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Sheathing Options for Contractors

New Home Construction with Sheathing

Depending on local codes, sheathing is often added to new walls and roofs to add strength and boost insulation. In addition, sheathing is used for as a nailing base for siding. Basically, there are two types of sheathing: structural and nonstructural.

Structural Sheathing for Exterior Walls

Zip Sheathing being installed on a houseStructural sheathing is a critical component of a structure’s framing. It adds rigidity and ties together all of the wall studs. However, this type of sheathing doesn’t provide any noteworthy insulation value to the structure. The most popular structural sheathings include gypsum board, oriented strand board, plywood and wafer board. These structural sheathing materials should be rated and have the right thickness.Although panels are available as thin as 5/16 inches, it’s better to opt for the sturdier panels that are ½ inch. It costs a little more but is worth the investment with more strength. Galvanized nails should be used and spread apart as indicated by local building codes.

Nonstructural Sheathing for Exterior Walls

While this type of sheathing doesn’t provide significant strength for walls, it does add insulation value. Most of the nonstructural sheathing is made with polyisocyanurate or polystyrene. When compared, polyisocyanurate offers more insulation per inch with values up to 8.7 per inch. This type of sheathing comes in either cellulose-fiber panels or rigid foam panels and is attached directly to masonry walls and wall studs. It’s also applied over or under structural sheathing. Standard panels come in 2’ by 8’, 4’ by 8’ and 4’ by 9’.  It also comes in ½” and ¾ “ thicknesses.

Deciding on which type of panels to use is dependent on the type of siding and walls. Panels with matte facings or reflective aluminum are often used under wood, stucco and brick sidings. Non-foiled panels are recommended for underneath wood, vinyl and aluminum sidings.

Roof Sheathing

Zipsystem roofToday, there are roof sheathing systems that are engineered with energy-efficient barriers to reduce air seepage and keep water and moisture out. This type of sheathing is often made of engineered wood for strength and durability. Built-in vapor permeable water-resistive barrier eliminates the use of felt and house wrap, which are a hassle to work with. These roof sheathing systems are easy to work with. Just install the panels and tape the seams.

Long Length Sheathing

Long length sheathing comes with many advantages. It reduces the number of horizontal joints and the need for blocking. There are many companies on the market that make long length sheathing that also offer an excellent air barrier and superior moisture protection. Go vertical with long length sheathing and eliminate the need for house wrap. Contractors can find long length sheeting in different sizes to suit every job.

Insulated Sheathing and Foams

The types of foams used in insulated sheathing are thermoplastics and thermosets. Thermoplastics feature non-cross linked polymers and do melt at high temperatures. In addition, thermoplastics may degrade when in contact with some adhesives and paints. It’s important to use thermoplastics only when approved by the manufacturer that the material is compatible with these types or organic solvents. The most common thermoplastic foams used in the construction industry are XPS and EPS. Thermoset plastics are based on cross liked polymers and do not feature a melting range. The most common thermoset foam on the market today is polyisocyanurate. It has strength and is fire resistant.

The thermal resistance of these products vary. Overall, polyisocyanurate has the best R-value per inch, EPS foam has the lowest R-value per inch and XPS is a little more efficient than EPS foam. The thermal resistance of these products remains stable over the long term.


Extended Exposure Sheathing CTA

Photo credit: bk1bennett / Foter / Creative Commons Attribution-NoDerivs 2.0 Generic (CC BY-ND 2.0), Huberwood.com

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Wallboard Supply Company is a third generation, family run business that has been serving New England's building needs since 1970. Bob Filion started the company with a commitment to provide quality drywall and finishing products with unmatched customer service. The company has grown over the years, expanding its' product range, but never wavering from its' core values.