Adding Attic Insulation and Keeping Storage

Old 05-08-08, 01:27 PM
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Adding Attic Insulation and Keeping Storage

Okay, this is my first post here, though it certainly isn't going to be my last since I have a LOT of questions.

But for starters, I'm looking for advice on adding insulation to my attic. I've searched the forums and found quite a few similar questions and answers, but I ant to make sure I'm on the right track and see if anyone has some advice on my specific situation.

My house is a slit ranch on Long Island, NY. The recommended insulation for my attic seems to be R-49. My current insulation is... god only knows. The joists in the attic are 2x6s and seem to be 24" on center. The spaces I can see all appear to be filled in with some sort of yellowish blown in fiberglass. There are no batts to pull up and read an R value off of. The insulation does seem to fill the entire cavity. It's hard to tell though because most of the attic has been covered with plywood for storage.

At the moment I am adding a few inches of blown cellulose insulation, since it seems fairly cheap, fair effective, and not too difficult for me to do it myself. I'm still going to need the attic for storage though. Which means my best bet is to lay down some 2x8s perpendicular across the joists to crease a space to fill with insulation, then but plywood on top, right? I just have two major concerns...

1) I have a large house fan mounted in my ceiling. When I turn it on, I pull air throughout the house and up into the attic. Is this going to end up blowing insulation all over my attic? I suppose the fact that I plan to cover the insulation with plywood would help avoid that, but the edges of the attic would be uncovered for ventilation from the soffits. I also get pretty good cross ventilation through the gables at either end of attic. Am I going to end up blowing cellulose out of my attic and across the neighborhood the next time I turn on the fan?

2) Should I be worried about the extra weight running 2x8s across my joists will add? I've lived in this house for over 25 years, since I was a kid, and we've never had any ceiling problems from storing stuff in the attic. Of course, we don't put anything too heavy up there. Mostly Christmas decorations, luggage, out of season clothing, perhaps some magazines. Things like engine blocks and my "Lead Weight of the Month" collection stay in the garage. A little extra lumber isn't likely to start causing me trouble, is it?

And a few other minor questions: If I add 2x8s or the like to leave insulation space, how far apart should I place them? If 24" as far out as I should go? Is 1/2" plywood sufficient, or should I use 3/8"? Is it okay to leave the old plywood flooring there, or am I best off pulling it up (perhaps even reusing it?) Leaving it there WOULD make it a lot easier to work up there while I blow in the cellulose.

And, of course, is blown in cellulose the best material to use for this, or is there some alternative I should be considering?

Thanks in advance for any advice!
Old 05-20-08, 03:40 AM
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Kinda confused w/ the 2x8's but this is what I was told and have done. I have a 1940s house that had no insulation anywhere. I have a floor in the attic and I tore up a 12" strip down the center of the floor, shoved the hose from the cellulose blower to the end of each side of the house and filled in the joist spaces. I have gable vents and a ridge vent and no soffit vents so I was ok to do this. I got a quote from a contractor to do my walls, and I took him to the attic to show him what I did. He said that the 8" I blew in between my joists was not enough. I need another foot of cellulose on top of my floor. He said I could blow in the cellulose and then where I wanted my storage was to go buy 3" blue foam board insulation and put that down and use 1/4" or 3/8" plywood to put that on top of the foamboard and that would be sufficient for putting boxes or what not on.
The weight of 2x8's, I am not sure on. I hope someone else can help you w/ that. I hope I helped answer some ?'s. Good Luck

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