structural foam insulated sheathing

The insulation of wall cavities (the gap between the two layers of most walls) is important but not sufficient, since it doesn’t prevent unwanted losses or gains of heated or cold air (thermal bridging) through wood studs and other wall structures.

Sheathing the walls with a continuous structural foam insulation layer is necessary to higher energy performance. Structural wall insulating sheathing is the best response to that goal.

Simple foam sheathing limitations

Foam sheathing is excellent in terms of insulation, but simple foam boards do not provide enough strength to resist to wind and rain and other type of loads in typical homes. And simple foam sheathing doesn’t provide a sufficiently strong fastening base: nails, staples and other mechanical fasteners may easily tear the insulating panels, compromising the building integrity.

On the other hand, wood panel sheathing (and most sheathing options) do not provide sufficiently insulation and energy efficiency.

Simple vs. Structural Foam Sheathing

To surpass simple foam sheathing limitations, manufacturers are offering structural foam insulating sheathing panels. These panels embody - in one single and light-weight product – not only higher insulation but also structural strength and moisture-resistance, simplifying construction and allowing labor savings.

Composition

Structural wall insulating sheathing products combines two proven sheathing materials: polyisocyanurate foam sheathing and structural laminated fibrous board.

Advantages

Structural wall insulating sheathing eliminates the needs to install separate layers of building wrap or felt paper (for rain or air infiltration barrier) as well as plywood or other structural strengthening materials.

The material is rigid and impact-resistant, allows long-lasting buildings and has an excellent insulation performance (R-3 for standard thickness; more, for thicker panels). Furthermore, it fits together with standard window and door jambs.

Structural insulating sheathing also simplifies wall construction with significant labor savings, mainly associated with a one single product application instead of two or more.

Disadvantage & Costs

Structural insulating sheathing is more expensive than common sheathing with plywood, OSB and other wood based options (or fiberglass and other fibrous boards).

However, since structural insulating sheathing provides a single-layer product with high insulation performance, capable of resisting to air, moisture and other loads, if you want to get all these features with separate products, then structural foam sheathing becomes competitive. But all depends on the thickness and type of solution.

In most cases, it’s on the long run that structural insulating sheathing becomes highly advantageous (through energy savings).

Environmental impact

Besides being environmentally-friendly due to the energy-efficiency of the walls and homes built with it, structural insulating sheathing may contain a large content of recycled material, which is also environmentally-friendly.

Installation

Structural insulated sheathing products demand the common techniques and tools used for the installation of common wall sheathing. Panels are typically installed with nails spaced at 3 inches along panel edges. Fasteners and pneumatic tools should comply with the manufacturer specifications, which are also very important for panel joints: they should be taped and properly integrated with windows, doors or flashing.