Homasote. 440 SoundBarrier is a nearly 100% recycled nailable structural board made from cellulose fiber, with an insulating value of R-1.2 per 1/2 inch. Originally intended as a soundproofing product, the firm says it withstands jobsite weather and mistreatment better than standard, impregnated fiberboard, and offers shear strength sufficient for many exterior wall-bracing applications. 800.257.9491. www.homasote.com.