Low-E Thermal Barrier Insulated Underlayment Installation

Low-e thermal barrier underlayment is a reflective, insulated roof underlayment made of reflective foil bonded to an insulating foam or polyethylene core. It installs beneath the roof covering and acts as a radiant barrier and thermal layer, reflecting solar heat away from the attic and reducing the temperature that reaches the roof deck and the space below. We stock and install ThermaSheet® low-e insulated underlayment.

Standard underlayment is primarily a water-resistant layer beneath the roof covering, while a low-e thermal barrier underlayment adds a reflective, insulating function on top of that. In addition to helping protect against water, it blocks radiant heat, which standard felt or synthetic underlayment does not do, so it actively improves the roof’s energy performance rather than just keeping water out.

An insulated, reflective underlayment lowers attic temperatures, reduces cooling costs, eases the load on your air conditioner, and adds a moisture and vapor barrier that helps resist mold in Florida’s humidity. Because it blocks radiant heat at the roof, it tackles the largest source of summer heat gain in a Florida home, complementing your attic insulation.

Reflective underlayment improves efficiency by stopping radiant heat before it enters the attic. A sunbaked roof radiates heat downward, and the reflective foil in a low-e thermal barrier underlayment bounces most of that radiant energy back, so the attic stays cooler, less heat reaches your living space, and your cooling system runs less. In Florida, where radiant heat dominates, that translates into meaningful energy savings.

Yes. Installed with an air space under tile or metal, a low-e thermal barrier underlayment can reflect up to 97 percent of radiant energy, and when installed directly under shingle or flat systems, it can reduce roof deck temperatures by more than 30 degrees. Cooler deck and attic temperatures are exactly what lowers a Florida home’s cooling load.

A low-e thermal barrier underlayment is a durable product designed to last the life of the roof system it is installed under, since it sits protected beneath the roof covering. It does not wear like an exposed surface, so once installed as part of your new roof, it continues to block radiant heat for decades.

The proper installation depends on the roof covering. Under tile or metal, we install it with an air space, often over battens, which lets it reflect up to about 97 percent of radiant energy, while under shingle or flat systems, it is installed directly to reduce deck temperature. In all cases, it goes over the base waterproofing underlayment and beneath the roof covering, installed to the manufacturer’s and your local code requirements.

They do different jobs and work best together. Traditional attic insulation resists conductive heat transfer and is rated by R-value, while a low-e thermal barrier underlayment is a radiant barrier that reflects radiant heat. Because so much of Florida’s roof heat gain is radiant, the reflective underlayment addresses heat that insulation alone does not, which is why we treat it as a complement to, not a substitute for, attic insulation.

Low-e thermal barrier underlayment is compatible with the major roofing systems, including tile, metal, asphalt shingle, and flat or low-slope membranes. The installation method varies by material, with an air space under tile and metal and a direct application under shingle and flat systems, and we install it correctly for whichever covering you choose.

Cost depends on the roof size, the roof covering, and the installation method, and it is typically included as part of a re-roof or new roof rather than priced alone. The most accurate way to get a number is a free inspection, after which we provide a clear, written quote, and we can note any current energy tax credit you may be eligible for.