Can You Use Spray Foam Insulation on a Cellar Ceiling?

Spray Foam

• Spray foam is a type of insulation that is sprayed onto surfaces and sticks there. After it is sprayed it expands, filling up gaps and drafts and sealing off walls, floors and ceilings from cold drafts. You can buy spray foam in cans for small applications, but larger applications are usually done by professionals with serious equipment. Before hiring someone to apply spray foam to your cellar ceiling, consult with a professional about the best solutions for your insulating needs. If you have a dry cellar, other forms of insulation may be more effective and less expensive.

Insulating a Cellar

• The best way to insulate your cellar depends on a number of factors. If you live in a very old house with a drafty, dirt-floored, damp cellar, it's probably best to insulate the ceiling and isolate the rest of the house from the cellar. If your cellar is newer, has no problems with moisture, and has enough headroom to be used as living space, it might make more sense to insulate the outside walls of the cellar and incorporate it into the finished part of your home.

Drafts

• Spray foam insulation on a cellar ceiling is one of the most effective ways to cut out drafts and cold floors, especially if your house is built on an old stone foundation. The foam should be sprayed into the cavities between the joists, directly onto the underside of the flooring, leaving the bottom surfaces of the floor joists clean. The most important areas are the outside walls of the cellar in between the floor joists. Because these parts of the wall are above ground level, these are the areas where most of the cold drafts come from.

Alternatives

• Spray foam is a more expensive form of insulation than many others, so it should only be used in situations where other forms of insulation are not appropriate. An advantage of spray foam is that it's impervious to damp and moisture, so it can be used in places where fiberglass wouldn't work. Rigid foam panels are also waterproof and can be used with less expense and hassle in the same places as spray foam. However, spray foam is much better at getting into irregular spaces and cracks. One way to reduce the expense of spray foam is to insulate the cellar ceiling with rigid panels, then fill in around their edges using a can of spray foam.