Oriented strand board (OSB), with a thin layer of low emitting aluminum foil fastened to ane side, is a mutual type of thermal-radiant-barrier sheathing. Foil-backed OSB is applied mostly in attics; however, it is too used in wall systems. The goal of a foil-backed OSB is to cool the air within the top layer of insulation in the attic or wall by emitting the radiant estrus absorbed through the roof or exterior walls, which reduces the Delta-T and lessens the overall free energy use in a building.

What is Delta-T?

Delta-T is the difference betwixt the temperature of the top layer of insulation in the attic or wall system and the living spaces. For example:

During the hot summer, the heat of the dominicus tin can heighten the temperature of the top shingles of the roof to nearly 180 degrees. The lesser of the roof deck will be 20 or 30 degrees lower.

Through the process of infrared radiation, the estrus from the roof is emitted (or radiated)  into the attic where the insulation absorbs it. When this occurs, the elevation surface of the insulation can accomplish a temperature of 130 degrees and more, which is much higher than the temperature in the living spaces (68-70 degrees). The Delta-T is the divergence in temperature between the peak layer of the insulation and the living spaces.

The foil layer of the OSB lowers the Delta-T because the foil is low emitting and does not emit or absorb heat. And so, when the sun hits the roof and radiates into the attic or wall, the foil layer of the OSB capsule reflects the rut to the roof or exterior wall, which keeps the summit layer of the insulation but a few degrees warmer than the outside air temperature. Similarly, when heat rises into an cranium during cooler months, the foil layer reflects it into the living spaces of a edifice. Without the foil layer, the OSB capsule volition blot heat and radiate it into the cranium space in the summer, or outside during the winter.

Adding more than attic ventilation will help, only not much. Fifty-fifty with excellent airflow in an cranium, the temperature of the summit surface layer of the insulation will only drop a few degrees.

5 Issues with Foil-Backed OSB Radiant Barriers

  1. The foil layer of the OSB lowers the Delta-T by reflecting the thermal energy due to radiation (lord's day'south heat) abroad from the insulation layer, which keeps the top layer of the insulation only several degrees warmer than the outside air temperature. However, foil-backed OSB often requires additional thermal insulation to prevent the transfer of thermal energy by conduction and convection.
  2. Only clean and shiny foil will emit rut. Dust and dirt brand the foil less reflective. Dirt and dust are specially problematic in attics where the foil-backed OSB is applied horizontally, which makes it decumbent to dust and dirt. It is crucial to keep the workspace clean when installing foil-backed OSB.
  3. Foil-backed OSB acts as a vapor bulwark, particularly when information technology is cold outside. If water vapor from the interior of the building moves into the cranium, and the foil-backed OSB is cooler than the dew point, the wet may condense on the underside of the barrier. When installing foil-backed OSB, builders must option a location where the barrier is unlikely to reach the dew point temperature.
    Condensation on the underside of foil-backed OSB tin can cause several problems:
    • If the insulation becomes damp, it will lose some of its insulating values
    • H2o spots may appear on the ceilings of the living spaces
    • Moisture tin can atomic number 82 to mold which is both unhealthy to the occupants of the edifice and tin can rot the ceiling framing or wall assembly
  4. For foil-backed OSB to perform correctly, builders must make certain there is an open air space next to the foil layer not less than ¾ -inch. If the foil-backed OSB comes in direct contact with other materials, like rafters and wall framing, heat will transfer through conduction from the foil-backed OSB to the adjacent materials. Ane reason contractors avoid using foil-backed OSB in wall systems is because it is hard to create the air gap needed for foil-backed OSB to work properly.
  5. The Oak Ridge National Laboratory constitute that roof mounted foil-backed OSBs may increase roof shingle temperatures by 2 to 10 °F.  Similarly, foil-backed OSBs installed on the cranium flooring may increase roof shingle temperatures by two°F or less. Unfortunately, higher roof temperatures may reduce the roof's service life.

Why Barricade® Thermo-Caryatid® S.I.B. is a Better Thermal Bulwark Than Foil-Backed OSB

Barricade Thermo-Brace Structural Sheathing

A better thermal bulwark to foil-backed OSB is Barricade Thermo-Brace® South.I.B. Specifically, Thermo-Caryatid® S.I.B, with conditions resistant barriers on both sides, is more moisture resistant and limits thermal conduction and convection more finer than foil-backed OSB. Importantly, the installation of Thermo-Brace® S.I.B saves builders time and labor over foil-backed OSB.

  • Thermo-Brace® S.I.B has high thermal resistance and low thermal conductivity, which makes it a good insulator because to inhibits thermal conduction.
  • A high-performing thermal barrier, like Thermo-Brace® South.I.B, is air-resistant and limits thermal convection.
  • Thermo-Caryatid® S.I.B saves coin over foil-backed OSB considering Thermo-Caryatid® South.I.B is lightweight and easier to install than wall application of foil-backed OSB, which saves builders labor and time.

Thermo-Caryatid® Southward.I.B. creates a superior thermal barrier compared to foil-backed OSB barriers. Barricade Thermo-Caryatid® S.I.B. has loftier thermal resistance and low thermal conductivity; both features essential to controlling air and moisture infiltration into a wall system.