A - The maximum performance of foam board insulation depends heavily on proper installation. Therefore, it's best to have a certified insulation installer do it. If you'd like to have it installed professionally, you should do the following:

• Obtain written cost estimates from several contractors for the R-value you need. Don't be surprised to find quoted prices for a given R-value installation to vary by more than a factor of two.
• Ask contractors about their air-sealing services and costs as well, if needed.

To evaluate batt installation, you can measure batt thickness and check for gaps between batts.

If you want to install it yourself, you should try to obtain instructions and safety precautions from the manufacturer. Carefully follow these instructions. You should also check your local building and fire codes.

Radiant Barrier is unlike mass insulation which only slows down or resists heat transfer. RB reflects heat. Heat always goes cold by natural law, the problem is how to keep the heat in in the winter and how to keep it out in the summer. There are three ways in which heat goes from warm spaces to cold spaces: CONDUCTION is direct heat flow through a solid object such as a wall or a ceiling. CONVECTION is heat movement through air, occurring when air is warmed. The warm expands, becoming less dense and rising. RADIATION is the movement of heat rays across air spaces from one warm object to a cooler object. The heat we feel from a wood stove or a quartz space heater is radiant heat. All objects and bodies give off radiant heat. Even the insulation in your attic gives off radiant heat to the cold attic space in the winter, and to the living space in the summer. Regular insulation won’t stop radiant heat loss. Radiant heat must be reflected with a radiant barrier. 

A new closed-cell polyurethane foam insulation uses HFC-134a, a nonchlorine blowing agent, which is not athmospheric ozone-depleting. The new product offers a reported aged R-value of R-6.5 per inch thickness. Because of the new blowing agent, it is roughly three times as expensive as traditional polyurethane insulations. Although it does not affect the ozone layer, a recent study showed that high concentrations of HFC-134a in the environment may damage wetlands and plant growth.