Insulating a Mansard Roof

Lead Image
  • 2-30 hours
  • Intermediate
  • 50-1,000
What You'll Need
Foam insulation
Vapor barrier

If you own an older house, you may have to figure out how to insulate a mansard roof. These types of roofs are not very easy to insulate, as they have very little attic space, and also need to be quite well ventilated to prevent the wood from rotting. To insulate the roof, you will need to use a combination of insulation to fully protect the roof.

Step 1 - Add a Vapor Barrier

One of the best ways to protect your mansard roof from the problems of ventilation is to use a vapor barrier on the inside. This barrier may not be fitted to an older home, and you should consider getting a contractor to install one below your floor. If you are not keen on this, apply the plastic barrier to the attic floor.

Step 2 - Add Caulking

Home with Mansard roof

Once you have added the barrier, caulk around the edges of the floor. Don't block all of the holes in the roof, as these are essential for ventilation.

Step 3 - Add Foam Insulation

The best sort of insulation in this type of roof is the foam insulation. Spray this into each of the crevices in the roof with the foam, eventually building up to a complete layer.