foam insulated sheathing for exterior walls

Sheathing the exterior walls of your home with foam panels (foam insulated sheathing) is a great choice for energy-efficiency. And you have two main options in this case: use simple foam panels (and plywood, OBS or othe similar sheathing material, to get structural strenght) or use what's is often called structural foam sheathing.

Exterior Wall Insulation

Simple wall cavity insulation is important but often insufficient to provide high comfort and energy-efficiency to walls and homes. In colder or even in temperate climates, cavity and solid exterior walls should also benefit from a continuous layer of insulation (insulated sheathing) in their surfaces.

Only that continuous layer prevents thermal bridging: the unwanted bridging of heat or cold trough the wood and steel studs, pipes, ducts and other similar elements in the walls...

See: Wall Insulation.

Simple Rigid foam Panels sheathing

Foam sheathing (rigid foam panels, made from molded polystyrene, extruded polystyrene and rigid polyurethane and polyisocyanurate) is excellent for that task of covering the exterior walls.

Foam sheathing proviedes an high insulation value, overcoming the lack of insulation value of traditional sheathing solutions. See: Rigid foam insulation.

The problem with simples rigid foam sheathing is that it doesn't provide by itself enough structural strength to resist to wind, rain and other natural loads; and they are not a good fastening base for siding: nails, staples and other mechanical fasteners may easily tear the insulating panels.

Structural Foam Sheathing

To overcome foam sheathing limitations, some manufacturers (very few: Dow is a pioneer and the best known) are offering structural foam insulated sheathing panels.

Structural Foam Insulated Sheathing advantages

But what are they?

Dtructural foam insulated sheathing panels comprise - in one single and light-weight product – not only the higher insulation value of rigid foam panels but also structural strength and moisture-resistance, simplifying the construction and allowing labor savings.

Typical structural wall insulating sheathing products combines three main proven sheathing materials: 1) polyisocyanurate foam sheathing (a typical rigid foam panel), 2) structural laminated fibrous board (to provide structural strength to the mix) and also 3) special facings to resist the effects of water and other natural loads.

Structural foam insulated sheathing eliminates the needs to install separate layers of building wrap or felt paper (to block rain and air infiltration) as well as plywood or other structural strengthening materials.

The material is rigid and impact-resistant, supporting a long-lasting building, and has an excellent insulation performance. And since it is an all-in-one product application, it provides significant labor savings.

Costs

Structural insulating sheathing is significantly more expensive than common sheathing with plywood, OSB or other traditional sheathing options. And also more expensive than plywood (or OBS or...) sheathing combined with rigid foam insulation panels (in this case the difference of prices depends largely on the exact type of rigid foam and its density and insulation value).

Environmental impact

Foam insulated sheathing products are energy-efficient solutions and, due to it, eco-friendly solutions. And since they can use a large content of recycled material they become even more eco-friendly.

See: Environment & Insulation Materials.

Installation

Structural foam insulated sheathing products involve the techniques and tools of common wall sheathing.

Panels are typically installed with nails spaced 3 inches along edges. Fasteners and pneumatic tools should comply with the manufacturer's specifications.