Integrated siding and insulation wall system.
Progressive Foam/VIPCO Integrated siding and insulation wall system.

Two new products give vinyl siding a competitive edge by increasing its energy efficiency and enhancing its impact resistance. One product is an insulative foam underlayment, custom contoured to fit snugly behind hundreds of different brands and styles of vinyl siding. The other is line of vinyl siding products fused to a foam backing material, to create an all-in-one siding and insulation system. Progressive Foam Technologies, Inc. makes contoured foam underlayment under the brand name "Thermowall". The material is shaped to precisely fit behind nearly any manufacturer's siding profile sold in the United States. Installed over exterior walls just before placement of the siding, the underlayment provides a continuous solid backing that helps vinyl siding resist impacts that might otherwise cause cracks or dents. By adding an additional foam insulation layer, the R-values of exterior walls are increased by R-2.8 to 3.3, depending on the profile, not including the vinyl siding. The manufacturer states that the foam is made from environmentally benign expanded polystyrene (EPS), which has thermal expansion properties nearly identical to vinyl siding, and moderate vapor permeability to allow the siding to breathe.

Crane Performance Siding uses a similar concept to create lines of solid-core siding products including Craneboard and Techwall Plus. These products fuse a contoured polystyrene backing material to a vinyl exterior facing for a solid insulated wall system with an overall R-rating of 4 to 4.5, depending on the product selected. The manufacturer states that the product also helps to bridge wall irregularities, and interlocks tightly at seams to create a straight, solid finished wall appearance without the waviness sometimes associated with vinyl siding. The panel sections are up to18" high, covering nearly twice as much area as most vinyl panels, allowing installation to proceed more quickly. Application of insulative sheathing and exterior finish surfacing is accomplished in one step.

PATH Attributes

This siding adds another layer of insulation and moisture protection to the structure, helping to save on heating and cooling costs.

Both the foam underlayer and the solid core siding are made to fit most exteriors. Unlike conventional siding, the foam offers protection against dents and other impact damage, allowing the siding to remain aesthetically pleasing, functional, and lasting.

Ease of Implementation

Both systems are available through common distribution networks, but may not be carried as in-stock inventory items. Both manufacturers can provide lists of local distributors and qualified installation contractors.

Although specialty tools for cutting contoured foam backed insulation are not necessary, it makes the job a lot easier if the solid insulated wall system is cut with a hot knife. Special accessories, such as starter strips, shims, and corner posts, are needed for trim work due to the thicker profile of foam with insulation. However, these accessories are available from the manufacturer.

Foam products take up more space than conventional vinyl products alone, so slightly higher shipping costs may be incurred.

Initial Cost

The solid core siding systems ($181/sf) cost 30 percent more than conventional vinyl siding ($141/sf), or about the same as vinyl siding over 3/4 foam sheathing (R-4) ($189/sf).

Operational Cost

Not Applicable

U.S.Code Acceptance

ASTM standard D3679 is the industry standard for vinyl siding performance. The test measures four features of vinyl siding including its weatherability, impact resistance, ability to resist distortion from extreme temperatures, and product uniformity and dimensional consistency. Certified products are listed with the Vinyl Siding Institute.

Field Evaluations

Not Applicable


Both manufacturers provide installation instructions and accessories needed for most situations.

A starter strip is placed over building paper or house wrap to begin the installation of the Thermowall system. Then the first panel of vinyl siding is used to insure exact positioning of the foam underlayment. With the foam layer in place, fastening the siding proceeds according to the siding manufacturer's instructions. Special profiles are provided to finish corner and window areas.

Solid core siding products are installed much like conventional vinyl siding, except that the sections are larger. Corner and trim accessories are also available.


Crane offers a warranty for the life of the home against manufacturer defects and certain other conditions. For apartment and commercial buildings, this warranty covers a period of 60 years from installation.


Both systems provide the thermal insulation benefits of foam sheathing in a format that enhances the appearance and performance of vinyl siding. Exterior wall insulation is improved by R-3 or more, depending on the system and profiles chosen, with enhanced air-flow resistance and better sound control properties. Waviness is reduced and impact resistance is improved with solid support behind the entire siding surface. The Thermowall underlayment system provides these benefits in conjunction with any vinyl siding product chosen, while the Craneboard and Techwall systems allows installation of both insulative sheathing and exterior surfacing in a single step, saving labor costs.

The solid core siding systems ($181/sf) cost 30 percent more than conventional vinyl siding ($141/sf), or about the same as vinyl siding over 3/4” foam sheathing (R-4) ($189/sf).

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the U.S. Department of Housing and Urban Development (HUD/FHA), The Partnership for Advancing Technology in Housing (PATH), or any PATH-affiliated Federal agency or private company. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.