What is the best way to insulate underneath the subfloor of my home?
In most circumstances, the best way to prevent moisture from entering your home through the sub-floor and to insulate effectively is to have half pound, open-cell foam insulation installed at the sub-floor. Because this foam is an air barrier, the moisture-laden air of southeast Louisiana cannot move through the insulation to bring heat and humidity into the home. Also, the foam insulation will not fall out or become home to small animals that might like to live in other types of insulation.
What is the best type of insulation to use in my walls and attic?
The best insulation to use in a hot humid climate like the one in southeast Louisiana is open cell spray-in foam insulation. This foam seals all air leaks and insulates very well in the walls and at the roofline. Unlike other insulations, it is an air barrier, so air infiltration is greatly reduced when using spray foam insulation. Creating an un-vented attic, using foam insulation at the roof rafters instead of the ceiling joists, will offer the most energy benefits. This turns the attic into conditioned space, part of the building’s thermal envelope. When this happens, the HVAC system no longer has to compete with the extreme temperatures found in vented attics, because most un-vented attics remain within 10 degrees of the home’s living space temperature. This allows you to downsize your HVAC equipment, saving money on the front end (by buying smaller equipment) and saving money every time the machine runs (because it is a smaller unit, using less energy). While spray foam insulation costs more than other insulations, its performance far surpasses that of any other insulation.
What is the difference between open and closed cell foam insulation?
Open cell foam is usually more suitable for residential applications for several reasons. Open cell foam is more flexible than closed cell foam. When the framing members expand and contract with the weather, open cell foam will flex with the wood, but closed cell foam will get hairline cracks where it was connected to the framing members because it is not able to flex. Another difference between open and closed cell foam is that, when used at the roof rafters, if a roof leak develops, the closed cell foam will not allow the water to weep through the foam because it is a vapor barrier. This can lead to rotting of the roof deck before the roof leak is ever discovered. Open cell foam is not a vapor barrier, so it allows the water from the roof leak to weep through the foam to the space below. After the roof leak is repaired, the open cell foam can be allowed to dry and its thermal properties return, unlike other insulations that must be replace when they get wet. In addition to these differences between open and closed cell foam, open cell foam is usually less expensive than closed cell foam.
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