|Ask Norm: Why Not Use Fire-Rated Drywall?|
David: Question: Why don't builders use 5/8-inch fire-code drywall throughout the entire house? I'd certainly pay a premium over standard drywall to have a more fire-resistant structure.
—Steve Miller, Sylvan Lake, MI.
Norm Abram replies: The 5/8-inch, "fire-code" drywall (called Type X) increases a wall's fire rating to a minimum of 1 hour, from the 30-minute rating for standard ˝-inch drywall. And it's not just thickness that makes the difference. Type X has a denser core and contains glass fibers that keep it from crumbling in the heat. But because Type X is slightly more expensive-about 75 cents more per sheet—it's rarely used in residential construction except where the building code requires it—on
walls separating an attached garage from the house, and around the boiler in multiple-family dwellings. If you're willing to shell out the extra dough, you certainly could use Type X throughout a house, yet it won't necessarily be safer. You’d also have to close off all the other pathways for fire to travel-open doorways, non-fire-rated doors, walls without fire blocking-and that could get costly and look ugly. Type X does have another often-overlooked virtue: it dampens sound transmission through the walls. Do you have teenagers?