Crawlspace Insulation
A very common question in the repair process is; what is the right way to insulate my crawl space? This is a complicated issue and does not have a simple answer. What makes matters worse is the amount of readily available wrong and misleading information on the internet.
There are three areas that can be insulated, but not all three should be insulated. The three areas are:
The floor joist area, or the crawl space ceiling, is the most commonly insulated area. This area is usually insulated with fiberglass and held in place with metal wire or staples. The fiberglass insulation in nearly half of the homes that have insulation in this area has it installed wrong. The fiberglass insulation should be installed with the paper vapor barrier on the heated or conditioned side of the space. This means the paper should be closest to the floor boards and not exposed to the crawl space. Until 2003 insulating your floor joist was the only option if you wanted to have any hope of keeping the winter air from entering your home. Today there is a better and more efficient way to make your home more comfortable and energy efficient.
The rim joist area is the part of the wood structure under your floor. Like the floor joists, the rim joist’s job is to help hold up the floor and walls of the home. The rim joist goes around the perimeter, or the rim, of the home and its primary job is to support the exterior walls as well as giving the floor joist an adjacent surface to be attached. Other names for this area are band joist, sill box and bond.
Insulating the foundation walls is a complete waste of money IF you have an open crawl space. A crawl space with foundation vents that can be opened and closed is considered and open crawl space. It is considered open because the vents, even while closed, offer little protection from the elements outside the home. An open crawlspace with rigid insulation on the foundation walls is like having the walls of your home insulated and opening the windows. It neutralizes the usefulness of the insulation by having the open vents/windows.
When it comes to installing insulation, ask yourself- Am I trying to keep something in or am I trying to keep something out? They seem like the same question, but they’re not. For example, with a vapor barrier you are trying to keep something out, the moisture. With insulation, you are trying to keep something in, your conditioned air. Knowing this helps the process to move forward in the right order. With insulation and a vapor barrier like DrySpace properly installed in your crawl space you can now begin to control the environment under your home. Now your crawl space is part of your home and you should protect it from the outside as such. The days of separating your home from the crawl space is over, mostly because it is impossible to do. It is far more reasonable to accomplish a plan to protect your crawl space from the outside than it is to protect your home from the crawl space and the outside.
So the recipe goes like this:
1Close foundation vents permanently with a cement block
2Install rigid foam insulation on the foundation walls
3Install R-19 fiberglass in the rim (band) joist area
4Install DrySpace vapor barrier on the floor and walls
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The Crawlspace Company, LLC
160 Sir Oliver Road
Norfolk, Virginia 23505
Tel: (757) 362-2300
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Make-up Air
Do you know what make-up air is? When we talk about make-up air in a home, we are describing the air that must enter the home when air is exhausted out of the home.