Foam insulation is very expensive but it usually offers the highest R-value. It is usually installed by a professional as it requires special equipment to meter, mix, and spray the foam into place.
Polyicynene is one of the materials used in foam insulation and it is considered an open-celled foam. An open-celled foam insulation material is not compressed. As such it traps vapor barriers or air within the cell. The advantages of open-cell foam are it’s cheaper compared to closed-cell foam and it can easily be taken off. The disadvantages would be that open-celled foam insulation is less resistance to moisture and should not be used in area where moisture is a concern. In addition, as there is air trapped within the cells, open-celled foams usually have a lower R-value for a given thickness compared to closed-cell foams. Open-cell-foam insulation is usually used to protect items in shipping.
On the other hand, polyisocyanurate and polyurethane are closed-cell foams. As the name implies, close-celled foam is the opposite of open-celled foam. After applying the foam to an area, as the foam cures, it forms bubbles or tiny cells that have solid un-broken cell walls, making this insulating material harder and resistance to moisture. Closed-celled foam also provides more R-value per inch than open-cell foams and is the product of choice if the insulation is likely to be exposed to high moisture or to water.
Foam insulation is usually applied in irregularly shaped areas where cutting fiberglass batts would be labor intensive. Other than that, foam insulation is also used in insulating hard-to-access building areas – a spray wand can be inserted into tight spaces to release the expanding foam product which will expand to fill the odd-shaped space. It also provides a very good air leakage seal as well as it is wind leakage and moisture (in the case of close-celled foam) resistance.
Rigid insulation is a broad term used on a variety of insulation. The foam insulation which we discussed earlier can also be considered as a type of rigid insulation after it hardens. In general, rigid insulation is tough and long lasting and is usually used in areas such as the roof where it gets the most exposure from the environment. Rigid insulation is made from fibrous materials or plastic foams and is produced in board-like forms and molded pipe coverings. Rigid insulation is very effective in providing full insulation coverage with minimum heat loss and is often able to provide a greater R-value where space is limited. Rigid insulation in the form of board is sometimes fitted with a reflective foil that reduces heat flow when it is installed next to an air space. Rigid insulation is often used for foundations, roof and as an insulating wall sheathing.
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