Unvented Roof Insulation Mineral Wool

Prior to the completion of research and publication of the 2018 irc concerns about condensation in warm humid climates prevented the practice.

Unvented roof insulation mineral wool.

If you choose or need to go with an unvented roof you would need either exterior insulation or a flash coat of closed cell spray foam first then you could round out the insulation package with mineral wool. Air permeable insulation such as fiberglass batts dense packed cellulose or blown in fiberglass can t be used alone for an unvented assembly since these types of insulation can allow moist indoor air to reach the cold roof sheathing leading to condensation or moisture accumulation. Building unvented attic assemblies with fiberglass and mineral wool. Our new guide details how to do this.

That s a brief answer. Mineral wool has an r value comparable to spray cellulose or high density fiberglass batts. If you have an easy roof to vent and decide to go that route you could use mineral wool insulation between the rafters and beneath the vent channels. This option gives builders an alternative to using spray foam insulation while providing the ability to use cost effective easy to install air permeable insulation systems.

Like fiberglass mineral wool can be installed in batts. Martin s post focuses on the marketing of owens corning 039 s propink unvented attic insulation system. Thermafiber ultrabatt mineral wool is designed to provide thermafiber ultrabatt mineral wool is designed to provide excellent thermal insulation in residential and light commercial building. Building unvented attic assemblies using fiberglass and mineral wool.

Rockwool multifix is a mineral fiberglass faced stone wool product that can be installed under many single ply membranes. Since it is made from non directional stone fibers the insulation is water repellent microbial growth resistant fire resistant and denser than other insulative materials. An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot. It also provides superior sound control.

Single ply roof systems can provide an easy to install seamless roof assembly. The semi rigid batts are more dense than traditional batts or rolls and are quick and easy to install. The 2018 international residential code irc allows air permeable fiberglass and mineral wool insulation in unvented attics in climate zones 1 2 and 3.