Some of the best tips for floor joist insulation not only cover the insulating materials that are best to use, they also cover those materials that are best left alone. Wooden floor joists expand and contract with changes in weather, therefore, the floor joist insulation must also be able to expand and contract. Another tip concerning floor joist insulation is to avoid using fiberglass batts whenever possible. Hard board-type foam or an expandable spray-type foam are the best materials to use.
Fiberglass insulation is commonly stuffed into cracks and crevices around a foundation in an attempt to insulate a structure's floor joists. Common fiberglass insulation does not work well for this type of insulating. Air freely flows through fiberglass of insulation, rendering the insulating properties close to zero in most flooring applications. The tip here is to use foam-type insulation in either a board-type or an aerosol can. Another tip when using a spray-on floor joist insulation is to wear protective clothing to eliminate cleanup difficulties when finished. A disposable suit, complete with hat, gloves and eye protection, can save a lot of aggravation later if the foam has to be removed from skin and clothing.
Other tips to make floor joist insulation more enjoyable and functional is to remove any fiberglass batting-type insulation from the floor joists prior to applying the foam. This tip actually aids in another step that involves drying the wood before insulating the joists. The floor joists and especially the rim joist can become wet with evaporating moisture and must be dried. Failure to dry the lumber could result in poor insulation adhesion, premature wood rot and even mold issues. It is critical to allow the wood to dry before installing or applying floor joist insulation.
Tips for floor joist insulation also include spraying the expanding foam in one quick and continuous movement once it has begun flowing. Failure to spray the foam material for three minutes or more will cause the foam to harden inside the applicator gun as well as the hoses connecting the applicator gun and the foam supply tanks. Tips for an easy cleanup with the applicator gun involve using petroleum jelly on the exterior of the gun. In placing the petroleum jelly on the outside of the applicator gun's nozzle and trigger assembly, the spray foam floor joist insulation will not be able to stick to the plastic. This makes it much easier to clean up and remove when finished.