Many people have spent a great deal of money on insulating their homes, only to find that it does not have the desired effect. They still get draughts and hot-spots in their home despite installing their insulation to the recommendations of the insulation manufacturer. The main reason that people get disappointed with their insulation job is that they did not do enough research over the R-value of the insulation required. It is the R-value of the insulation that is the measure of it's insulation properties. Energy agencies like the DOE (U.S. Department of Energy) and the IECC (International Energy Conservation Code) publish leaflets that give recommended R-value of insulation levels that should be used depending on the environmental conditions in your area.
The R-value of insulation is obviously an important measure so it is important to understand exactly what it is. It is a measure of the amount of heat flow that an insulating material can resist. The lower the R-value of an insulating material the less effective it is so always go for the insulation with the highest R-value.
When assessing the R-value of insulation you may be concerned to see that two different form of insulation have the same R-value but are different thicknesses. Do not be alarmed. All forms of insulation will have different R-values dependent on the material that was used to construct them. They will have gone through an independent test procedure to receive their R-value rating so you can be sure that you are comparing on a like for like basis. This R-value of insulation testing is performed in controlled conditions so the R-value that you achieve in your insulation installation may not bear much resemblance to the R-value quoted on the insulation that you buy.
The R-value of insulation when installed can be reduced by air leaks and water ingress. Because of this it is extremely important to ensure that the area you are insulating is sound from a construction point of view before you install you insulation. If water is allowed to combine with the insulation it will reduce the R-value of the insulation and negate the extra money spent on getting the best R-value of insulation that you could afford. Water ingress can be prevented in most places by adding a waterproof membrane to the surface that you are going to insulate before you install the insulation. This will help keep out draughts as well, ensuring that you get the full benefit of the R-value of the insulation you have installed.
The R-value of insulation materials varies from substance to substance. Blown in cellulose insulation has a higher R-value than fiberglass insulation (3.6 per inch compared with 3.23 per inch) and polystyrene weighs in with an even higher value still (4.10 per inch)
The R-value of insulation that you choose depends on the area to be insulated and the climate that you are insulating in. Ensure that you fully research your subject and you should not be disappointed.
The lower the R-value of an insulating material the less effective it is so always go for the insulation with the highest R-value