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Radiant Barrier Millbrae

Radiant Barrier Millbrae

One of the reasons our radiant barrier products are so popular with DIY homeowners and professional radiant barrier installers is that they are inexpensive and easy to install. Installation methods include radiant barrier draped over the rafters, applied directly to the roof sheathing, stapling to the bottom of the rafters, and even laying radiant barrier on top of the attic floor insulation. Some of these installation methods are preferred over others, but all have sufficient research and testing to demonstrate their performance. The installation method that is right for you may depend on many factors like climate, roof pitch, attic height, construction stage, and even the location of your ducts and HVAC equipment. There are certain pros and cons for radiant barrier applied in each of these methods, which we have addressed below.

Top Side of Truss Under Sheathing:

In new construction, the most popular application for radiant barrier in warm climates is to have it draped across the roof rafters, under the decking. This is makes it easy for the roofers to install in a short period of time, assuming the weather is accommodating. Many builders have radiant barrier applied to the roof sheathing directly to cut back on time spent up on the rafters.


  • It is inexpensive and easy to install as a roof is being repaired or replaced
  • It decreases the temperature of the A/C equipment and ductwork in the attic
  • The reflective side is facing down, where dust, dirt and debris cannot settle


  • Slightly less efficient by allowing heat to emit through the uncovered rafters
  • It is only viable if the roof is being replaced, and is not feasible in existing homes
  • Misconceptions about radiant barrier damaging shingles

Below Bottom Chord of Rafters:

In an existing home, especially in warm climates, the preferred method for installing a radiant barrier is stapled to under the roof rafters. A heavy duty radiant barrier should be used for this application, so that it can hold staples and not come down over time. This method has many of the same advantages of installing radiant barrier under the decking, while minimizing many of the concerns.


  • It decreases the temperature of the A/C equipment and ductwork in the attic
  • Can be applied in an existing residence without the need for replacing the roof
  • The reflective side is facing down, where dust, dirt and debris cannot settle
  • Covering both the roof rafters and attic walls improves the efficiency


  • Low soffit areas may be difficult to reach, depending on the pitch and height
  • Care must be taken when working around obstacles like ducts and trusses
  • Certain areas like vaulted and cathedral ceilings may be completely inaccessible
  • Misconceptions about radiant barrier damaging shingles

Over Ceiling Insulation:

A radiant barrier applied horizontally over the attic floor insulation is the more popular application for existing homes in cool climates. The heat escaping in the winter will be blocked at the insulation level, while heat radiating down in the summer will still be blocked from reaching the living space. For this installation method, a lightweight and perforated radiant barrier may be best. The light weight prevents the radiant barrier from weighing down the insulation, and the frequent perforations allow moisture in the insulation to escape.


  • Performs in both cold and warm climates with little or no attic ducts
  • Easier to reach places like low pitched attics and vaulted ceilings
  • Attic walls can also be covered to maximize the efficiency of the radiant barrier
  • This method is easy to install and no special tools are required


  • Once covered, the ceiling joists may be difficult to see
  • Storage cannot be placed on top of the radiant barrier
  • Dust settling on radiant barrier may negatively affect the performance
  • Non-perforated or poorly perforated radiant barrier may trap moisture

The advantages and concerns listed above are intended to help you decide the best installation method for your particular situation. Before you begin any new construction or retrofit radiant barrier project, carefully read the manufacturer’s installation instructions and safety tips. It is the position of Innovative Insulation Inc that safety should always be a top priority, even when radiant barrier is not being used. When working with or around other insulation products, like fiberglass, rock wool, asbestos, foam or cellulose, please consult the installation and safety requirements specific to those products. When installed in the method right for you, radiant barrier works wonderfully at reducing the heat transfer into and out of the home. Please feel free to contact us if you have any further questions regarding these or any other installation methods.


Air ducts get damaged from a number of factors such as age, poor design, and rodent damage.

Damaged duct work or air duct leaks affect the indoor environment in two main ways:

Cold air is lost before it effectively cools the indoor space. This makes your HVAC system work harder, using more energy and driving your utility bills up.

Leaks in the duct work introduce contaminants to the circulating air. This includes mold, dust, mites, pollen, bacteria, asbestos and other allergens.