When your house is not properly insulated, the walls and floors will be extremely cold in the winters and the air inside the house becomes too hot in the summer days. This will promote mold growth all over the walls and basement. For all these reasons, we want a well-insulated house for ourselves.
Insulation uses air to create a barrier so that its heat conductivity decreases and the loss of heat through convection is prevented. Thus, the high heating cost of your house during the winter and cooling cost in the summers can be saved. Rigid foam insulation is considered as one of the most effective insulators as it can entrap large volumes of air inside it. It not only slows down heat flow through the house, it also prevents moisture penetration through the structural elements of the house like wood and steel.
Types of Rigid Foam Insulation
There are different types of panels that are being used for insulation. The resistance of the foam towards heat flow is measured by its R-value. It is rated as per inch of thickness and it may vary from R-4 to R-6.5. The most popularly used insulation boards are discussed below along with their properties.
Expanded Polystyrene (EPS)
This is a closed-cell rigid foam board insulation material and is often referred to as beadboard. A mixture of loose and contracted polystyrene beads and blowing agent is heated in a container so that the beads get expanded. Then they are injected into a mold and are subjected to a higher temperature and pressure. Thus they expand further to form EPS blocks which is then given the required shape. Its R-value range lies in between 3.8 and 4.4 per inch. The density of EPS depends on the kind of bead used to prepare it.
EPS, when used as roofing material, should be dense enough so that it does not get damaged if someone walks on it. When it is used on walls you can select the one which has a lesser density. You can use small beaded foams to insulate concrete blocks or hollow wall cavities. The spaces between the beads of EPS tends to absorb water. Hence, vapor diffusion retarder should be attached to the panels before installing the insulation.
Extruded Expanded Polystyrene (XPS)
This is another closed-cell insulating material and its R-value is about 5 per inch. For manufacturing XPS, polystyrene pellets are liquefied by mixing various chemicals with them. A blowing agent is injected into the thick liquid so that gas bubbles are formed. Then it is passed through a shaping die and is allowed to cool down. Thus the panels are ready and can be cut as per requirement. The qualities of XPS are far more superior than EPS. Its density has higher consistency and possess greater compression strength. But XPS has good resistance towards moisture absorption and is ideal for insulating basements.
Polyurethane and Polyisocyanurate
These type of insulation materials are found both in the form of liquid spray as well as rigid boards. They consist of gases with high thermal resistance in between the cells. The R-value of these foams can vary in between 8 and 9 per inch. However, it tends to drop to 7 within two years as the low conductivity gas escapes and is being replaced by air. After that the R-value remains steady unless the foam get damaged. Often foil or plastic facings are used in these foam panels to minimize the escape of gas.
The insulation can be installed very easily with the help of nails or glues. Still, it is advisable to take the help of professionals for this home improvement project. The cost is much higher as compared to other insulating material like fiber. The cost varies according to the thickness and type of rigid foam used.