Radiant barrier insulation

What is in store with radiant barrier insulation?

Radiant barriers are also known as radiant insulation that reflects the transfer of heat by the way of thermal radiation. Radiant barriers do not perform in the same way in which standard glass wool or mineral wool batt insulation would work. Instead, the radiant barrier will use its reflective surface to reflect radiant heat, this works when you have a cold surface on one side and a warm surface on the other side. A radiant barrier generally does not carry an R-value as its resisting heat or restricting heat flow it reflects radiant heat. Radiant barriers will perform equally well in hot and cold climates.

As radiant barriers reflect radiant heat and do not carry an r-value they can also be called up as thermal/heat insulation.

Radiant barrier in your roof

So what happens when you put a radiant barrier into your roof. Well first of all if you do not use one in your roof space what will happen is your shingles will get very hot on the outside from the beating sun which will, in turn, warm up the underside of the shingles. This will, in turn, heat up the OSB underneath which will also in turn heat up the under-roof side of the OSB thus heating up the attic space. By installing the reflective radiant barrier it will reflect this heat outwards thus keeping the inside room temperature at a comfortable level.

It is also possible to use a white shingle tile or a reflective tile on your roof which will perform quite well to reflect the heat outwards but will not perform as well as a radiant barrier will and also a white shingle or reflective roof is not always aesthetically pleasing to the eye.

Radiant barrier can also be applied to insulation during the manufacturing process you will notice some companies such as Owens Corning / CertainTeed / Johns Manville etc all fabricate a foil-faced glass wool insulation. Other insulation types like Polyisocyanurate insulation (Polyiso / PIR) also have a foil face and again this is purely as a reflective barrier and will act similarly to radiant barriers.

Radiant barrier in your attic

The most common application here is laying the insulation radiant barrier over the glass wool or mineral wool insulation. However, there are some precautions to take as per the Reflective Insulation Manufacturers Association International whereby they advise that perforations be installed into the reflective insulation to allow for the movement of air and vapors that may get trapped between the reflective insulation and the ceiling. This could over time cause mold build upon the underside of the reflective insulation or the glass wool / mineral wool insulation. Perforations the size of at least 5 perms are recommended here. Another downside to this application is the buildup of dust over the reflective foil on the upside. This will over time decrease the performance of the radiant barrier, so maybe best to set your alarm for once every 6 months to go up and wipe off all that dust.

Another application for the radiant barrier in your attic could be to the underside of your rafters. A simple staple gun and some elbow grease will get the job done in no time by stapling the radiant barrier to the rafters. This is a quick and easy fix for your attic and will be very effective at reducing your heat loss and reflecting your heat back into your home.

Radiant barrier in your Walls

Again much like with your attic it is recommended that your radiant barrier can breathe here to avoid any buildup of high moisture content air within the cavity space behind the radiant barrier. Again the radiant barrier can be stapled to the stud framing at whatever centers the stud framing is at. Again just make sure there is plenty of space for the movement of air and nothing will get trapped in behind that wall.

If you wish to use a radiant barrier on your external wall then again you can vent the cavity with a breeze block or wall vents can be used to allow for the circulation of air from bottom to top. This is vital to get right so make sure when the job is finished that nothing has fallen in behind the vents or anything is blocking the airflow through them.

Radiant barrier in floor, crawlspace, and basement

Radiant barriers work very well for floors and crawlspaces especially when underfloor heating systems are deployed. The radiant barrier will prevent the warmth from passing through to the crawlspace or basement. Just like the walls and roof applications the radiant barrier can be stapled to the underside of the floor joists again at whatever centers the floor is already at. In this situation, however, where a crawlspace is under the floor it is not a good idea to perforate the radiant barrier as the moisture from underneath will pass through the barrier into the underfloor void and into the living space of the home. So the radiant barrier will act as a vapor barrier also.

Benefits of radiant barriers and reflective insulation

Radiant barriers are most effective in hot climate like Texas and Florida. In hot climatic conditions, radiant barriers reflect up to 97 percent of the solar radiation. Other benefits are mentioned below 

Radiant barriers are not affected by humidity

Radiant barriers with perforations helps prevent moisture build-up and allow airflow

Radiant barriers adds R-value to boost thermal efficiency

Radiant barriers don't emit harmful particles

The quality of R-value never degrades in radiant barriers

Radiant barrier insulation can be installed over existing insulation in your home

Radiant barriers are made of inorganic material 

radiant barriers are great insulators for water pipes, hot water tanks, and wrapping ducts

radiant barriers prolongs the life of heating and cooling system

Helps lower energy bills all year round

Radiant also increases the efficiency of ductwork