Before ripping out the existing insulation, take a close look at it for hints as to where you may have moisture, mould or air leakage problems. Dark spots can be dust or mould indicating that either air or moisture has penetrated the wall. Insulation is part of a system and if any parts of that system are not in good repair, insulation no matter how state of the art, will not function as it should. Generally, walls have this structure: on the outside, a layer of brick or siding, then an air barrier followed by insulation then a vapour barrier next to the inner wall covering.
A common problem with this structure and also one of the easiest to rectify is air leakage. A great deal of air can flow in and out of small openings such as spaces around doors and window frames as well as out chimneys. The flow of air to the outdoors may not be the only factor increasing heating costs.
Air is in a constant state of motion; warm air flows towards cold air. In winter, the warmth in your home can move through walls, floors and the air to colder spots like the attic, basement and any unheated rooms. Many people think of leaks in terms of openings to the outdoors. However, the movement of heated air into parts of the house that don't need to be at typical room temperatures can be costly. Tight seals on the following problem areas can reduce heat loss: false ceilings, recessed cabinets, doorways into the attic, basement or garage, as well as gaps around electrical outlets, switch boxes and plumbing connections.
Repairing these problems doesn't have to cost a fortune. In most cases all that's needed is come caulking, weather-stripping, plastic or pieces of insulation. For example, look under your sinks and behind your toilets for any gaps between the plumbing and floor or wall opening. You can seal those openings with a strip of insulation, caulking or by spraying in polyurethane foam. If you have an attached garage, the doorway into your home should have weather-stripping along the edges. Attic trap doors can also be sealed with weather-stripping or if the attic is rarely used, consider sealing it completely with a sheet of plastic.
The joint between a porch roof and a side wall can also be a source of heat loss. You can reduce the loss by spraying high-density insulation or polyurethane foam insulation into the joint.
Another benefit of inspecting your home before installing new insulation is that you have an opportunity to look for signs of damage to the moisture barrier. This barrier serves some very important functions. The air inside your home contains water vapour. If this vapour passes into the insulation and condenses, it can cause damage and reduce the insulation's ability to function. Moisture build-up over the years can also lead to mould growth and it may potentially rot the wood. To guard against these problems, ensure your home is adequately ventilated, as with an air exchanger system, and use vapour barriers.
Vapour barriers include treated papers, plastic sheets, and metallic foils that reduce the passage of moisture. Batts and blankets can be purchased with a barrier attached. If new material is being added to insulation already in place, use batts or blankets that do not have an attached vapour barrier. If this type is not available, be sure to remove the vapour barrier facing between layers of insulation to allow any moisture that does get into the insulation to pass through.
A good tip for homeowners who are not sure if the vapour barrier in kitchens or bathrooms is adequate, apply wallpaper with a plastic layer or paint on a coat of oil paint specifically designed for high moisture rooms.
By taking these steps to check for and repair air and moisture leaks and ensure the vapour barrier is functioning properly, you're all set to install your insulation. A warm and cozy home is soon to be yours.