Attic Insulation

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Old 12-12-19, 08:13 AM
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Attic Insulation

Hello,

My DIY is just doing research before I hire contractor to apply new insulation in my attic! I have 2 estimates. One contractor wants to use Blown in Cellulose, and other contractor wants to use blown in Mineral Wool.
Does anyone know which is the preferred material to use?

Thx for any advice.

Ednort
 
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Old 12-12-19, 08:44 AM
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There are lots of options, fiberglass, cellulose, and rock wool, they all work!

Doing it myself I use cellulose only because I hate working with fiberglass, if having a company install Id go with the cheapest per R value!
 
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Old 12-12-19, 09:06 AM
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If you have soffit vents be sure that the quotes include ventilation baffles otherwise they will likely blow in the insulation and block your soffit vents.
 
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Old 12-12-19, 09:29 AM
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Thanks, I know how important that is. Turns out one contractor stated addressing that in estimate while other one didn't mention it! Stupid question, is there any easy way to notice if I do have soffit vents? My attic is hard to maneuver in, and there is quite a bit of old insulation up there.
 
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Old 12-12-19, 09:33 AM
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Typ they are the cardboard or foam channels, about 4' long, that are installed on the underside of the roof deck, between joist/rafters and they extend down through the insulation to the soffits.

Should be easy to see if they exist!
 
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Old 12-12-19, 10:56 AM
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It does not look like any baffles are installed. My home was built in the mid '60s. Maybe they didn't install those because they wanted to save on costs. And I thought my house was well built.
 
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Old 12-12-19, 12:05 PM
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Or it could be that you dont have enough insulation currently that requires them!

But with the new insulation it's the right time to add, you dont want to block off the air flow with the new insulation!
 
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Old 12-12-19, 03:05 PM
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Hi Ed, before the new insulation goes in you will have your best opportunity to do some air sealing between house and attic. You probably won't be able to get it all but there are major air paths that are well worth your attention. Some insulation companies do that work as well and can give you a quote.

What do you see from the outside looking up at those soffits and what do you have for high ventilation?

Bud
 
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Old 12-12-19, 04:51 PM
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Hi Bud,

Luckly, both contractors I received quotes from, already said they seal before installing the insulation. Makes you wonder why this was not done back in the '60s when this place was built, or at least when the original owners had insulation added, who knows when! I guess very few houses had this sealing done back then.

As far as soffits, above the second floor, looking outside, on one side, and at the front of the house is constructed with overhang soffit, There are 3 sections of what looks like air grills spaced equally apart. There is a fan on the roof which i don't use, and large vents grills (no Fans) on both sides of attic that are located at both ends.

Thx for any more info!
 
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Old 12-12-19, 05:07 PM
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In the 60's we bought gas for $0.16 a gallon on main st in Bangor. At that price no one was concerned about using extra energy and back then air leakage was not on the list of building practices.

Did either company mention taking a before and after blower door air leakage measurement? Testing before and after is how you know they made an improvement. In addition, you want that after measurement for other purposes, like fresh air needs.

In any case, whatever they do will be better than doing nothing.

Be sure they add baffles to all rafter bays even if only a few have vents below. At some point you may want to add more vents.

Bud
 
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