Installation

Faced Insulation

These basic techniques can be used for many different areas where you will be installing faced fiber glass insulation.

Inset stapling:
• Place the insulation in the cavity and check to be sure it completely fills the cavity, top to bottom.

• Be sure that each sidewall batt is butted closely to the next one before fastening. Gently press the insulation at the sides into the framing cavity, until the outside edge of the stapling flange is flush with the face of the framing.

• When inset stapling insulation between framing members, start stapling at the top and work down. Use enough staples to hold the insulation firmly in place (about every 8") and avoid gaps and fishmouths between the flanges and framing.

Face stapling:
• Place the insulation between framing members and check to be sure it fits the cavity at both ends. With facing material flush to the face of the framing, the flanges will overlap the framing. Staple the flanges to the face of the framing, using enough staples to hold the insulation firmly in place to avoid gaps and fishmouths.

• The flange of the faced insulation placed in the next cavity will overlap the previously stapled flange. When more than one batt is used, pieces must be snugly butted.

• To install faced products by pressure fit, gently place the insulation into the cavity space between framing members. Make sure the insulation facing is flush with the face of the stud. The insulation must fit snugly at the sides and ends.

• Some CertainTeed products, such as EZR and SpeedyR, which do not need to be stapled, are produced without stapling flanges. 

• For some warm and humid areas, such as Florida, the Gulf Coast and Hawaii, the vapor retarder should generally be installed facing the outside. Check local building practice and/or building codes to be sure. Do not install a continuous vapor retarder, like polyethylene, because there may be times when the weather becomes cool, you heat your home, and water vapor then moves from the interior toward the exterior. In this situation, a discontinuous vapor retarder such as pre-attached facing on insulation will retard the passage of vapor, yet allow some water vapor to pass. This helps prevent moisture build up in the wall cavity and decreases the potential for condensation.

• Vapor retarders are not a standard recommendation for attics. Except for very cold regions and in isolated cases where there is high humidity in the house during the winter, attic vapor barriers aren’t required provided the attic is sufficiently ventilated (as a rule of thumb, one square ft. of vent opening is needed for every 150 square ft. of ceiling).

• If installed in an attic, a continuous vapor retarder is usually used to reduce air infiltration. If this is accomplished and a similar air infiltration retarder is installed in sidewalls, mechanical ventilation such as a heat recovery ventilator should be installed to prevent trapping air pollutants and moisture within the house. Moisture build-up can cause mildew on the walls and ceilings.

• In other warm, humid regions, especially southern coastal areas with a long cooling season and high exterior humidity, air conditioning causes continuous moisture flow from the exterior toward the interior cooled area. If a vapor retarder is used, it should be on the exterior of the wall. However, it should not be a continuous air/vapor retarder such as polyethylene. The reason is that there may be times when the weather becomes cool and vapor movement reverses and moves from the interior toward the exterior (winter condition). When this happens, it is best to have a discontinuous retarder such as that provided by faced fiber glass insulation to retard the passage of vapor, but permit some vapor to pass. This helps prevent moisture build-up in the wall cavity and decreases the potential for condensation.

• In some areas of the South, it may be difficult to determine where the vapor retarder should be placed. Where there is uncertainty, it is best to follow local practice and local codes. In either case, for reasons mentioned above, only a discontinuous vapor retarder should be used.

• Never leave faced insulation exposed. The facings on kraft-and foil-faced insulation will burn and must be installed in substantial contact with an approved ceiling wall or floor construction material.

• Flame-resistant foil (FSK-25) is the only insulation facing that can be left exposed.

• Separate vapor retarders are used in some constructions. They should be installed to the warm-in-winter side of framing. A 2-mil  nylon film (MemBrain^TM, the Smart Vapor Retarder), available in rolls, is rolled out horizontally and stapled to the face of the framing. It is recommended that the vapor retarder be stapled at the sides and the excess material folded back into the room. If more than one sheet of the retarder is required, a double fold should be made at the meeting of the two pieces and stapled, or the sheets may be overlapped and taped. The pieces, if stapled, should meet only at a stud or a joist.

• Cover the retarder with gypsum drywall or other approved interior material, as required by local codes, as soon as the insulation and vapor retarder has been installed. 

In an attic, installation of blown-in insulation includes these steps:

• Run a hose from the blowing machine through any available attic opening.

• Blow insulation in the direction of the joists, keeping the hose close to the floor. 

• To achieve the desired R-value, the insulation must be installed to the manufacturer's recommended minimal thickness using the recommended number of bags.