Polyurethane foam insulation is one of the most common DIY projects for the homeowner today. As more people work to make their homes more energy efficient, more types of insulation have become available. Let's take a closer look at polyurethane foam insulation, and see what it has to offer.

Polyurethane foam insulation is a closed-cell insulation material that contains a low-conductivity gas within its cells. This gas, usually hydrochlorofluorocarbons, gives this foam an R value of about R-7 to R-8 per inch; that's pretty impressive.

Over time, however, this R value can drop due to a phenomenon known as thermal drift. As the foam ages, the low-conductivity gas can end up replaced by air.

Thankfully, this normally occurs over the first two years or so after the insulation is installed, and then things settle down.

If you started with an R value of R-9, for example, you will probably end up with something closer to R-7. That's where it will stay, unless the foam is damaged in some way.

There are three basic installation procedures for polyurethane foam insulation. The product can be sprayed on as a liquid, which then hardens, or can be installed as rigid foam board.

It can also be laminated into panels with different types of facings. Of these, the liquid application is the most effective, and the least expensive.

The liquid molds itself to the surfaces and cavities where it's applied, which means less chance of air leakage. However, when it's applied to existing homes (not installed during construction), there's always the chance of wall damage due to the foam expanding too much.

There are special slow-expanding foams produced now to help alleviate that problem. If you're looking at installing polyurethane foam insulation in the form of rigid boards or panels, you're probably going to want to look for one with a foil facing.

These panels have much less thermal drift, if any, and the reflective foil can act as a radiant barrier. That will add another R-2 to the rating; that's nothing to sneeze at.

Whatever form of polyurethane foam insulation you choose, be sure to do your research thoroughly before proceeding. This is also a situation where, unless you're an experienced do-it-yourselfer, you might consider hiring a licensed contractor to do the job.

Between tax credits for energy improvements made to your home, savings on your energy bill, and increased resale value for your home, you'll still most likely come out ahead on the project.