A.Architect Jerry Germer responds: There is little if any difference between fiberglass sound-control batts and unfaced fiberglass thermal batts. Owens Corning’s published R-values for their 3 1/2-inch-thick thermal batt insulation and their sound attenuation batts are identical at R-11. An Owens Corning representative says that the two products are tagged differently mainly for marketing purposes. CertainTeed’s 3 1/2-inch sound-control batts also come in at R-11. According to a representative of Schuller International, their sound-control batts are slightly less dense than their thermal-control batts. While their 3 1/2-inch sound-control batts achieve R-11, their thermal batts in the same thickness are rated at R-13 and R-15.

In most cases, sound-control batts are priced the same as comparable thermal batts. But if you can find thermal batts at a lower price than sound-control batts, there is no reason not to use them for sound control.