Custom cutting of insulation may be required for lessthan-standard width or length cavities or for insulating around window and door framing, stud corners, band joists, and between chimneys and framing. If a faced material is used, and the space, such as at window framing, is narrow, the insulation may be pulled away from the facing in small pieces and stuffed into the narrow space. (See Figure 4.) Small spaces between studs at the corners of buildings and at intersections of partitions and sidewalls should be treated in the same manner before the sheathing is applied. Where a vapor retarder is required, cover the warm-in-winter side of the narrow space with excess vapor retarder facing. Band joists and headers between floors should be air-sealed and insulated. At the band joist, or rim joist, the insulation should be allowed to overlap the sill plate. Small cavities or cracks can be caulked or sealed with cans of spray foam.

Caution

Clearances around fossil-fuel appliances,chimneys and other hot surfaces should meet the requirements of the National Fire Protection Association (NFPA) and International Code Council (ICC) building codes,or the appliance manufacturers'recommendations. Use only unfaced insulation between wood framing and masonry chimneys. Do not place insulation in air spaces surrounding metal chimneys or fireplaces unless they are designed to be in contact with insulation.