Walls Insulation

You really can’t put batts in old walls without tearing apart the drywall and completely redoing it. So, if it’s a home renovation project where the walls are already opened up, an addition, or new construction, batts is a viable option. Otherwise, blown in insulation is the way to go (and you can, of course, blow insulation into new construction as well.)

Batts are sized by manufacturers to fit snugly between standard sized wall cavities (between studs). Thus, each batt need only be cut to length and pressed gently into position.

The paper backing of batts extends beyond the insulation around an inch, so that the pieces can be stapled to the studs and overlap with each other there, thus forming a complete wall envelope.

One should never compress batts insulation when installing it since that can make it lose much of its R-value. And also realize there are fiberglass batts with different R-values that are recommended for exterior walls, interior walls, attics, and basements.

Fiberglass is the most common form of batts installed in walls (and the least expensive type), but there are other alternatives like cellulose, cotton (recycled denim), mineral wool, and more, that may offer a higher R-value and have a greater percentage of recycled material in them.

When installing batts in walls, you must notch around electrical boxes and cut around pipes and cables. But you never press batts behind pipes since that would compress it.

Sometimes, it’s best to also use spray foam to fill in small gaps inside the wall that might allow for air to pass through or for condensation to build up. Many batts have a paper backing that acts as a vapor barrier, but open faced batts are also sometimes used.

And for exterior facing walls, a vapor retardant poly film may be installed over the batts and stapled to the studs to keep it in place – this will help maximize energy efficiency with the walls that could potentially be the coldest otherwise.