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Adding attic insulation


vincent's Avatar
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SC

11-16-17, 09:10 PM   #1  
Adding attic insulation

Hello everyone
I read an article on another site (TOH) about adding attic insulation. It said it was ok to lay down unfaced batts perpendicular to the ceiling joists on top of the blown in that's already there, which is what I have.

I have 6 inches of blown in cellulose and was thinking of adding r-21 batts across the attic to get my power bill down.

What about the HVAC ductwork that's running all around up there. It's already insulated but it's tight to the framing, so I won't be able to get any underneath. Just leave those alone????

Any other suggestions will be greatly appreciated as well. Thank you.

 
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XSleeper's Avatar
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11-17-17, 01:50 AM   #2  
About all you can do is cut around it, fitting the insulation as tightly as possible against any obstructions so that there are no voids.

If you want to add more insulation and you have blown in cellulose, what's the reason you don't just get more cellulose?

 
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11-17-17, 02:33 AM   #3  
Think about all the fun you will have hauling up all the batts of insulation, crawling around the attic trying not to step in the wrong spot vs getting up there with a hose and spraying more cellulose. Plus the fun of handling all that nasty fiberglass.

Granted the cellulose involves some work, it's dirty, but soooo much easier that trying to roll out fiberglass.

 
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11-17-17, 04:25 AM   #4  
Why do you think that more insulation is needed?

 
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11-17-17, 04:52 AM   #5  
I would blow in more insulation, cellulose or fiberglass. Most home centers have a blowing machine you can use for free when you buy their insulation. Or, in my area it is about the same price to have an insulation professional do the job. The blown insulation will go tight up against all the duct's and may form a better seal than you could get with batts.

 
vincent's Avatar
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11-17-17, 08:23 AM   #6  
Thanks for the feedback. it's a 40 year old house in SC, the blown in is six inches max, which calculates to R-18 according to the this old house page, which also says it should be r-38 in my area. And the power co sends out a sheet that compares houses in the area, and mine is higher than average. They are scheduled to do an audit for me, but it seemed obvious more insulation would help.

I also thought blown in would be a professional job and cost more, although I didn't get that far figuring all this out yet. So I will.

Hauling batts up to the attic ain't no big deal for me. I'm only 62.......

 
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11-17-17, 08:58 AM   #7  
Blowing insulation is easily a diy project as long as you have a helper. You go up there once, blow the insulation, and come down when you're done.

It's good if you can both have a cell phone to communicate when you want it on or off... or when you need to pause.

 
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11-17-17, 11:28 AM   #8  
It's good if you can both have a cell phone to communicate when you want it on or off.
The machines I have used had switches in the hose but the phone would still be a good idea to have that beer ready since it can be a hot dirty job.

Don't forget the respirator , goggles and sufficient light.

Another item that I noticed at my current house when they installed the ceiling insulation. The had "rulers' sticking up throughout the attic, would help keep the insulation even across the entire area.

 
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11-17-17, 11:58 AM   #9  
Blown in insulation is relatively cheap. I had 16" added to my attic for $350. Have you seen the prices on batts lately? Crazy. Curiously, I didn't see much savings on my electric bill. It was a bit cooler upstairs in the summer, but not as much as I expected. How old are your windows? Replacing all of my windows made a huge difference. I want to say at least a 35% reduction in my bill. A new HVAC system also made a world of difference.

 
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