How to Insulate a Plywood Ceiling

An air duct running along an unfinished, plywood ceiling.
  • 4-10 hours
  • Beginner
  • 200-500
What You'll Need
Rolls of insulation
Staple gun
Finishing nails
Flat bar or pry bar
Face mask
Utility knife
Eye protection
Step ladder

Many may be surprised to learn that most plywood ceiling structures do not have a base level of insulation that was installed when the room was built. Instead, they may have light layers of foam sealant. There are generally no sheets of insulation installed into the cavity between the ceiling and support beams. This DIY guide will show you how to install this missing insulation with step-by-step instructions.

Step 1 - Remove the Old Sheeting

First, remove the old plywood ceiling panels carefully and set them to the side. Generally, a flat bar works best for this, and sometimes you can counter pull the old nails, saving the old panels for re-installation. Be sure to wear eye and face protection to keep flack and dust out of your eyes and lungs during removal and installation.

Step 2 - Installing Insulation

Where the plywood ceiling has been removed, you should see the cavity between the support beams in the ceiling. Take your batts of insulation and start to mount them into the ceiling starting at one end and working to the other, stapling them every four to six inches on both sides. Use the utility knife to cut them at the ends and staple the ends up into position.

Plywood ceilings are usually found in mobile homes or trailers, which have quite a different structure from a regular home. Most of the stud walls are only two to four inches deep, as opposed to the six-inch depths in a regular home. Be sure that when you buy your insulation you get the correct thickness to prevent bulging. Once installed, the insulation should be flush with the beams of the ceiling.

Step 3 - Reinstalling the Panels

Simply take the sheets from your plywood ceiling and reinstall them using your hammer and finishing nails. You can countersink them to obscure them from view. Your sheets should fit right over the top of the newly-installed insulation.

Use your utility knife to clean up any edges or corners that interfere with the placement of your panels. Placing the nails in different spots than the ones in which they were originally creates a stronger hold. You can do this by making sure all the old nails have been removed from the panels before installing them and avoiding the old holes to get a nice solid bite into the support beams.

Step 4 - Cleanup

To clean up after insulating your plywood ceiling, simply vacuum or sweep up any flakes from the floor. On some ceilings, you may get this strange-looking foam that falls down. This is not important and is only the remnants of a very poor attempt at insulating the cavity in the past.