The Type of Sheathing Matters When Siding Your Home

The type of sheathing used beneath your siding is important. This is plywood.Many houses built today have some type of sheathing used underneath the siding. Sheathing is the material installed directly over the studs and interior insulation of a framed house. Typically sheathing is then followed by a vapor barrier material and then the siding of choice. Sheathing is one of the layers used in the siding of the home no matter the substrate used.

There are two main reasons to use sheathing: structural and non-structural. Non-structural sheathing improves insulation from heat, cold, and sound. Structural sheathing improves the building’s stability and keeps the wall from swaying or bending overtime. It also provides a base for the siding to be nailed into. Structural sheathing can also provide insulation from heat, cold, and sound.

Type of Sheathing Used on Older Homes

The year the house was built will dictate the most common type of sheathing used during the time. For example, in the 1970s and 1980s, a fiberboard sheathing material such as Celotex was used. Celotex is a black, fibrous material used for insulating against sound and heat. In the Denver Front Range today, homes needing new siding were typically built in the 70s and 80s and will have this type of sheathing present.

During this time frame the only options for siding were wood and aluminum. These substrates are not as heavy as others used today. A lighter type of sheathing was appropriate for the build then. Today, a stronger sheathing option is preferable to provide ample base for the heavier siding options. (While Celotex has become a structural sheathing option, it is primarily used in wood, plaster and stucco home applications.)

Today, the two most common siding replacement materials used in the United States are James Hardie fiber cement siding and LP SmartSide engineered wood siding. Both materials are offered in a pre-painted product; James Hardie Color Plus and LP Diamond Kote respectively. While engineered wood is relatively light like the wood and aluminum of old, fiber cement is heavier and will require a sturdier base to retain its shape over time.

At HRTI, we believe strongly that best practice dictates re-siding with a heavy-duty structural type of sheathing for James Hardie fiber cement siding. We prefer half-inch OSB (Oriented Strand Board) or 7/16-inch plywood anytime James Hardie fiber cement siding is being installed. Due to the weight of the product, the potential for missing a stud during hanging, though rare, can occasionally happen.

A missed stud can result in a situation where overtime the fiber cement siding can sag and break from its own weight. Due to this, we strongly recommend the installation of a heavier structural type of sheathing to eliminate this issue all together. The half-inch OSB or 7/16-inch plywood both fulfill that need. Missed studs become a non-issue when there is more to hammer the siding into than studs placed 16 inches apart.

At HRTI, we love and recommend both James Hardie fiber cement siding and LP SmartSide engineered wood siding and regularly install them in our exterior renovations. We find engineered wood is a better fit on the Front Range (LP), while fiber cement siding works better in the mountain communities (James Hardie). Both options provide stunning results and come in a range of colors and style options.

James Hardie fiber cement siding works well in mountain communities as it is fire resistant and well-suited to high wind areas. It’s virtually indestructible. LP SmartSide engineered wood siding is more popular amongst the Denver Front Range communities. It is easy to install, easy to maintain, and therefore very cost effective.

The type of sheathing that is right for your next project is wholly dependent on your choice of siding. Contact HRTI today for a free, no obligation consultation to determine the best siding options for your home.

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