What is rigid board insulation?

Insulation made from either foam plastics or fibrous materials and is manufactured in standard-sized sheets. It’s resistant to moisture and fire and has a higher R-value per inch thickness compared to traditional fiberglass insulation.

Does polyiso foam board insulation need a vapor barrier?

Foam board insulation does not require a vapor barrier but rather taped or sealed at its seams, and spray foam applied in all the corners.

Does polyiso foam board insulation absorb water?

Polyiso foam board insulation is manufactured with a closed-cell structure, making it extremely waterproof and suitable for areas prone to moisture.

Is polyiso foam board insulation fire resistant?

Polyiso foam board insulation is highly fire-resistant and has a temperature resistance of more than two times of other building insulation foams.

What are the advantages of polyiso foam board insulation?

Polyiso foam board insulation has the highest R-value compared to other types of insulation. It’s resistant to fire and moisture, will maintain its physical characteristics across a wide range of extreme temperatures, and its lightweight and sizing make it easy to handle.

How long does Polyiso last?

In general, foam board insulation has a lifespan of 100 years or longer.

What are the disadvantages of polyiso foam board insulation?

Some polyiso foam board insulation contains harmful hydrochlorofluorocarbons that are known to be potent greenhouse gases. Although it has one of the highest R-values, some of its thermal performance can deplete within a couple of years or as temperatures decrease. Each panel must be installed airtight; otherwise, air will infiltrate the gaps, and it will be less effective.

Learn about Polyiso Rigid Board Insulation

Polyiso rigid board insulation is made of polyisocyanurate foam, a closed-cell foam with a very high insulation value of R-6 to R-6.5 per inch. It can also be made into structurally insulated panels or foamed in place.

Polyiso insulation boards and structural panels can be used for wall sheathing and roofs. Look for products that use low-toxicity flame retardants like TCPP or better - some are even free of TCPP.

ASTM test methods for determining the R-value of a material at a mean temperature of 75°F. Unlike extruded polystyrene (XPS) and expanded polystyrene (EPS), polyiso performance degrades as temperatures dip. As an example, extruded polystyrene (XPS) is rated at R-5 per inch, yet out performs polyiso rated at R-6 in climates below 50°F. This is due to the condensing of trapped blowing-agent gases that can occur at cold temperatures. While the product performs well in warmer climates, it may not in cooler climates. You should also avoid using polyiso in damp climates due to its lack of permeability.

Polyiso is considered one of the most environmentally friendly types of rigid foam board, because it has a high insulation value and typically does not the high global warming potential HFC blowing agents in its manufacture. Many brands also use relatively low-toxicity flame retardants such as TCPP.