two insulation questions


Old 01-15-07, 05:35 PM
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two insulation questions

I recently purchased a house. The previous owner placed R-13 fiberglass insulation in the unfinished basement ceiling. Since it was not covered with a vapour barrier or anything else, I removed most of it from the cieling and i am currently storing it on the floor of the basement with a sheet of plastic over it. Is this insulation reuseable when I decide to finish the basement, which will be in about 2 years or should i chuck it. If I have to chuck it, is there a correct way to dispose of fiberglass insulation?

My second question concerns the master bedroom. On cold days the mb room will be 5 degrees F cooler that the rest of the house. The room is above an unheated garage. The cieling and the north wall of the garage are covered with dry wall. The coldest part of the room is floor adjacent to the north wall. Similar houses in the area that have no dry wall on the same wall do not have insulation.

If the cieling of the garage is properly insulated does the north wall have to be insulated? (I have just put a new R-16 door on the garage this past fall - it replaced an old single panel wood door - no noticable difference in temp in the mb room)

if insulation is needed in the garage what is best way to proceed?
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Old 01-17-07, 09:20 PM
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To answer your first question. If the insulation does not get wet and/or dirty, you can re-use it. As far as disposal, fiberglass insulation is not rated as a hazardous material and you can usually just throw it out. But I do suggest you check with your local city officials. Most towns will not accept contractor's debris and they may deem as such unless you let them know otherwise.

For your second question. Insulation does not produce heat, it reduces "Heat Load". Heat Load is influenced by several factors. Such as the average difference in temperature between the inside and outside your home during the winter. Another important factor, and this is key to your situation, is surface area that is affected by the temperature difference.

If we apply this to your situation, the new garage door is a perfect example. Since there is no heat source in the garage, the temperature in the garage will virtually be the same temperature outside. Regardless of the amount or any insulation you have in the garage walls. The definition of "Heat Load" is the amount of heat measured in BTU's per hour needed to replace the heat lost in order to maintain a certain temperature. The amount of heat loss through your bedroom floor into the garage is no where near the amount of BTU's per hour to even raise the temperature of the garage one degree Fahrenheit.

The other aspect of your situation is surface area that is affect by temperature difference. In most cases like yours three walls, the ceiling (attic) and floor (garage) of your bedroom are in direct contact with an unconditioned space. If you compare the surface area of your bedroom exposed to unconditioned spaces to other rooms in your home, you will see that the surface area in your bedroom is more than double. Therefore, your Heat Load for your bedroom is more than double than the other rooms in your home. A five to ten degree difference between your bedroom and the rest of the house is not unusual.

My advice would be to pose your situation in the "Heating and Cooling" forums. They will advise you on how to increase the amount of heat to this bedroom to compensate for the Heat Load.
Old 01-19-07, 07:45 PM
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Head's up...

"As far as disposal, fiberglass insulation is not rated as a hazardous material and you can usually just throw it out."

Other places may be following suit, so a head's up on this...

Here it is treated the same as hazardous waste (because it is classified as a carcinogen). It requires double bagging for disposal.
Old 01-19-07, 08:12 PM
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crawl space

The comment that energy usage is dictated by the temp difference from interior to exterior is not the whole story.

Actually what determines t your energy usage is the temperature of the dry wall. Ex. Ceiling temps with FG on a 95 deg day can reach 110 degs or more. Drywall radiates 90% + of this energy. If you have a 75 deg floor temp the ceil'g will radiate about 37 btu/hr/sf. Multiply this times your sq footage. This is why a/c costs are so high. This is also why little old ladies die in FG homes in summer. Heating mode too.

Depending on the type of radiant barrier installtion the dry wall will radiate about 2-6 byu/hr/sf.

Ck the thread, FG or radiant barrier in crawl space.

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