Spray Insulation is worth looking into for many reasons, even if it’s not always the ideal solution. Although it is more likely to be the best option for new construction, its features also serve the needs of many existing homeowners who are adding to or trying to improve their homes.
For example, even if the spraying must be done by professionals, and therefore is more costly than other options, the high R-value of spray insulation can make it cost- effective over time, through lower heating bills. In very cold or hot climates this advantage may be well worth the cost.
Spray insulation also carries the advantage of filling uneven areas well. The sprayed foam expands to fill cracks and fit into irregular spaces that would be difficult to work around with other kinds of insulation. The do-it-yourself handyman might be very relieved not to have to work in difficult nooks and crannies, and to just let expansion of the foam do the work.
Another advantage is that spray insulation adheres well to the surface onto which it is sprayed. If a house is being expanded upward, to a second story, then spray insulation under the new floor will be securely in place and offer good insulation for years. It might be a better solution than trying to attach other forms of insulation in such a space.
There has been some debate about the moisture barrier qualities of closed-cell foam spray insulation. Such foams, e.g., polyisocyanurate or polyurethane, offer higher R-value than open-celled foam, e.g., polyicynene. The latter allows for some passage of water vapor after the insulation is installed. The advantages and disadvantages in relation to moisture barrier issues are important to discuss with an insulation expert on a case by case basis.
When a wall is already closed in, the most practical and economical way to insulate it is with spray foam insulation.
Foam is not the only product that can be sprayed for insulation. Cellulose and fiberglass fibers also can be sprayed, if they are mixed with some sort of adhesive or foam to keep them in place.
Because various forms of insulation can be used together and because every situation has its own considerations, the homeowner considering spray insulation would be well advised to consult several insulation contractors to weigh all the options before deciding how to proceed. Ask each of them to make a bid in writing for insulating a defined area to a certain R-value. It might also be useful to have a home energy audit if your purpose is to increase the energy efficiency of your house. Contact your local utility company for information on this.