It is very important to insulate the attic, because most of the heat escapes through it. Even if the attic is already insulated, it may still be possible to increase the energy efficiency and strength of the home by sealing the air. Air leaks in the attic can lead to significant heat loss and cause many moisture-related problems. The importance of sealing the air cannot be overemphasized. Read this entire chapter if you are updating your attic for helpful tips and other important information.
Regardless of the type of attic or ceiling in your home, there are a number of things to learn before starting work. Thorough testing of the following features will help you design your upgrade strategy.
Most homes with accessible lofts have an interior skylight, although exterior roofs or wall entrances are not uncommon. The hatch must be large enough for you to load materials. If not, or if there is no access, you can cut a hole in the ceiling in an inconspicuous place, such as a closet. Externally mounted gable-end entrances provide one less opening that will need to be sealed, allowing easy access for firefighters in the event of a fire.
Check the roof area for obstructions and ease of movement. Vertical gaps less than 1 m (39 inches) will prevent you from moving freely. Attics or roofs with no workspace are discussed later in this chapter in Section 5.4, “Cramped Attics, Cathedral Ceilings, and Flat Roofs.”
In addition to checking for structural problems, check the state of the framework roofs, cladding, trim, ceiling and cladding for signs of moisture problems such as leaks, stains, mildew, flaking or rot. Unaddressed moisture problems will reduce the effectiveness of the insulation and can lead to structural damage such as wood rot or chipped rafters. Mold or rot are sure signs of a serious condensation problem. Determine the cause and fix it before adding isolation.
Moisture can come from outside due to failure of the roof or waterproofing. Typical areas of concern include poor highlighting on the thigh, hollow, or chimney, and ice dam leaks. Pay particular attention to water spots on the underside of the sheathing or along the rafters.
Moisture can also come from the home and be carried away to the attic in the form of water vapor when air leaks. Typical problem areas arise around bathroom and kitchen vents that extend through the ceiling, around plumbing and chimneys, and around potted wiring and lighting passages. An indication of an air leak is a discoloration of the insulation, so feel free to look under the existing insulation to find air leaks.
Check the attic during or immediately after a cold snap for condensation accumulation, which manifests itself as frost in cold climates. Some frost build-up should be expected, but if the build-up is particularly severe (10 mm [2 in] or more), ensure that ventilation is present and not blocked by insulation. Checking your attic during or immediately after a rainstorm can help determine if moisture problems are caused by internal or external sources.