The original, existing roof rafters are rather shallow, so to save material and ensure we have the maximum insulation value in the roof, we are using a soy based, open-cell, spray-foam insulation. Typical pink, batt insulation has trouble filling all framing cavities in a roof or wall which leads to air leaks and a sub-par insulation value. This can lead to large energy losses, in fact, up to 40% of energy loss can be attributed to unwanted air leakage, according to the Department of Energy.
By using spray foam all cavities can be filled to help minimize air leakage. The increased coverage and better performance of foam result in an insulation value of roughly R-4 per inch (for a total of R-30 for this project). Also, much less material is used since foam insulation expands to a ratio of approximately 1 to 120.
Best of all, the first cost difference between batt insulation and foam insulation are now practically nil, factoring in the improved energy performance of spray foam insulation will actually provide a cost savings within a year or two. Also, by utilizing an optimal insulating material we can further cut costs by reducing the size of mechanical equipment. Lastly, this particular foam insulation does not contain HCFC’s, off-gas formaldehyde, or volatile organic compounds, a vast improvement over batt insulation.