Plywood over attic insulation?
Question:I need to replace my current attic insulation (it has compacted over many years) with something that works better. From my research, a loose fill 12" or so should do the trick. I also am considering putting up a radiant barrier along the inside of the roof. Is there any danger of putting plywood boards over the new insulation or could it actually help with heating/cooling costs?
I understand that the electrical wiring ceiling wiring will be covered so if there is ever a problem the boards would have to come up.
Any other pros and cons?
Thanks.
Answers:
Loose fill insulation may not be your choice if you plan on putting down plywood. Since the plywood would require you to compact the air space out of the loose fill, eliminating it's effectiveness. You might look at alternate insulating products, including foam board.
Installing a radiant barrier is a good idea. But this would need to be placed on the roof deck, not the top of the joist framing where the insulation is usually placed. It's usually difficult to impossible to place this from the attic side. The only other practical method to do it would be to wait until you need to replace the shingles, and add radiant barrier roof deck to that job.
In most houses, getting a 4' by 8' sheet of plywood into the attic is nearly impossible without cutting a bigger hole in the ceiling. If you can do it, there really are no down sides (except the cost) and the up side is you are a whole lot less likely to put your foot through the ceiling!
I'm considering the radiant barrier too - I haven't decided which setup I'm going to use though.
Good Luck!
From what you've said, that is the normal process. It will also provide for extra storage once the solid "flooring" from the plywood is in place. Just curious though about the 12" insulation. usually 2 X 6 or 2 X 8 boards are used as rafters. The 12" insulation would have to be compressed, which actually defeats the purpose of the loose insulation. Wouldn't you use something not quite so thick?
good luck
You normally don't remove the old insulation but put more over it. I don't know if you should use thick bat insulation or just pay somebody to put in blow in insulation.
PLYWOOD HAS ALMOST NO R-VALUE it won't do a thing to help with the insulation.
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