Does plywood flooring have to be removed before adding insulation?
dagored53
| Posted in General Questions on
My attic currently has a settled 8″ of blow in insulation. I am adding more batts at an R-30 value. Previous owners installed plywood on joists for storage and nailed it every 6″. Can the batts I’m addind be placed over plywood or must it be removed?
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Replies
Dan,
First of all, I hope that air sealing work was performed before the insulation improvements were made. (Here is a link to an article with more information on the topic: Air Sealing an Attic.)
You haven't really explained whether there is an air space between the top of the blown-in insulation and the plywood subfloor. If there is an air space there, the plywood should be removed so that the new batts are in contact with the existing insulation. You don't want an air channel between the two layers of insulation.
There are several other issues worth discussing, however.
1. If you want to make the insulation deeper, adding more blown-in insulation (blown-in fiberglass or cellulose) would be better than adding batts.
2. If you want to keep a useful walkway in your attic, you probably want to:
(a) temporarily remove the plywood subfloor;
(b) add new framing to support the plywood at a higher level (above the new insulation);
(c) install deeper insulation;
(d) re-install the plywood above the top of the new insulation.