The conscientious attic insulation application is much more than blowing in insulation over old insulation. The insulation is added with relative ease and the initial expense is nominal, but overlooking voids in the ceiling and framing, where heated air is forced upward, is a major mistake. Even newer homes are often not built with air sealing in mind. The lack of air sealing can cause a multitude of problems.
Air Sealing is an often overlooked but very important part of a conscientious attic insulation application. Air sealing should be incorporated into every attic insulation job. In every attic there are places where air from the living area escapes into the attic. These places are referred to as ?bypasses.? An air bypass in the attic not only causes the obvious waste in heating and cooling energy, but moisture vapor escapes in the winter months to condense in the attic as it cools.
These bypasses can occur around flue pipes, plumbing vent pipes, electrical wiring holes in top plates, gaps at the top plate on interior partitions as well as external walls, electrical connection boxes and recessed lighting fixtures. Plugging these gaps is tedious work, but necessary as just a covering with insulation will not do the job. Air leaks will cause condensation that will render your new insulation useless. Like a wet tee shirt, your insulation will begin to suck heat out of your living area, rather than keeping the heat inside the living area. Similar to the effect of a wet tee shirt that makes you shiver, the heat escapes into the attic at an even greater rate. All this is caused by attic bypasses and this is only the beginning of the misery caused by air leaks into the attic.
To the left is a photo of an obvious problem, but the top plates (often overlooked) shrink and the junctures at the drywall-to-plates form open gaps. This type of air leak is a major contributor to moisture problems in attics.
The main cause of ice dams on rooftops is the hotspot effect brought on primarily by air leak bypasses in the attic. Ice dams can cause major leaks that can destroy your home. Mold can easily grow on moist construction materials.
Mold growth easily takes hold when liquid moisture is present. Water vapor cannot feed mold unless it condenses into liquid. Attic bypasses must be sealed before any viable insulative work can be done. Air sealing is part of every insulation proposal we offer. It is more laborious to do the job right, but can you afford to have insulation done without air sealing? Do not waste your money on insulation work that will cause more problems than it solves.
Adding Insulation when there is a moisture problem will only cause increased moisture problems. The increased temperature differential causes a greater air movement through bypasses and the colder attic (resulting from the increased insulation) will cause more condensation.