Polyiso Insulation for Home Renovation

Polyisocyanurate Foam Insulation – A Renovation Weapon to Combat Rising Energy Costs

polyiso1During most renovations, people tend to focus on the design of the home and its most noticeable features, such as light fixtures, countertops, and wall colors. Given the rapidly rising price of energy in the United States, those considering renovation work may want to turn their attention to a less glamorous, but more effective, target—insulation.

As many design professionals are well aware, choosing energy efficient insulation can be one of the most effective ways to save energy and money. Adding or exceeding the recommended levels of insulation during renovation can lower energy consumption and reduce utility costs while enjoying the strong possibility of a payback upon project completion. Architects and builders should assume the role of not only specifying the best insulation package for each project but also educating homeowners.

Specifying Polyiso insulation

Polyisocyanurate (Polyiso) insulation is an excellent choice for a variety of renovation applications because of its excellent energy conserving qualities. Polyiso foam has a high R-value per inch, which helps reduce energy costs for the homeowner over the life of the building—an especially important factor considering the expected sustained rise in fuel costs.1

Polyiso insulation is a thermoset, closed-cell, rigid foam plastic insulation manufactured in board form. Via a continuous lamination process, liquid raw materials that expand and become light (yet strong) are applied between engineered facing materials. These facings provide strength, improve rigidity, and enhance thermal performance. Polyisocyanurate board insulation is most commonly supplied as 1.2-x-2.4-m or 1.2-x-2.7-m (4-x-8-ft or 4-x-9-ft) sheets in various thicknesses.

Polyiso foam boards are available in a range of compressive strengths, meeting various marketplace requirements. Compressive strength refers to the ability of a rigid foam plastic board to resist deformation and maintain its shape when subjected to a force or load. Common construction applications require compressive strengths adequate for polyisocyanurate to maintain its shape during installation, as well as during use.2 ASTM International C 1289, Specification of Polyiso Insulation, mandates all polyisocyanurate products have a minimum stated compressive strength of 110 kPa (16 psi). Practically speaking, wall applications require polyiso to support flexible siding materials; for roofing projects, it must withstand limited installation traffic, support fastener loads, and sustain the total roofing system.

Polyisocyanurate insulation can contribute to a more fire-safe home or building after renovation work. It passes both American National Standards Institute/Underwriters Laboratories Inc. (ANSI/UL) 1256, Fire Test of Roof Deck Constructions, and Factory Mutual (FM) 4450, Class I Insulated Steel Deck Roofs, without a thermal barrier. Additionally, polyiso foam insulation stays intact during fire exposure in ASTM E 84, Standard [Tunnel] Test Method for Surface Burning Characteristics of Building Materials, forming a protective char layer and remaining in place to meet building code requirements.

Polyisocyanurate for renovations
Adding polyiso sheathing in the renovation of houses and buildings can be inherently more energy-efficient due to the plastic material’s thermal properties. Typically, polyisocyanurate is used to insulate the entire wall (including the framing), thereby significantly reducing heat loss through both convection and conduction. Additionally, properly insulating a structure with Polyiso foam insulation can decrease condensation in the walls, potentially lowering moisture-related problems.

When properly specified and installed, polyisocyanurate insulating sheathing can be one of the best values available for those upgrading or renovating a home or facility.

Polyiso for Exterior Insulation
When re-siding a building, vinyl siding can be placed over a layer of polyiso installed atop the existing exterior cladding. Polyisocyanurate can also be used with exterior products such as fiber cement siding, wood siding, stucco, and metal siding.

Polyisocyanurate Foam for Interior Wall Insulation
For interior wall refinishing projects, a layer of polyiso insulation can be installed prior to the addition of new gypsum wallboard.

Basement Insulation
Non-insulated basement walls can be a significant source of heat loss. When finishing a basement, a layer of polyisocyanurate sheathing can be placed over the interior wall and covered with 13-mm (0.5-in.) gypsum board to insulate and upgrade the basement to a more comfortable space.

Insulating Attics With Polyiso Foam
When turning an attic into a living space, one can place Polyiso on the interior over the studs before installing gypsum board. It can also be practical to fill the cavities with polyiso insulation.

Home-Addition Insulation
Should the renovation include adding square footage to the home, such as a new family room or master bedroom, using polyisocyanurate insulation as the exterior sheathing can provide the homeowner with energy-efficient construction and potentially add to the long-term thermal performance of the entire home.