question about attic insulation
barntimber
| Posted in Energy, Heating & Insulation on
Hey all! I’ve got a client who needs his attic insulated. He had an energy audit and was told that he should insulate to R60. I’ve got everything figured out concerning square footage and depth and all that jazz but I have a question. Here it is. Would it make sense to pull the floor boards in the attic so the insulation is actually sitting on the sheetrock, rather than blowing it in on top of the floor boards, thus leaving an uninsulated joist cavity between the ceiling and the insulation above? Would this make much difference or not worth the trouble? Any comments or experience appreciated. Thanks!
Replies
Dunno the answer, but you don't have to pull the floorboards to blow in under them -- some drilled holes would do it. I do think that blowing under 'em would give you a better air seal, but you won't get R-60 unless you add more on top as well.
Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.
Thanks for your guidance. Appreciate the time.
Is the attic completely floored, or do the floorboards just provide pathways to walk around?
If it's just pathways, I would pull them 'cause they're gonna be useless buried under the new insulation. Sooner or later, somebody is gonna miss one and ..........! - lol
I disagree ... knowing there is solid footing under the insulation gives one more confidence to navigate the attic to take care of 'issues'.
That's true if you know that the flooring is everywhere you might try to walk. I've been a few attics, however, where the "flooring" just provides pathways and the rest of the attic is "open". If I were insulating one of those, I would definitely remove the floor boards.
Good point ... then add catwalk indicators at the roof joists ... or something like that.
The entire floor is covered, save a small section in the corner for some reason. Someone suggested just drilling some large holes and blowing-in that way. Makes sense. Now I'm thinking about sheeting the rafters as well. With 2'' polystyrene sheets?. I've found some information that claims this will help the ac unit keep up because the attic will stay cooler? What do you think about that all?
I think that I would talk to that auditor and get his/her take on the necessity of blowing it under the flooring. Off the top of my head, I think that blowing new loose fill on top of the flooring should do the trick. As long as the joist bays are reasonably air tight, the dead air cavity (5.5"?) is a pretty effective insulator. The time needed to drill holes and blow it under the flooring will probably double (or more) the time needed to do the job.You might find it more effective to put in a thermostatic controlled fan or two to pull the hot air out of the attic.
I guess I wouldn't putt the flooring up. The air cavity does give you more insulation value (i.e. dead air space). As the one poster suggested, you can drill holes and blow if for some reason you felt compelled to insulate that joist space. Is the attic well vented? Are you putting in a vapor retarder first? (Just asking, not necessarily suggesting). Don't forget to protect and retain all attic venting including (especially) the eave venting.
th wood can hold more weight than drywall. with the insulation on top of the boards the air cavity is not an issue. the issue is, do they want to store items in the attic
No it isn't ... since adding R-60 will likely be far more thant the depth of the joists ... not much storage in this case.