Bubble wrap insulation started as bubble wrap for packaging and shipping. Manufacturers added reflective foil to the ⅜” thick material to turn it into insulation. The polyethylene-wrapped air bubbles provide an R-value of R-1.0 – R-1.1.
The correct technical term for bubble wrap insulation is radiant barrier. It’s as valuable as reflective insulation, keeping the heat out of a home. Contractors often tape bubble wrap reflective insulation to south-facing or west-facing windows to prevent some of the solar gain from heating the rooms.
Bubble Wrap Insulation Effectiveness
Bubble wrap is effective in warm or hot climates, where it can reflect heat from the sun. The need in these conditions is to prevent outside heat from entering a building. To work well, it has to face an open-air space.
Radiation is the direct transmission of heat from a warm surface to a cooler surface. Bubble wrap works in two ways:
- Reflection. Heat bounces off reflective surfaces.
- Emissivity. Highly emissive surfaces will throw off the heat that they absorb. Bubble wrap requires at least a one-inch air space on its face to get rid of the heat.
Bubble wrap adds an R-value of R-1.0, which is an insignificant increase that should be considered secondary to the radiant barrier properties.
Where to Use Bubble Wrap Insulation
Reflective insulation, like bubble wrap, requires dead air space to be effective. Some of the most useful locations include:
- Undersides of roof rafters in all types of buildings–house attics, garages, barns, storage buildings.
- Behind vinyl or aluminum siding. The air space is usually not one inch, but it is big enough to make the bubble wrap somewhat effective.
- Use bubble wrap insulation for walls in unventilated cavity walls.
- Recreation vehicles like motorhomes and campers.
- As a reflector close to heat-producing sources like stoves.
Bubble wrap remains an excellent packaging material–with or without foil wrap.
Where Not to Use Bubble Wrap Insulation
Don’t use bubble wrap anywhere that does not provide a dead air space of one-inch minimum. Without the air space or clear bubble layer, the R-value is zero. For instance, laying bubble wrap under a concrete floor before pouring it is a waste of time and money. Other applications where bubble wrap does not work include:
- Interior applications to stud walls tight to blanket insulation on one side and drywall on the other.
- Spray foam insulation that fills the entire stud cavity also eliminates the dead air space.
- Wood or cement board sidings that provide little or no air space.
- Between two solid surfaces, such as sheathing and rigid insulation board.
- Cold climate locations. Bubble wrap is counter-productive in cold climates because it reduces winter heat gain. All of Canada–for instance–is a cold climate location.
Bubble Wrap – Pros and Cons
Bubble wrap has some very good qualities and some not-so-good qualities. It also has some ugly going for it, which is covered in the next section.
- Helps keep buildings cool in hot sunny climates.
- Effectiveness is not affected by moisture or humidity.
- Easy to install, lightweight material.
- Does not degrade.
- Mold free.
- Pest free.
- Pricey. $0.25 – $1.00 per square foot.
- Ineffective in cold climates – may even be a detriment.
- Dust on the surface makes it ineffective.
- Can become an electrical hazard if in contact with live wiring.
Bubble Wrap Insulation Claims
Some manufacturers and salespeople have made extravagant claims for bubble wrap products and sold thousands of square feet at exorbitant prices. Some claims include:
- A 5/16” thick product will provide an R-10, a vapor barrier, and a radon barrier under concrete – not even close on all 3 claims.
- A ⅜” product has an R-value equivalent rating of R-5 to R-10. The product has an R-value rating of R-1.0. Period.
- R-value claims of up to R-16. Not close.
Bubble wrap can cost more than one-inch thick rigid board foam insulation, which has an R-value of R-5.0.
Yet, bubble wrap insulation is worth the cost when properly installed in hot climates. Attic space temperatures, for instance, should be close to the outside temperature. Radiant barrier bubble wrap can lower attic temperatures by up to 20 degrees F.–preventing excessive heat from migrating into living areas.
Do not expect miracles from this product. As noted, many claims do not live up to real-world applications. Don’t discount it either – bubble wrap insulation is very effective when used in the right situation.