Roof cooling with reflective insulation

Reflective insulation main goal is to help keep the roof and the attic cooler. And that by reflecting the sun's heat and by blocking their entering into the house.

Reflective insulation is mostly used in hot climates and is often a simple shiny aluminum foil laminated onto plastic or paper. That foil is often known as a radiant barrier, or a RFL (Reflective Foil Laminate).

Energy savings For hot and cold climates

In hot climates, radiant barriers can lower cooling costs significantly. Savings between 5%–10% in cooling bills are often reported.

VAPOR BARRIERS VS. RADIANT BARRIERS
Do not confuse Vapor Barriers with Radiant Barriers. While Radiant Barriers materials intend to prevent the sun's heat and are mainly applied in exterior surfaces or on surfaces giving access to them, Vapor Barriers are materials used to seal the interior living spaces from indoor moisture.

In cold climates, reflective insulation is much less interesting, even in attics and ceilings, where it is more cost-effective to install high levels of common insulation (fiberglass, sprayed foam, cellulose, rock wool materials).

Reflective insulation materials

There are three main types of reflective insulation (radiant barriers):

- RFL sheets (sarking);
- RFL concertina, and
- RFL bubble-form.

RFL bubble-form insulation are used in irregular or obstructed places. RFL sheets and concertina-type materials are used in more standard spaces, typically between studs joists and beams of ceilings, or walls and floors.

Uses

Reflective insulation is mainly used in attics and ceilings, to help keep the roof cooler, by stopping the sun's heat. But it can also be used in cavity walls and around door openings, water heaters and pipes.

A do-it-yourself job

Reflective insulation is fairly simple to install either in new or existing homes. Materials are lightweight, clean, non-toxic and easy to handle.

There are, anyway, some details that can be important. Just pay attention to the manufacturer’s instructions and to basic safety precautions. Also check fire and building codes. And do not forget that a poor installation will mean a lower performance. Reflective Foil for roof cooling

Roof Cooling Installation

The simplest way to install reflective insulation in roofs (to make them cooler) is to lay the reflective insulation directly on top of existing attic insulation, with the reflective side up.

But this isn't the best option due to potential problems with moisture (even in perforated radiant barriers) and dust accumulation. Reflective Foil Insulation for roof cooling

A far more efficient alternative is to install the reflective material between the roof sheathing and the attic floor insulation. Many radiant barriers are placed at the top cord of trusses or draped over them.

The schemes below, from RIMA (Reflective Insulation Manufacturers Association), show two common and efficient methods for "roof cooling".

In the case of foil-type barriers, the radiant barrier and the bottom of the roof should be separated by a small gap (1.0 inch/2.5 cm), to get ventilation and also for a better efficiency.

Warranties

Reflective insulation warranties vary with manufacturers, but they do not mean much: they all are typically very resistant to harsh conditions and long lasting.

Costs

Radiant barriers prices of 15–70 cents per square foot are common. Some hybrid products combining thermal insulation with reflectivity properties are more expensive.