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Why Does CommTherm use Borate Formula Blowin-in Insulation?

Borates are a well known fire retardant in cellulose insulation that prevent flaming combustion, suppress after glow, and improve char formation, which tends to dehydrate the cellulose, forming protective glazes at the burning surface, should a fire ever start.
Borates also give protection to cellulose insulation (Siddiqui) against fungal (MOLD) and bacterial growth that the uninformed would expect it would support. Cellulose insulation is a good carbon source, has high moisture holding capacity, and a very large surface area for mold growth. But when treated with borates, cellulose becomes a flame retardant, mold inhibiting, high value insulation. This insulation passes numerous government controls and ratings that insure quality and consistency.

A number of studies have been conducted on the biological resistance of insulation materials. Grinda and Kerner-Gang tested insulation materials’ resistance to mold fungi and wood-damaging basidiomycetes. Their study concluded that mineral insulating boards and granular volcanic rock cannot be utilized by mold fungi but can be overgrown by them, while the foams they tested contained components that could be utilized by the fungi. This showed that untreated insulation materials (even those considered inert) could be affected and overgrown with mold. 

Viitanen studied the influence of insulation materials on wood biodeterioration. He concluded that insulation materials do influence growth of mold and decay fungi in contact with wood.

At high humidity, boron compounds added to the cellulose insulation fiber diffused into the wood and prevented growth of brown rot fungi. 

It was also shown that mineral wool (fiberglass) is destroyed by decay fungi, and at the same time actively supports surrounding timber decay. 

In most countries cellulose insulation materials are already treated with borates at high retentions to impart flame retardancy. Typical high commercial retentions of borate by weight (a combination of boric acid and/or borax) in order to meet national fire standards (Bower; §Siddiqui). 

Phosphates or sulfates are sometimes used as partial replacements for some of the borate, but probably should not be considered in warm humid environments for corrosion and fiber deterioration (Winandy, 2000). Ammonium sulfate, the most common replacement for borates is acidic, can corrode copper, may release ammonia gas under certain conditions of pH and temperature, and promotes fungal growth (Bower). 

We recommend using an all-borate additive cellulose insulation product. The inherent high R-value and low cost per "R" of cellulose insulation coupled with the mold inhibiting, insect repellent, and fire proofing qualities of Borates, makes this insulation option stand head and shoulders above the rest.

Speak to your insurance agent to see if using this insulation can reduce your liability payment, especially if you are fortunate enough to have a mold and fungi rider on the policy. The Association for Better Insulation is lobbying insurance industry agencies for special designations for this insulation to help reduce your insurance costs. Commercial Thermal Solutions donates a portion of each installation proceeds to ABI to help them in this cause. We appreciate your business.


§ Siddiqui, S A. A Handbook on Cellulose Insulation. Robert E. Kreiger Publishing Co., Inc. 23-33, 57-61. 

¤ Viitanen, H. Preservative effect of cellulose insulation material against some mold fungi and brown rot fungi Coniophora puteana in pine sapwood. Internat. Res. Groups on Wood Pres., Doc. No. IRG/WP/1484. 

¥ Grinda, M. and Kerner-Gang, W. Evaluation of the resistance of insulating materials to mold fungi and wood-destroying basidiomycetes. Mat. U. Org., 17, 135-156. 

± Bower, J G. "Borates and Cellulose Insulation – Partners in Quality Control". RSI Roofing, Siding, Insulation-Regulating Insulation (Special Report). Harcourt Brace Jovanovich, Inc.


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overview - large volume attics - soundproofing - fireproofing - home