Foam Insulation


Old 09-25-03, 09:41 AM
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Cool Foam Insulation


I have been looking into having the underside of my roof sprayed with foam insulation. The contractor will apply 4" with an R value of 21 ( he says this is equal to R 60 in fiberglass insulation due to the sealing qualities of this product) and 40 % savings on heating bills that were $2300 last year. Cost $1.70 per sq. ft. installed about $3800.

Your expertise will be most appreciated.

thanks fstedy
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Old 09-25-03, 07:49 PM
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"If it sounds too good to be true, it probably is."

In reality, the R value of 21 is equal to the R value of 21.

As a general rule, attic insulation in applied to the floor of the attic. Adding insulation approaches diminishing returns beyond a certain point. For instance, needing R39 in your attic might not be worth the cost of adding insulation if you already have R30. You might never see a reasonable return on your investment.

There is a lot of hype out there for many things for which there are no studies, no science, and no proof.

It is more prudent to have a heat load and heating loss study done on your house to find out what the load is and where heat is being lost. From that, you can formulate a plan for what action to take, then get at least three bids for the work with three references for each.

Ask your heating energy supplier what the typical cost is for heating up there. It may be that $2300 is not out of line for that far north.

Hope this helps.
Old 09-25-03, 10:08 PM
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I agree with chfite, it does sound too good to be true. First of all you have to subtract your base usage, such as water heating, cooking and drying and subtract that from your gross annual energy bill. So let's assume all this comes out to $25. per month, which comes out to $300. per year. You subtract that from your annual bill, which produces your annual heating cost. I know this is a very conservative number, but I am only using it as an example.

This also applies to other things that contribute to your energy bills. For example, let's assume you have your system serviced and it acquires a 10% savings from being more efficient, which is not unusual. You subtract this from you annual heating bill and this so called 40% saving begins to dwindle. Other actions that produce similar results such as duct cleaning, which reduces surface tension improves efficiency, vacuuming baseboards that increase heat exchange increases efficiency and so on.

The 40% saving is far fetched in my opinion and utterly ridiculous if insulation already exist in the home. The next problem I have with these types of statements is that you do not have anything to compare your heating cost to. For all you know, for your size house, you bill may be low. In doing heat load/gain calculations, guess what? I made mistakes, I omitted a room or added one twice. The NJ Dept. of Energy has a default equation for heating and cooling. I use it as a check, meaning to say if my calculations differ too much from the default calculation, I recheck my calculation to see if I missed anything.

The NJDOE default equation for your area is $835. per year for a 1600 square foot house. So let's say your house is 30 feet by 40 feet and is two stories. So the square footage for your house is 30 times 40 = 1200 times 2 stories = 2400 square feet.

To apply the default is 2400 divided by 1600 = 1.5 times $835 = $1252.50 the annual cost for gas for an average home this size in the State of NJ. This based on over three decades of statistics. Also you have to consider what is considered average in NJ. That is the average home has insulation. What is nice about the default is that it gives you a target. For example if your home is already insulated and your heating bill is much larger than the default, then something is wrong in your home. Like you may have to have your system serviced, distribution system cleaned or something as simple as sealing the pull down folding stairs because it doesn't close properly. Or checking to make sure all your windows are closed, a lot of times the top sash is open and the heat from the house escapes through them.

On the other hand let's say there is no insulation in the house, then insulating your attic and walls the default gives you an idea what you might be paying afterwards. Not exactly because there are a lot of variables, but close to it.

I have dealt with high energy bill for over a decade in this State. I know this is a difficult subject for the average person to comprehend. What I am basically saying is that adding insulation does not solve problems in the home that contribute to the high energy bills. So stating that you will save 40% on your energy bill by adding insulation is erroneous.

What amazes me is that people will get a tune-up for the car when it is not running right. They notice the difference immediately in how the car performs and soon afterwards they realize that they get more miles per tankfull. This same principle applies to your home. Yet people will go years before they have their heating system serviced. Walk aroung your home, check your windows, look to see if the attic door closes tight, clean your baseboards, radiators or vents periodically. Make sure the damper on your bathroom exhaust fan works. Then take this $3800. and put it in a fund for your children's education.
Old 09-26-03, 01:26 AM
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foam insulation

Chfite and Resercom

Thanks for the info it certainly gives me something to think about. My home is about 2400 sq. ft. with a boiler, radiators and window air conditioners I am thinking about replacing my system with a hot air furnace with central air. Presently there isn't any ducts to run this type of system but my neighbor who has a similar home had a 100,000 btu unit installed in the basement and another 50,000 btu unit in the atic with cooling air handlers on each.

I had foam installed in my outside walls about 25 years ago and new double pane replacement windows that are 15 years old. The atic has only loose insulation from about 50 0r 60 years ago and I think this is where my heat loss is. Also the parallel feed pipes in the unheated basement are 3" in diameter and uninsulated.

thanks fstedy
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