The attic is usually the last place to visit during your home inspection. Sometimes just entering the attic is a chore itself and sometimes not even possible. Some home owners will renovate a home and during the process cover up the attic access. This happens more often than you would think and prevents the buyer from knowing the true condition of the attic.
The most common deficiency that I come across in attics is the presence of rodents. Homes that have fiberglass insulation will typically have a varied level of mice infestation in their attic. Rodent proofing your attic will take some time and dedication to the task. Seal all holes and cracks with steel mesh and / or caulking, do not use plastics, rubber or wood that can be chewed. Use traps placed near entry points and empty traps frequently.
Many home owners or contractors will enter an attic to install alarm wiring, cable or to install a ceiling fan. When inspecting the attic there are many times where a trail is visible where individual has walked or crawled along the rafters compacting the insulation. In fiberglass, and most types of insulation, the air trapped between fibers is what gives an insulation factor to product. When insulation is compacted the R value is reduced and you create an area of heat loss in your attic.
Many attics are built using engineered wood trusses. Engineered trusses are designed to support a roof and the normal snow load for your area. If you hang a storage unit from an engineered wood truss you are technically required to have an engineer or designer produce a detail of proposed construction and having drawing stamped. Because the truss is an engineered product it comes under Part 4 of the Ontario Building Code regulations.
Soffit venting is probably the most important factor in preventing ices dams and allowing proper ventilation of your attic. The average roof requires 1 square foot of ventilation for every 300 square feet of roof, low slope roofs require 1 square foot for every 150 square feet of roof. The vents must be 25% on bottom and 25% on peak of roof with the remaining installed where required. It is considered a good construction practice to install upper vents on same side of roof so that air does not just cross over from one vent to the other. Soffit baffles are required to be installed at the eave of the roof to allow air from vented soffit to enter attic. Most subdivision homes will have a soffit vent installed in every third rafter bay.
Many older homes will have vents discharging into attic. Plumbing vents, bathroom exhaust fans and kitchen range exhausts should all ventilate to exterior of house. Newer homes are required to have a insulated wrap installed on exhaust ducts to prevent warm air condensing in attic and forming ice and potential blockage in winter.
Failing to properly ventilate your attic can allow moisture to build up and will eventually cause mould and damage to your sheathing and shingles. Over the years the required insulation for homes has changed. Newer homes will typically have R-50 of insulation installed. If you have an older home your insulation may require upgrading and your ventilation checked to ensure it is adequate.
Contact Barrie Home Inspection Services for more information or details.