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Spray Foam Insulation - Is it Really that Good?
Spray foam insulation has become one of the hottest insulation products on the market since the late 1990s. Although this spray application has existed since the 70's, it was not as popular because of the large amounts of formaldehyde in the insulation material. Today there is no formaldehyde, the R-value per inch is at least as good as any other products, and it has the best air sealing abilities of any insulation product currently available. So why isn't everyone insulating with spray foam now? The answer to this is complicated, and so are the choices of spray foam out there.
Closed cell polyurethane spray foam insulation
That's a mouth full in itself. This type of spray foam is considered the best because the multiple cells that make up the foam are encapsulated onto themselves. In other words, they are virtually impentrable to moisture, taking care of any mold worries.
The word "polyurethane" is a fancy way of saying "plastic." So this insulation material is simple a 2 part plastic that when heat is applied and sprayed on a wall or ceiling (or anything), it expands to roughly 50% of it's original size.
There are many varieties of spray foam densities and each density has a slightly different R-value. Most of the spray foam that is used in temperate climates that see great deals of temperature and moisture fluctuation is 2 lb density foam which has an aged R-value of R-6 per inch. The reason there is an aged R-value is because there is a small amount of off gassing that occursas the foam ages. Non of the gases are toxic or hazardous in any way, but they do effect the R-value slightly. For instance, the initial sprayed R-value of 2 lb foam is R-8 per inch. Please note that there is only a small amount of R-value lost, and it has very little effect, if any, on the performance of the insulation. Also, there is no vapor barrier needed with closed cell foam because of it's water resistent and air sealing quailities. Anything under 1.5 lb foam is NOT considered closed cell anymore and is now considered open cell foam... which we will get to in a minute.
The major benefits of closed cell foam are numerous. For one, you only need 3 inches in a wall and 5 inches on the ceiling to meet all your code R-values. When using this product, your building is airtight. The only air that comes in is the air you want to come in making your building extremely efficient; from 30-50% more efficient than fiberglass and 10-25% more efficient than wall spray or dense pack cellulose. Now before you go running to the phone, there are of course some major drawbacks. The first is price. It is very expensive at around $4.00 per square foot. It is not uncommon to have a price tag of $13,000 or more for an average house of 1500 square feet with 8 foot ceilings. Generally you see your savings within 5-7 years or less depending on your lifestyle.
Open cell polyurethane spray foam insulation
This type of spray foam is marketed the hardest by a company called Icynene. Icynene has several foam and spray applied products, but there biggest seller is open cell spray foam insulation. Why? It is significantly cheaper than closed cell spray foam and offers the same great air sealing abilities. There are, however, several key differences.
Open cell spray foam insulation is still just plastic that is heated up as it is sprayed in on a wall or ceiling. The difference is because the foam is less stable, it has an aged R-value of R-3.5 per inch, and fills the cavity completely in order to reach code requirements. Because the cells are open, the foam acts and feels like a sponge. There needs to be a spray or brush on vapor barrier applied to the spray foam once the foam has curred (curring takes about 10-20 minutes) in order to prevent moisture absorbtion.
Open cell spray foam is approximately half to three quarters of the price of closed cell foam. It remains popular for this reason. When applied correctly, the energy savings are just as good as closed cell foam.
Pour in Place polyurethane foam insulation
This method of foam insulation started around the 70's also, but never took off until recently. This is currently the most common way to insulate the cores of concrete block walls. It can be used on residential homes as well, existing or new.
This type of foam is a bit different from the others in that is isn't so much heat based for expansion as it is water and pressure based. The foam is roughly about $1 per square foot and offers comperable air sealing qualities to spray applied foams. This is considered a low density .8 - 1 lb foam and is open cell.
One of the main complaints of this type of foam has been shrinkage. It tends to shrink away from the studs if the water and pressure mixture is not correct and I have been told by other contractors that it takes a lot of monitoring to keep the proper consistency. As for any blind use application with any product some inconsistencies are to be expected.
So Which foam do you choose?
When choosing any insulation product you have to consider the cost, the amount of energy savings, and how long you will be in the property to recoupe those savings. One thing that has raised property values in this bleak economy have been energy efficiency improvements, so that is a factor as well.
All spray foam applications should be performed by a professional. They do sell kits for do-it-yourselfers, but they are tempermental and if you do not know what you are doing, you will waste a lot of money. These kits are about $400 for 200 board feet and $800 for 600 board feet.
Always remember that if you do not know what energy efficent upgrades to do, hire an energy consultant. He/she will go through the building with you, test the entire property for efficiency and give you a report of areas to improve upon. Depending on the state you live in, you may be eligible for some rebates.
For more information on insulation and heating efficiency, click here.