Insulation over garage


Old 11-14-01, 01:30 PM
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Question Insulation over garage

I finished the room over my finished, insulated garage last summer and the room in the winter gets colder than the rest of the house. I insulated the room with the appropriate R value insulation in the rafters and the studs. Is there anything that I can do to heat up the room short of installing another temperture zone? I understand that because it is over the garage, I might be out of luck, but I thought I would see if anyone has any suggestions.
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Old 11-14-01, 01:54 PM
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Greetings, Cjrb138

You have two problems that are causing this condition.

You have a heat flow area, down, equal to the ceil'g area so that greatly increases the energy requirements. You can actually lose more heat to the garage than thru the ceil,g.

Second, you are a victim of the "R" value scandal. Bulk insulations such as fiber glass are tested to a C-236 test standard imposed on the whole insulation industry by the fiberglass industry. This test is practically worthless because the temp difference is only 30 degrees (60-90 deg). It is a short duration test that minimize the radiant energy effects and is as humidity free as possible. I have had a standing offer to any home owner or buiding contractor, that if they can provide me with valid test results from a government certified, independent lab, that fiber glass gets the advertised "R" values during summer/winter installed conditions test, I wil insulate their home or next job free of charge, labor and material. No one has come forward in the past 29 years.

In house tests by a major fiberglass manufacturer, about 30 years ago, in a brick veneer 2x4 wall construction, showed a "R" value loss of about 50%. Thats why your room is so cold.

You can help the situation considerably by installing a radiant barrier in the garage ceiling and over the attic insulation and painting the walls will a radiant barrier paint.

If you want details, let me know.

Thank you for considering my opinion.
Old 11-14-01, 03:19 PM
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Thank you for the responce. One question: What is a radiant barrrier and where can I buy one?
Old 11-15-01, 07:13 AM
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Greetings, Cjrb

Radiant barriers(RB) are sheets of paper or plastic film with aluminum foil laminated to both sides. They are rated at 97 % efficent. Glass is less than 10%. You can find info on the web, enter www. or in your search engine enter "radiant barrier" or "reflective insulation". RBs are use on space ships. survival blankets for fire storms or sub zero conditions.

If you do not have dry wall in the garage ceil'g then your installation will be more effective because you can insulate the joists with 2 layers of RB and the rim board between the joists and along the sides. If not, then you can attach the RB to the surface of the garage ceil'g with staples and then 1x2 on the joist line and install new drywall.

In the ceil'g you can install a RB over the existing insulation. I would have to know your location so that I can tell you the best method. The RB will save you considerably on a/c costs and also help with the winter costs too.

For the walls check for RB paint. This paint is 30-40% efficent and is painted on the inside of the exterior walls. However, it has to be a light color. It is about 3-4 times more efficient than the fiberglass.

If you cannot find a supply of RB in your area, I can supply the materials you need.

If you like what you see on the web and want to continue, let me know.

Thank you for considering my opinion.
Old 11-28-01, 06:17 AM
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Smile More information please

You don't describe your location, the type of heating system you have, whether or not the garage is heated or if there is any insulation in the floor.

Users of this forum, (or any other information source for that matter) have to be very carefull of the information they receive. The information that rbisys is giving has some merit, but is a very small part of the whole picture. It is irresponsible to be flogging a product before all the facts are known.
"You are a victim of the "R" value scandal."???? LOL
Insulation is a very simple product. I provides a resistance to heat flow. The more you have, the slower the heat transfer. No matter what numbers you use to describe its effectiveness, the principle is still the same. More insulation - slower heat transfer.
Radiant barriers and other such products can provide a tremendous benefit, but should be viewed as an enhancement rather than a neccesity.
Old 11-28-01, 05:41 PM
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Greetins, Greg H

I have been selling and installing RBs for about 30 years, belive me they are more than an enhancement.

In the St. louis area I have noticed that fiber glass homes use about 40% more winter energy and about 200% more a/c energy than a RB home. Your comments indicate that you have no direct operational knowledge of RBs.

The "R" value system that you embrace is based on a C-236 test that is about meaningles when exposed to the light of day. It is a very limited test that minimizes the radiant energy effects and is done bone dry. Your experience should have revealed to you that bulk insulations such as fiberglass and cellulose condensate and absorb or suspend enough moisture to reduce the "R" values by up tp 50% or more. SEE ASHRE

Try to get an installed winter/summer test (Delta t 70 - 100 exterior degs vs 0 - 75 deg interior and see what you get) with moisture and radiant energy effects. (Even from the government, DOE)

I'm sorry to inform you that you are the victim of the "R" value scandel. If you check an engineering hand book, emissity chart, you'll see that glass and wood are about 10% efficent, petroleum products (foam) about 20% and aluminum foil 97%. To put this in perspective going from "R" 19 to "R" 38 with fiberbglass will probably never pay for itself in energy savings. Also, some evaluations have shown that too much bulk insulation can actually increase a/c costs. This is because of the increase in material mass and additional moisture present. As you know, moisture is an excellent retainer of heat enery which is released when the sun goes down. RBs do not have this problem and react instantly to the energy load on them or removed from them. Installing a RB over "R" 19 or 30 will probably save you up to 30% in a/c costs. If you ever have the opportunity to evaluate a RB house or business you'll see what I mean.

Heat'g/ cool'g salesmen do not like RBs because they have to down size the equipmet so much. Also they usually sell insulation as part of the package and they promote the more is better ploy.

Please be sure you know your subject before challenging me.

Thank you for considering my opinion.
Old 11-28-01, 08:39 PM
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My apologies!

I am very sorry that you feel challenged. My intent was to encourage the poster to get all the facts before making a decision on serious changes to his home.
I have looked into RB and agree with you that it will greatly reduce radiant heat transfer, but as we all know there are three types of heat transfer. Conduction, convection AND radiation. Your product does not address all three.
I do not wish to discredit what you are saying, but think it should be put in perspective, and be seen as a part of a system. When you say that fibreglass can loose up to 50% of its insulation value when wet is absolutely true. What you have not mentioned is that for this to occur you must also have a faulty installation. No product will work if improperly installed, even RB.

The US Gov't has RB information on The Dept of Energy site.

A couple of quotes from their site.

"It may also be worth noting that a very glossy white paint is within10% of as good reflector of heat as most of the common radiant barriers currently available in residential construction."

"Two field tests, one in Minnesota and one in Canada, both found that a radiant barrier placed over R-19 attic floor insulation (which is less than half the DOE minimum recommendation for those climates,) found that the radiant barrier contributed to less than a 1% reduction in energy consumption for heating and cooling."
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