If your thermostat is set high and your floors are still cold, there’s a good chance your crawl space is the culprit.

As part of an overall insulation system, crawl space insulation plays a crucial role in maintaining the energy efficiency and comfort of your home.

If your house does not have any insulation on your crawl space walls or in the band board area, you would be wise to install a spray foam from the floor of the house down to the plastic vapor barrier.

Benefits of Insulating Your Crawl Space

There are many benefits to properly insulating your crawl space:

  • Over time, you’ll recoup over and above the costs of insulation by saving money you otherwise would have spent to keep your furnace running.
  • When combined with the rest of your insulation system, effective crawl space insulation keeps outside air infiltration at a minimum, meaning your heating and cooling equipment does not have to operate as hard.
  • Allergens and other irritants will have much more difficulty getting into your ventilation systems, ensuring the air in your home is as clean as possible.

Insulating Your Crawl Space

There are two general classes of crawl spaces: ventilated and unventilated.

The first step in either a ventilated or unventilated crawl space is eliminating sources of water and installing an effective vapor barrier.

First, let’s address the ventilated crawl space. This type of crawl space is used when you want to isolate the living space from the crawl space. For example, when your crawl space is very deep or when there is no ductwork, or if there is unmanageable moisture in your crawl space.

In a vented crawl space you want to use an effective insulation directly to the floor of the house, such as spray foam. In a ventilated crawl space, you also need to wrap any heat water lines to prevent them from freezing in the winter.

Second, let’s address the majority of crawl spaces, which should be unventilated. This means that we use an effective insulation such as spray foam on the foundation walls, band board areas, and a continuous vapor barrier on the floor. Finally, we block off all the vents. This allows the living space and crawl space to maintain similar temperatures and humidity levels.

With the ductwork being in the crawl space, now you do not lose the heat that is put off in the heating season and your ductwork will not condensate in the cooling season. This will warm up the floors of the house in the winter and lower your utility bills.

With unventilated crawl spaces, your floors could be 10-20 degrees warmer. Harwood floors, wood trim and cabinetry are more stable in a controlled humidity environment. Since 50% of the air you breathe in the heating season comes from the crawl space or basement areas, it is much healthier to have less humidity (which means no mold) and a mild free zone in the crawl space.

Fiberglass is not an effective insulation here. If air can move through an insulation, fiberglass insulation will not maintain its R-Value at all temperatures. This is a building science law, just like the law of gravity.

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