The Easy Way to get R-15 Sidewalls

This month’s installment of the Building Science overview – Indoor Air Quality

In the June issue of the WABA Digest, two separate columns discussed some of the proposed changes to the International Energy Conservation Code (IECC), particularly in reference to wall insulation. As a reminder, the proposed changes are from R-13 to R-15 in 2×4 walls and from R-19 to R-21 in 2×6 walls. I have no intention of debating the merits of this change. Instead, I would like to point out that the easiest way to achieve higher R-values without switching to high-density batts or adding exterior sheathing: Certainteed’s Optima insulation, designed for use in the Blow-in-Blanket System, achieves an R-15 in 2×4 framing and an R-23 in 2×6 construction. The advantages of using Optima are numerous – no gaps or voids, no settling, plus it goes in the wall cavity completely dry. It also contains no chemicals that create noxious odors nor is it a source of food for insects or animals. One of the main concerns about raising the wall insulation R-values is about adding cost and using Optima does cost more than normal batt installations. But given estimates of changing to high-density batts or from 2×4 framing to 2×6 adding around $1,000 to the cost of an average new home, upgrading to the BIBS system with Optima adds less than half that. Plus, you still get all the benefits of having a better insulation job than just thicker batts can give you. Regardless of energy codes now or in the future, Optima may be a better choice to keep your customers’ homes more comfortable.