Problems with icynene foam insulation

moth image by Wong Siew Tung from

Building insulation improves its energy efficiency and comfort by maintaining an optimal temperature within the structure. Icynene foam is a liquid plastic that is popularly used as a structural insulating material.

The foam is injected or sprayed in walls with a low-volume applicator, where it expands within minutes to fill all cavities and voids. Icynene insulates against sound and provides an effective nontoxic air seal. The material, despite its widespread use and advantages, is associated with some problems.


Icynene foam insulation is easily penetrated by insects, including carpenter ants, moths and termites. Insects damage the structural integrity of foam insulation. The insects reduce the insulation's effectiveness and lower its thermal performance. Moths, including gypsy moths, burrow in the soft sponginess of the material and degrade its dimensional stability. Icynene foam insulation typically requires additional chemical or mechanical treatments to improve its resistance to insects.

Mold and Dust

Icynene foam insulation is susceptible to mould and mildew. Excess water in the chemical make-up of the insulation and moisture in the environment further lowers the resistance of the insulation to mould and rot. Icynene foam insulation tends to accumulate dirt and dust within its air pockets after extended periods, which harbours dust mites and may prove problematic for allergy-prone individuals.

Airtight Sealing

Icynene foam insulation provides a nearly airtight sealing. Houses insulated with the material are caulked and may require additional ventilation in the winter months.


Icynene foam insulation is typically more expensive than loose-fill or batt insulation. Buildings fitted with the material may require installation of advanced ventilation systems to ensure that all loose particles are effectively filtered out and a constant flow of fresh air is maintained, which hikes the cost further. According to, as of September 2010, expect to pay between 80p and 90p to insulate a square foot of wall and between £1.0 and £1.20 to insulate a square foot of roof decks with Icynene foam insulation.

Excess Insulation

Icynene foam application is messy and entails a lengthy cleanup process. The material expands after it is applied, often overfilling cavities and crevices. Its great expansion rate warrants that all excess insulation is trimmed off with a sharp knife or hand saw. Although not a considerable problem, trimming laborious when working with large areas or rooms.

No Fire Resistance

According to Richard T. Bynum in the "Insulation Handbook," Icynene foam insulation offers no resistance in the event of a fire. Although the material itself does not contribute fuel to fire, the insulation will burn completely if exposed to burning flames for more than 15 minutes. Cover Icynene foam insulation with an appropriate thermal barrier, such as a gypsum board, to improve fire resistance.