With winter right around the corner, many of us start looking at various ways to reduce heat loss and improve energy savings. One of the most common practices of improving energy savings is by installing or improving our homes insulation. This is especially true for those of us who have the luxury of living above a crawl space. Installing or improving crawl space insulation can be very beneficial. But it can also have expensive, negative effects if not done correctly. Here is a list of a few common crawl space insulation ideas that have the potential to cause much more harm than good.
1. Fiberglass Insulation Between The Floor Joist - This is one of the most common methods of insulating a crawl space. It is also one of the most effective ways of improving energy savings, but only if done correctly. Too often fiberglass insulation is installed between the floor joist in a crawl space without considering any other factors of the environment in the crawl space, mainly moisture. If your crawl space has standing water or excessive moisture, than I would recommend not installing fiberglass insulation between the floor joist until these moisture problems are solved permanently. This is because moisture in your crawl space eventually makes it's way up into the living area of your home by a process known as stack effect. Fiberglass insulation between your floor joist will work like a sponge, absorbing and holding this moisture. This will cause the insulation to lose it's R value. It will also cause it to become heavy due to the moisture and fall. Insulation the does not fall will continue to hold moisture between the floor joist which can cause an increase in the moisture content of the floor joist itself, leading to possible mold growth or wood rot.
Fiberglass Insulation On The Foundation Walls - This is another common method used for crawl space insulation. Again, the problem with this method is moisture. If your crawl space is below grade, as most are, than the fiberglass insulation on your foundation walls will usually have direct contact with moisture. This is because crawl space foundation walls are porous and tend to allow water seepage. This moisture seeping in through your foundation walls will be absorbed by the fiberglass insulation. Again, this causes the insulation to lose it's R value and become heavy and fall. Fiberglass insulation will also wick moisture, allowing the moisture to move up into the structural wood components that the insulation is usually attached to. This increases the chance for mold growth or wood rot.
Cellulose Insulation on Foundation Walls - Blown in cellulose insulation installed on your crawl space foundation is something I find very hard to ever recommend anyone doing. Cellulose insulation is primarily made up of paper fibers. To avoid moisture saturation it's recommend that this type of insulation be kept approx. 12" above the dirt crawl space floor when installing it on your foundation. But this doesn't address the moisture seepage that comes through your foundation walls. Again, this type of insulation will absorb moisture, become heavy, and fall. Once it has fallen, it will absorb moisture from the dirt crawl space floor, causing possible mold growth.
Spray Foam Insulation - This type of insulation in a crawl space in seen mostly on foundation walls. It can be a great help with increasing energy efficiency. Spray foam insulation in your crawl space becomes a problem when it is installed around the structural wood components above your foundation wall. Any moisture that makes its way into the structural wood components from the outside is now encapsulated with the wood because of the spray foam. This increases the rate at which the wood will rot or grow mold.
Insulating your crawl space can have many useful benefits. But other factors should be considered before installing insulation in your crawl space. The most effective way to get all the benefits of insulation in your crawl space is to have a dry, sealed, moisture free crawl space.