Opinions when replacing attic insulation

Old 10-10-19, 03:09 PM
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Opinions when replacing attic insulation

Hello everyone,

Just looking for opinions on insulation for my attic. Our current insulation is very old and probably the original. Itís about 50+ years old. In the winter, the bedrooms upstairs are always colder than downstairs. And in the summer, those bedrooms are hotter upstairs than the downstairs. We have forced hot air for our heat.

Our kitchen also sticks out from the back of the house, and there is a small roof that sticks out about a foot over the kitchen. Both this roof, and the main roof above it, both had ice damning last year and water came in through the soffit of our kitchen. Iím thinking if I replace the insulation, it may help the situation.

Iíve received three estimates from three companies and once again, Iím shocked to see that they have three different techniques to offer.

The first company said they would remove the fiberglass insulation from the floor, and put spray closed-cell insulation on the two walls and the entire ceiling of the attic. The ridgeline vent and the two gable vents would be sealed over. That cost was over $10,000.

The second contractor (small mom and pop type) said he would leave the fiberglass insulation on the floor, and spray closed-cell insulation on the attic ceiling. He was about $2300.

The third contractor said he would just simply remove the fiberglass insulation from the floor, perform air sealing, and put in new R30 fiberglass insulation. He did not recommend putting anything on the attic ceiling. He said he could also do blown in insulation (not cellulose) on the attic floor instead, but he said the R-value is basically the same as the fiberglass insulation so there isnít much benefit. He said that job would be about $200 to $300 cheaper than the fiberglass batting.

So arg, Iím confused. Any opinions?

Old 10-10-19, 04:07 PM
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I'll leave insulations options to others, but I have two comments. First, place effort on properly sealing the attic closing up any places where heat could escape from the living area. Insulation does not stop airflow, so proper sealing could go a long way toward increasing the benefit of insulation.

Second, making certain ductwork is properly insulated and sealed, as well. Heat loss from ducts could be substantial.

Consider getting yourself an infrared thermometer, then go into the attic and look for areas of heat less.
Old 10-11-19, 03:14 AM
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and spray closed-cell insulation on the attic ceiling
You never insulate under the roof of a house, I can't believe someone suggested that!

As noted the air sealing is a critical component of a well insulated house.

There is no reason to remove the old insulation, it doesn't wear out! Adding additional cellulose or chopped fiberglass is the most efficient!
Old 10-11-19, 04:05 AM
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Your attic sounds like it is more complicated than just an open area.
I cannot visualize the kitchen roof and the two walls one person was going to insulate.

You my also have a ventilation problem as you did not mention any soffit venting.

Have you ever taken a look up there in the winter.
Assuming that you live in an area where it gets below freezing, if you see frost on the rafters etc then you have major air leakage. Often it ends up being mold.

Getting rid of ice dams involves insulation value, sealing the attic floor and attic ventilation.
Old 10-11-19, 12:32 PM
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Spray foam on the inside of the roof can be one of the best ways to insulate a home, also the most expensive. But you have to know what you are doing. A lot to consider. I have been researching conditioned attic spaces, which is what you have when you spray foam the underside of the roof, and it is appealing but it looks like I would need to replace my furnace to make it work properly, which we just replaced 5 years ago. I have a atmospheric combustion furnace and that causes problems with venting it. I will probable be air sealing the floor of the attic completely and using blown in insulation. The thing to remember is air sealing is the most important part. even more important than how many inches of insulation you have. The best way to air seal is to remove all of the old insulation so you can get to every crack and crevice with spray foam and seal it up. Air flow through batts or blown in insulation reduce the r value drastically.


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