Attic insulation


  #1  
Old 09-09-14, 10:54 PM
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Attic insulation

This site has always been helpful on my little home projects, so would like to tackle another home improvement with advice from you folks.

I would like to improve my attic insulation. Home built in the 1950s. Now it is insulated between the joists with a brownish wool/cottony type material covered by black paper that has settled into dips between the ceiling joists. 3-1/2 inch roll insulation has been laid out perpendicular across the joists, giving me about 7-ish total inches of insulation.

The home is in northern Wisconsin, where record winter cold temperatures reach 45 below, but it is usually closer to the 0-10 degree range average.

Should I remove all the old insulation and start fresh with batts between the joists and then another blanket of 12-inch bats across that, or can I just lay out a roll of 9 inch batts across what is already there.

I will include a picture of what is there now.

Thanks in advance.

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  #2  
Old 09-10-14, 02:14 AM
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IF you have soffit vents I would advise fitting vent chutes/baffles and then blowing in at least ten inches of cellulose. If no vents I would still advise cellulose.
 
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Old 09-10-14, 05:15 AM
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Yes...I do have soffit vents. Would you blow the cellulose right on top of the insulation already there ore remove the old and start all new?
 
  #4  
Old 09-10-14, 05:16 AM
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Hi igikpak, a couple of extra steps for you.
If the current insulation has not been invaded by rodents (nasty) then it can basically stay. However, a very important step is to air seal the house to attic plane. Doing that will necessitate some digging through the existing insulation and back then the stuff wasn't as user friendly as what we see today, so some removal may be a good idea. I'll add a reference for all kinds of air sealing below.

Note, with air sealing it is the larger leaks that count the most, but as you increase the attic insulation that space will get colder and more prone to condensation from moisture (humidity) in the air that leaks up from below.

I'm not sure what the black paper is, but if it is coated and some form of vapor barrier it should be on the bottom of the insulation stack. On top or in the middle it becomes a condensation layer which is not good. Adding a vapor barrier at the bottom of the insulation may not be practical and if well air sealed a good layer of paint on the ceiling below will minimize any moisture diffusion. Air leakage is 100 times worse than diffusion so get all of the leaks you can.

Over on my side of the northern climate we use a lot of cellulose as Furd suggested. It is dense enough that the cold air in the attic doesn't filter down through it as fast as it does with fiberglass. Fiberglass is really a poor choice for cold attics, despite being used for generations. If you want/need to use a batt insulation, look into Roxul, extremely dense and when installed neatly it will block virtually all air from seeping down to the ceiling plane below.

I'll let you read, but more is better when insulating an attic in your climate.

Bud
http://www.efficiencyvermont.com/ste...ide_062507.pdf
 
  #5  
Old 09-10-14, 05:19 AM
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I just saw your next question, if you remove what is there it makes a much better job and you get easy access for air sealing. Blown in cellulose covers very well.

Bud
 
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Old 09-10-14, 12:16 PM
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Thanks everyone. I really appreciate your comments.
I see now the ceiling joists are 2x6s. The insulation between them is encased in double-faced black paper and stapled to the joists. I doubt these encased insulation rolls are even as thick as the 2X6s. Previous owner then laid 3-4 inch thick batts perpendicular across the joists.

After some more inspecting, I see I have a water leak (with light coming in) through the roof by the chimney. So much for my new shingles installed 2 years ago. Lots of bat poop at the base of the chimney in the attic.

I think I am going to fix the flashing by the chimney first to stop the leak and bats from getting in, remove all the unfaced batts and old double-faced insulation and start from scratch....That way I can seal up any open gaps and holes and I don't have to worry about moisture by having the moisture barrier facing both ways,
 
  #7  
Old 09-10-14, 12:29 PM
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Once everything is removed you will be able to do a great job of air sealing and that will make a big difference. Install the baffles as Furd suggested and get some quotes on having the cellulose blown in. In some cases they can do the job for about the same price as you would pay for materials. And, they will be in and out the same day.

Save some of the lose fiberglass insulation to stuff the ends of each joist bay where the baffle comes down towards the soffit. You want that space closed to prevent cellulose from filling up the soffits.

Bud
 
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Old 09-11-14, 03:37 PM
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Thanks everyone...Much good advice here as I usually find when I post a DIY question.
I am probably going to go with batts as I live in smalltown northern Wisconsin where contractors to do the labor are sparse and stores with the necessary equipment are even sparser.

Thanks again.
 
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Old 09-12-14, 03:33 PM
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One last question, what do you think the odds of this old double-faced insulation having asbestos? Would you have it tested before tearing it out?
 
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Old 09-12-14, 03:55 PM
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The picture doesn't show what is inside or under the black paper so hard to guess. But guessing is not what you need. If you contact a local remediation company maybe they would come out to help identify what is there. If they are honest you will get a more professional opinion.

Vermiculite is the asbestos contaminated insulation I have seen and I've never seen that in a batt or blanket package. Have you opened any of the paper backed insulation, not saying you should if it is asbestos based, but maybe you already have.

Bud
 
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Old 09-12-14, 04:08 PM
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Sounds like what I have been removing from my house. From the same time period as well. Black paper on one side and brown on the other. It appears to be fiberglass to me. Looks like this: https://www.flickr.com/photos/drooplug/8373623801/

Be sure to wear a mask when you remove it. It will be full of dirt and the fiberglass isn't good to breathe.
 
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Old 09-12-14, 05:00 PM
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Yes,
That looks very much like what I have...only the blankets are black on both side...actually it looks like a sleeping bag laying the lengths between the joists since the paper totally encases the insulation. the space between the joists measures 5.4 inch deep but this insulation has sagged so bad it might be only as thick as half that. I have a good breathing mask, that isn't a problem...just don't want to disturb any asbestos, which this probably is not...just want to be sure.
Here is a picture of what i have.....
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  #13  
Old 09-13-14, 03:02 AM
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I forget what that crap is called but it is a chemically treated wood waste product. It was quite popular in the early to mid fifties. I would advise removing it where possible.
 
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Old 09-13-14, 08:59 AM
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Great advice everyone!
One more question on the ceiling joists and insulation.
The "actual" depth measurement of the joists is 5-1/4 inches...
Faced batt insulation at the homestore is 6-1/4 inches thick...
Is that close enough,or do they really make 5-1/4 inch thick rolls and I just haven't looked good enough yet?
 
  #15  
Old 09-13-14, 09:32 AM
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That will work fine. Faced side down and a second layer of unfaced perpendicular across the top. If the second layer is R-30 you are getting close to the recommended amount. If it will be inspected you may need to be sure that total is correct for your zone.

Bud
 
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Old 09-22-14, 11:14 PM
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Thanks everyone.
Just to be safe I sent in a sample of my blanket insulation to a lab...No asbestos...
It came back as 99 percent cellulose and the rest "granular materials."
For $30 and one week wait for the sample report to come back it gave me peace of mind.
Anyway, it was too nice this last week in northern Wisconsin to be cooped up in an attic.
Not a job I am looking forward to doing either...hahaha
 
  #17  
Old 09-23-14, 03:50 AM
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Put a copy of that report in a zip lock bag and nail it to a rafter so anyone in the future who may have the same concerns will find it. Take pictures of your job as well as this type of "going the extra mile" impresses future buyers.

If you don't have a window up there rig up an exhaust pipe for a shop vac to reach all the way to the outside and use a very good face mask. You don't want your lungs to become an air filter.

Bud
 
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Old 09-24-14, 07:00 PM
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Thanks for the advice Bud...hopefully I never have to move again except to the Pearly Gates.
Anyway...I found some insulation with a label...Says it is "Balsam Wool. Completely sealed against moisture."

Anyhow. I already removed the 4" top layer of batt insulation. This afternoon I stapled in the attic rafter vents, then got started on removing the blanket insulation. Got a couple joists worth removed to get a feel for what I am facing then called it a night.

The blankets are stapled into ceiling joists with A LOT of staples.

I think the easy way would be to cut on each side of the joist and roll it up and do the best to minimize dust...Otherwise, removing all the staples could take a long time. How about slitting the blankets and shopvacing up the innards, then tearing out as much of the empty blanket as possible.

Any suggestions. Thanks in advance.
 

Last edited by Igikpak; 09-24-14 at 07:24 PM.
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Old 09-26-14, 03:51 PM
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I went with rolling up the blanket insulation, is coming up quite quick albeit with many protruding staples that will need to be tapped back down.

Quick question...I stapled in roof rafter vents, but there is still a gap between the top plate and roof decking (area above the top plate). Just wondering how to block this area, or if it is okay to leave as is....Can I just stuff batt insulation to block this gap to force most of the soffit intake air up the rafter vents.

Thanks,
 
  #20  
Old 09-26-14, 05:41 PM
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Some rafter vents have a tail on them to block that soffit air, called wind washing. Otherwise, exactly what you suggested is common. Fold a piece of batt insulation and fill the gap. The objective is to keep blown in insulation out of the soffits and get as much r-value directly above that top plate. If you had some Roxul, it comes in a very dense batt and would work well.

Bud
 
 

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