Structural Sheathing vs. Nonstructural Sheathing

zipsystem r sheathing

The majority of newly constructed walls need sheathing; nonstructural sheathing is an insulator, thus increasing the R-value of a home, whereas, structural sheathing offers additional strength to the frame of a home. Sheathing is also easy to handle and is the perfect underlayment for installing new siding.

An existing wall does not always require sheathing; however, sheathing is used on an existing wall if old siding is removed and then replaced with a style of siding designed to have sheathing as its base.  

Structural Sheathing

Common Forms of Structural Sheathing

  • Wafer board
  • Plywood
  • Exterior gypsum board
  • Oriented strand board (OSB)

Structural sheathing attaches wall studs to one another, which contributes to the strength of a home’s framing.

Structural sheathing offers a nailing base for the installation of siding. It is important to note that the majority of structural sheathings will not add a significant amount of insulation value to the home.

New Home Construction with SheathingThickness

Structural sheathing is available in various thicknesses and sizes. While you can purchase a panel as thin as 5/16", consider spending a little more and purchasing the 1/2" panel. The 1/2" panel offers the home a significant amount of additional strength when compared to the 5/16" panel.

Panel Sizes

While the 4' x 8' panels are the most common size of structural sheathing that is used, some sheathing materials are also available in 4' x 9' and 4' x 10' panels.

Nonstructural Sheathing

Common Forms of Nonstructural Sheathing

  • Polysiocyanurate
  • Extruded Polystyrene

Nonstructural sheathing will not add a considerable amount of strength to a home’s walls; however, this type of sheathing can drastically increase the insulation (R-value) of a home.

Cellulose-fiber and rigid foam panels can be attached to masonry walls and placed over existing siding (prior to re-siding a home). These panels can also be attached to wall studs and on top of or underneath structural sheathing.

Polysiocyanurate vs. Extruded Polystyrene

Polyisocyanurate offers a substantially higher per-inch insulation value (R-value) than polystyrene does. The R-values of polysiocyanurate are as much as R-8.7 per inch higher than its polystyrene counterpart.

insulfoam insulwall insulationFoam-Board Thickness

The thickness of foam-board ranges from 3/8" to 4 1/4". Generally, the best foam-board thickness to cover existing siding is the 1/2" and 3/4".

Panel Sizes

The standard foam-board panel sizes are 2' x 8', 4' x 8' and 4' x 9'; however, some foam panels are available in lengths of up to 50'.

Exterior Gypsum Board Sheathing

Some types of sheathing have paper mats. These mats can be problematic in that they can mold and/or mildew. For this reason, exterior gypsum board has fiberglass mats instead. These fiberglass mats are designed to resist mold and mildew.

Choosing Nonstructural Panels

The kind of panel used depends greatly on the materials used to construct a home's walls, as well as the type of exterior siding being applied.

Choosing the Correct Type of Nonstructural Panel

Panels that have matt facing or reflective aluminum panels should be applied beneath:

  • Stucco
  • Brick
  • Some of the sidings constructed of wood

Non-foil-faced panels are usually applied beneath:

  • Vinyl
  • Aluminum
  • Wood-based sidings

At the Wallboard Supply Company, we take pride in all that we do. Our staff is dedicated to helping customers in any way they can. Whether you just have a question to ask or need assistance with an order, we are here to help make your project run as smoothly as possible. Contact one of our Wallboard Supply Company locations today so we can help you complete your project in an efficient and timely manner.

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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.