attic insulation (or re-insulation..)

randomlinh

Lifer
Oct 9, 1999
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I've come to the conclusion our attic is a mess, and probably why it's so damn hot upstairs. I've always put off looking at it, but finally bit the bullet. I'm currently in the process of adding insulation baffles so the soffit vents actually take in air (they've been obstructed all this time.. ugh).

In addition, I've notice some of the insulation is paper backed, paper side on the drywall for the ceiling below. But in some parts, it's just loose fiberglass. How should I go about all this.. pull everything out and start from scratch, or just layer more on top? currently, insulation is maybe an inch over the joists. somewhat uneven. It looks more like someone was throwing insulation by the edge of the house to block off the soffit vents :(

In addition to all this, some of the space was plywooded for storage... so there's compressed insulation under that. I want to be able to keep this storage space... is there any recommendation? Should I build up a floor for it so it can actually still have proper insulation underneath? Not that I even know how to really do this... heh

suggestions welcome.
 
Nov 5, 2001
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compressing insulation robs it of it's effectiveness. If you can afford it, I'd remove it all and start over with blown cellulose. It's an easy DIY project and you can rent the machine for free from Lowes and HD if you buy the material from them.
 

randomlinh

Lifer
Oct 9, 1999
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yeah, i understand compressing it is bad.. hence raised floor idea, heh.

I guess that's a possibility. Seems like a huge mess. How much would it cost for say ~600sq ft? is it better than fiberglass?
 
Nov 5, 2001
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I did my whole attic of a 1400sf house and it ran me about $350 if I remember correctly.

it is much easier to do than fiberglas batts, and you can get a better R value without having to layer batts.
 

Greenman

Lifer
Oct 15, 1999
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Don't remove the old stuff, way to much effort for zero return. Just add another layer over the top.
 

Jumpem

Lifer
Sep 21, 2000
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Originally posted by: Greenman
Don't remove the old stuff, way to much effort for zero return. Just add another layer over the top.

I concur. I would just add a layer of blown in insulation over top of everything. It will also fill in the gaps between the rolled insulation and the trusses.
 
Nov 5, 2001
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Originally posted by: Greenman
Don't remove the old stuff, way to much effort for zero return. Just add another layer over the top.

Yeah, I wasn't thinking when I said to remove it, it won't hurt anything.
 

richardycc

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Apr 29, 2001
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I just bought 1000sqft of radiant barrier on ebay for $139 shipped...should lower my attic temperature and my central AC won't have to work as hard, since the air handler is up there.
 

randomlinh

Lifer
Oct 9, 1999
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radiant barrier eh? hrm.

cellulose on top of fiberglass ok? Although, fiberglass might just be easier to deal with to throw on top.

I guess my biggest concern was not all of the insulation was paper back. So no vapor barrier. Granted, the attic hasn't changed much in the 20 some years of the townhome... well, there's some cracking in the drywall in one bedroom.. and one doorway seems to have shifted (a loong time ago).

any comments on using the attic for storage space?
 

cmf21

Senior member
Oct 10, 1999
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Having installed insulation for over 10yrs, mostly cellulose and fiberglass batts, I would just blow another foot or so of cellulose over the top of everything so you'll end up with an r-60 or so. Please don't use blown fiberglass to reinsulate, it sucks, and don't worry about some of the fiberglass not being paper backed, you don't really need it in the attic with enough insulation. Adding baffles was a great idea. Make sure all the vents are blocked either with a baffle or a piece of fiberglass. Their a pain to install but will help the air flow and help prevent ice damning. As for the storage area, I would just leave it alone unless you really want to put more insulation under it. Also make sure you put some insulation over your access holes like old fiberglass batts or something.
 

alkemyst

No Lifer
Feb 13, 2001
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Originally posted by: MikeyIs4Dcats
compressing insulation robs it of it's effectiveness. If you can afford it, I'd remove it all and start over with blown cellulose. It's an easy DIY project and you can rent the machine for free from Lowes and HD if you buy the material from them.

You usually don't remove old insulation but add on top of it. To remove it, it would be a freaking trainwreck.
 

richardycc

Diamond Member
Apr 29, 2001
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Originally posted by: randomlinh
radiant barrier eh? hrm.

cellulose on top of fiberglass ok? Although, fiberglass might just be easier to deal with to throw on top.

I guess my biggest concern was not all of the insulation was paper back. So no vapor barrier. Granted, the attic hasn't changed much in the 20 some years of the townhome... well, there's some cracking in the drywall in one bedroom.. and one doorway seems to have shifted (a loong time ago).

any comments on using the attic for storage space?

you don't want vapor barrier in your attic to trap all the moisture..or you might have mold issue to deal with. the radiant barrier that I got has tiny laser cut holes in them for this exact reason. If you do get the fiberglas batts, you should get the one without the paper for attic use.
 

drnickriviera

Platinum Member
Jan 30, 2001
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You may want to look at spray on radiant barrier. Sherwin Williams has a product called e-barrier. It is sprayed with an airless sprayer to the bottom of the roof decking. They are getting me 5 gallons to try on the house i'm working on. The decking was getting up to 140F, so we'll see what it can do.
 

randomlinh

Lifer
Oct 9, 1999
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Originally posted by: richardycc
Originally posted by: randomlinh
radiant barrier eh? hrm.

cellulose on top of fiberglass ok? Although, fiberglass might just be easier to deal with to throw on top.

I guess my biggest concern was not all of the insulation was paper back. So no vapor barrier. Granted, the attic hasn't changed much in the 20 some years of the townhome... well, there's some cracking in the drywall in one bedroom.. and one doorway seems to have shifted (a loong time ago).

any comments on using the attic for storage space?

you don't want vapor barrier in your attic to trap all the moisture..or you might have mold issue to deal with. the radiant barrier that I got has tiny laser cut holes in them for this exact reason. If you do get the fiberglas batts, you should get the one without the paper for attic use.

well, i was talking more about vapor barrier for the layer flush up against the drywall.. I was under the impression that's what you should do. stuff on top of course would be paper/barrier-less.

cmf21, the storage is just plywood on top of the joists.. maybe 4" of compressed insulation right now. It's maybe 15~20% of the attic space.
 

bobsmith1492

Diamond Member
Feb 21, 2004
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I helped my dad put insulation in his attic. There was nothing up there before. We put down plywood across the rafters to cover everything up and then rolled out strips of regular insulation.

Between that and the foam pads under the siding their heat bill went down quite a bit this winter despite increases in natural gas prices and the particularly frigid winter this year.
 

randomlinh

Lifer
Oct 9, 1999
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Originally posted by: bobsmith1492
Between that and the foam pads under the siding their heat bill went down quite a bit this winter despite increases in natural gas prices and the particularly frigid winter this year.
Yeah, siding is next. One side of the house is hit by 8hrs of direct sunlight a day. The neighbors cut their trees down (roots were starting to move under the house I found out :() so all our shade went away many years ago.

Unfortunately, that's going to be a costly job.. heh. the attic hopefully won't be more than annoying time and maybe a couple hundred bucks.
 

randomlinh

Lifer
Oct 9, 1999
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as a side note, anyone have any issue w/ washing clothing covered in fiberglass.. i've worked in the attic before, but not to this extent. As it stands, I stuff it in a bag for now. Handwash then machine wash separately? Or just toss it out?
 

AlienCraft

Lifer
Nov 23, 2002
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1. Put radiant barrier on roof decking. Either spray on foam or mylar wrapped insulation product. (see #6)

2. Make sure vents are unobstructed and correctly located.
I've seen peak vents and gable end vents placed too far down to allow proper flow. Hot air trapped is not good. Also, be aware of prevailing winds, especially in the evening. A roof vent that is not placed properly to take advantage of that air movement is not working to best efficiency. We have this problem on our roof.

3. Seriously speaking, that compressed fibreglass batt under the storage floor decking is practically useless. Better to pull it out and put a proper batt under there or best idea remove and spray in the high R value expanding foam. That way all voids are filled and that stuff exceeds an R15 3" batt like 3X.

4. Go around edge of roofline and make sure all voids and small cavities are filled with expanding foam.
Any cavities at the edge can induce drafts, these cold spots can form moisture spots, and that can give mold a place to live.

5. Check all flashing and roof jacks around vent stacks, chimneys, satellite dishes, antennas, etc. for integrity and seal.

6. Got an asphalt shingle roof? Been more than 5 years up there? Then it's time to re apply the white granular pebbles that have been blown off over time. These granuals are available in bags and you reapply them like sowing seed over a warm roof. There is also a compound you can apply to get some more "stick" to the roof.
Simply making the surface more reflective via the granuales white color can reduce interior temps.



 

DrPizza

Administrator Elite Member Goat Whisperer
Mar 5, 2001
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Originally posted by: randomlinh
Originally posted by: bobsmith1492
Between that and the foam pads under the siding their heat bill went down quite a bit this winter despite increases in natural gas prices and the particularly frigid winter this year.
Yeah, siding is next. One side of the house is hit by 8hrs of direct sunlight a day. The neighbors cut their trees down (roots were starting to move under the house I found out :() so all our shade went away many years ago.

Unfortunately, that's going to be a costly job.. heh. the attic hopefully won't be more than annoying time and maybe a couple hundred bucks.

Start pricing the materials for doing the siding job - costly to have done for you, but not so costly to do yourself. And, it's pretty easy. The only parts that really require much skill is the ability to use a tape measure, and how you go around doors & windows with trim.
 

AlienCraft

Lifer
Nov 23, 2002
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0
Inspired by the HVAC thread ...check your HVAC ducting for integrity.
You want the insulation to be unbrokenand sealed around the registers and these are prime sources for leaking between spaces. A little attention to detail here can make dramatic changes if there are big , or many small, leaks in the HVAC into the attic.
 

randomlinh

Lifer
Oct 9, 1999
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linh.wordpress.com
Originally posted by: fossilburner
Originally posted by: richardycc
I just bought 1000sqft of radiant barrier on ebay for $139 shipped...should lower my attic temperature and my central AC won't have to work as hard, since the air handler is up there.

how are you installing that radiant barrier?

something like this: http://i23.ebayimg.com/01/i/07/bd/11/f1_1.JPG
isn't that counter intuitive? wouldn't that reflect the heat down at the floor?
 

fossilburner

Member
May 22, 2008
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Originally posted by: randomlinh
Originally posted by: fossilburner
Originally posted by: richardycc
I just bought 1000sqft of radiant barrier on ebay for $139 shipped...should lower my attic temperature and my central AC won't have to work as hard, since the air handler is up there.

how are you installing that radiant barrier?

something like this: http://i23.ebayimg.com/01/i/07/bd/11/f1_1.JPG
isn't that counter intuitive? wouldn't that reflect the heat down at the floor?

or keep heat out from the roof?

I don't know, that is why I am asking.