Posted: 7/4/2010 5:38:15 PM EDT
| We just converted our garage into an extra room (about 400 sq/ft) and I need to get insulation installed in the attic above the new room. Our house was built in 1988. Should I look at having the old original insulation (loose fill) removed and having the whole attic redone, or just have new insulation put in over the new space? I don't mind spending a little extra money if the return on it is worth it, but I don't want to throw money away for nothing. |
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There are a lot of choices out there now from cellulose (treated ground up newspaper) to ground up blue jeans. You can rent a machine and buy the cellulose at Home Depot and do it for a lot less than if you hired someone.
The one thing that blown in insulation does not have is a vapor barrier like bat fiberglass. Under some condition that could cause a moisture problem but I have yet to see that happen. I suspect it would have a lot to do with how well the space is vented. Remember, most heat is gained and lost through the roof if there isn't excessive window space. |
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If it's 1988 you're asbestos free.
You can blow in more on top, or lay batts perpendicular to the joists. Actually, you can lay R13 batts parallel to the joists, and thicker stuff on top of and perpendicular to that. From what I've heard, if you buy a certain amount of blow in insulation at Home Depot, they will loan you the machine for free and you can do it yourself. If you go this route, wear a hooded bunny suit with gloves, also goggles and a respirator. |
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With insulation, it's always best to have a barrier on both sides. Otherwise it will take much more depth of insulation to be as effective. Standard fiberglass insulation with a foil/paper backing works this way when properly installed. However, many contractors install it the other way. It's less effective when the foil is against the drywall and the raw fiberglass is exposed to the attic.
Put another way, you would never wear a winter jacket with the windbreaker on the inside and the insulation on the outside, fully exposed and uncovered. Yet, wear a sweater with a windbreaker over the top and you'll be warm. |
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Quoted:
With insulation, it's always best to have a barrier on both sides. Otherwise it will take much more depth of insulation to be as effective. Standard fiberglass insulation with a foil/paper backing works this way when properly installed. However, many contractors install it the other way. It's less effective when the foil is against the drywall and the raw fiberglass is exposed to the attic. Put another way, you would never wear a winter jacket with the windbreaker on the inside and the insulation on the outside, fully exposed and uncovered. Yet, wear a sweater with a windbreaker over the top and you'll be warm. In most cases a vapor barrier will do very little. But FWIW paper or foil should go to the "warm" side. Also, HD has two different machines. The cheaper one used to blow cellulose (ground up newspaper) was free if you purchased 10 bags of insulation. Its literally was shredded news paper so there was no need for any special precautions. The other one (had a picture of Pink Panther) was for blowing fiber glass insulation into attics. I believe it puffed the insulation up more and since it uses fiber glass insulation, tyvex, goggles and a respiratory would be my recommendations. |