9.25.2.4.Installation of Loose-Fill Insulation

(1) Except as provided in Sentences (2) to (6), loose-fill insulation shall be used on horizontal surfaces only. (2) Where loose-fill insulation is installed in an unconfined sloped space, such as an attic space over a sloped ceiling, the supporting slope shall not be more than (a) 4.5 in 12 for mineral fibre or cellulose fibre insulation, and (b) 2.5 in 12 for other types of insulation. (3) Loose-fill insulation is permitted to be used in wood-frame walls of existing buildings. (See Note A-9.25.2.4.(3)) (4) Where blown-in insulation is installed in above-ground or below-ground wood-frame walls of new buildings, (a) the density of the installed insulation shall be sufficient to preclude settlement, (b) the insulation shall be installed behind a membrane that will permit visual inspection prior to installation of the interior finish, (c) the insulation shall be installed in a manner that will not interfere with the installation of the interior finish, and (d) no water shall be added to the insulation, unless it can be shown that the added water will not adversely affect other materials in the assembly. (5) Water repellent loose-fill insulation is permitted to be used between the outer and inner wythes of masonry cavity walls. (See Note A-9.25.2.4.(5)) (6) Where soffit venting is used, measures shall be taken (a) to prevent loose-fill insulation from blocking the soffit vents and to maintain an open path for circulation of air from the vents into the attic or roof space, and (b) to minimize airflow into the insulation near the soffit vents to maintain the thermal performance of the material. (See Article 9.19.1.3.)