and the crawl space airspace. Take note that when installing the rolled insulation you use insulation hangers to secure the insulation in between the floor joists. Do not just rely on the friction between the floor joist and the rolled insulation to hold the insulation in place.
Now that you have successfully installed your insulation that will serve as moisture barriers, you just need to maintain them to maximize its usage. During the hot summer months, you must seal off the vents in the crawl space to minimize the influx of hot moist air that would otherwise condense in the cool crawl space area. Likewise, during winter months, seal off and insulate the vents of the crawl space to reduce the threat of cold air that could freeze pipes in your crawl space. When spring and fall come, open the vents of the crawl space to enable moisture within the crawl space to dissipate.
Installing and maintaining moisture barriers for crawl spaces is easy and simple. All you have to do is to devote a little time to make it happen. Installing it is not enough though. Maintaining and proper use of the crawl space will help maximize their use. By taking care of your crawl space, you are taking care of your most valuable investment as well - your home.
A crawl may not be often visited, but it does not mean that it has no use and it is right to take it for granted. You can hire a professional to help you with the process but it would be advisable to do it yourself since it is an easy to do.
You will be saving a lot by doing it by yourself. It is just a matter of time and devotion.