The material was first invented by Dow Chemical. It is made from a compact polymer that water can not pass through. This makes it ideal for dealing with the moisture that commonly accumulates in the basement of residential homes. It works well in concrete flooring, which also makes it beneficial for use in the garage. The material is so resistant to water that it is also used in the construction of docks.

Despite its usefulness, there have been significant changes in the way that it is used as an insulator. In the past, it was sandwiched between two pieces of plywood, and either screwed or nailed to the boards. This method was effective, but not ideal, considering the fact that the nails put holes directly through the insulation. It also took up quite a bit of space, reducing headroom in the basement. There are some contractors who still use this method today, unfortunately.

One of the first changes that was made was to start adhering the polystyrene sheets directly to the concrete floor. The plywood was then installed on top using adhesives, rather than nails. While this system was an improvement, it required concrete screws to prevent the plywood from warping out of shape.

Today, subfloors have been improved upon to include air gap insulation. This system makes it possible to install the insulation without needing to secure it to the concrete. This offers several advantages because there are fewer materials, installation is easier, and there is no wood to break down.

These new panels are held in place using airtight gaskets, so that the insulation is literally floating on air. A secondary advantage of this is the fact that it protects families from radon gas.

XPS is also highly effective as a wall insulator. Fiberglass insulation is not as effective at preventing moisture from creeping into the basement, and it can only be installed between the wall studs. XPS can cover the entire wall, and is much better at resisting moisture.

Originally, the insulation was installed on the inside of the basement. Newer homes install it either on the outside, or even directly inside of the concrete. There are, of course, practical concerns that make it difficult to install the insulation on the exterior of older homes. It is still considered to be more effective to install it in the interior than not at all.

While the methods have changed over time, the effectiveness of the material has only improved. While it is not the only insulator available, polystyrene is one of the best.

Regardless to whether you have batt or blown insulation, you can put batt insulation on top. Rolls of this type of insulation usually measure 16 inches wide. To determine the amount of insulation that you need to buy, measure the length and width of your attic. Divide the width by 16 and multiply the result by the length to determine linear feet required. If there is insulation, measure how deep it is and then add enough extra to bring it up to the 18 inch depth.

If there is already insulation present, you should buy unfaced rolls of batt because you do not want to create a second vapor barrier. If there is not insulation, then the rolls with paper backing are okay to use. Unroll the insulation and lay it in the attic, paper side against the attic floor. If you are placing the batt over existing batt, roll it out and lay it in the opposite direction to eliminate any seams to prevent energy loss in between the rolls.

Adding this additional insulation to your attic can add a substantial savings to your wallet each year. Estimates are around $145 saved for 1,200 square feet of ceiling area. When you are installing it, make sure that you do not block any vents, or air openings, and do not cover any of the recessed light fixtures. Once you have installed your insulation and start seeing the savings on your energy costs, you will be astonished and wonder why you did not make these changes sooner.

Making sure all the ductwork is properly insulated makes good money sense. When buying a new system make sure it is already insulated. If it is an older system, have a professional come in to perform a maintenance check, especially at the beginning of the winter and summer months. Always change out filters in the fall and spring. If there is air escaping, the system will have to work harder to heat or cool the home, wasting hundreds of dollars. Unless you are a professional, attempting to do the job yourself is probably not a wise decision. However, here are some simple things you can do yourself.

A thorough check includes examining the complete system for air leaks and holes. Look for joints that have become separated. If any are found, use high quality duct tape to seal them; you do not want the tape disintegrating or cracking from age. Make sure to have a barrier on the outer insulation so as not to have moisture vapor accumulate.

Upgrading to a newer system or maintaining your existing system, is vital in keeping the heating and cooling costs down, ultimately preventing pollution and giving you a quieter system. For more great tips on heating and cooling in your home, check out the Heating and Air Guide.