Did you know…
...polymeric claddings, including vinyl siding, insulated vinyl siding and polypropylene siding, are some of the only cladding material categories that have been used extensively with insulation options?
Polymeric claddings on the market today meet current building codes, and insulated vinyl siding (a form of continuous insulation), in particular, is useful in meeting the 2021 International Energy Conservation Code (IECC) requirements. The IECC, often called the “energy code,” is the primary regulatory tool for energy-efficient residential construction.
The energy efficiency for many building materials is known as its R-value; the higher the value, the more efficient (or resistant to heat transfer) it is. Many cladding materials don’t have measured R-values that can increase the wall’s overall by at least R-2 and even up to R-3 or more, providing a substantial improvement in the energy efficiency of a home and a significant reduction in energy bills.
Continuous insulation requirements vary by climate zone and construction assembly. Beginning with zone 3 in the Southeast, and moving North, at least R-5 will be required as the 2021 energy code is adopted. In the Northern climate zones 5, 6 and 7, R-10 continuous insulation will be required. It’s essential to understand that products may be layered to reach these continuous insulation requirements. For example, if R-5 is required, you can use an R-2 insulated vinyl siding with an R-3 insulated sheathing to meet the code. See Climate Zone map below.
Climate Zone Map
| Climate Zone | Continuous Insulation Requirements |
|---|---|
| 3 | R-5 |
| 4, 5, 6, 7 | R-5 or R-10 depending on the wall insulation |
Cladding Weights and Opportunity
When constructing with continuous insulation, the building system expands and the cladding is typically pushed further away from the structural sheathing and framing.
This change is crucial as it affects how the claddings and trims are connected to the structural members. Cladding weights can impact the fasteners and can impact the potential need for additional nailable substrates called furring strips.
Polymeric claddings weigh between .5–1 lb. per square foot, whereas fiber cement products can weigh 3 – 5 lbs. per square foot, which can significantly impact how the product needs to be constructed and installed. Most siding calculations use the term square – a square is 100 square feet1
Chapter 7 of the International Residential Code provides specific installation requirements for the use of polymeric cladding with continuous insulation. In many cases, because of its lighter weight, polymeric claddings can be used over thicker continuous insulations without having to use additional furring strips (unlike fiber cement).
Reducing our Carbon Footprint
Choosing sustainability means choosing efficiency. And vinyl siding is efficient at every stage, from its resource-conscious manufacturing to its simple maintenance and onward to its easy recycling (where programs exist). Vinyl siding manufacturers are making steady and conscious progress at every step to lessen this material’s carbon footprint. In fact, our carbon emissions have decreased 15% over the life cycle of vinyl siding in the past decade. That’s 9.8 kg of CO2 per 100 square feet. And we continue to invest in meaningful progress with our members to help address global warming with resilient and sustainable building materials2.
VSI’s Product Certification Program
Insulated vinyl siding is tested in accordance with ASTM D7793 Standard Specification for Insulated Vinyl Siding, which includes a provision for thermal resistance, or R-value. Once products have been tested and an R-value has been determined, the R-value must
be displayed on the certified product packaging.
Insulated vinyl siding can be used to meet the R-value/U-factor energy code requirements.
Additionally, vinyl siding and polypropylene siding can be used with other types of continuous insulation, such as foam sheathing or fan-fold foam products, to help achieve energy code compliance.