Insulation Inspections

Insulation Inspections by the Angus Home Inspector

Insulation Defects by Angus Home InspectorThe Angus Home Inspector performs an inspection on the insulation and the 6-mm poly vapor barrier that separates the outside conditions from the inside. Proper installation of the insulation and vapor barrier in a home will create lower heating bills as well as the ability to keep its occupants comfortable.  The builder will  install fiberglass R-20 batt insulation on exterior walls, and minimum 12-inches of blown-in fiber insulation to achieve R-40 in your attic. Higher insulation value in the attic serves two purposes.  First, it prevents heat loss in the colder months as heat rises within the home that can be lost with lower insulation in the attic. Second, it prevents the heat from the sun being absorbed during the warmer months and this will help prevent the second floor from becoming too warm.

Requirements for attic ventilation were equally loose in section 9.19, requiring a minimum of “1 square foot of unobstructed vent area for every 300 square feet of insulated ceiling area.” This requirement has remained unchanged since the 1960s.

Insulation Requirements Amount of insulation required in attic spaces is RSI 7.0, R-40. (equivalent depth of loose fibreglass insulation is about 14 inches) Installation
“where soffit venting is used, measures shall be taken:”

  1. “to prevent loose fill insulation from blocking the soffit vents and to maintain an open path for circulation of air from the vents into the attic or roof space”
  2. “to minimize the air flow into the insulation near the soffit vents to maintain the thermal performance” (see


Angus Home Inspector and Asbestos InsulationAsbestos Contamination – Prior to its closing in 1990, much of the world’s supply of vermiculite, according to the US Environmental Protection Agency (EPA), came from a mine near Libby, Montana owned by W.R. Grace. This mine had naturally occurring deposits of asbestos that contaminated the vermiculite. It is thought that most of their production contained at least trace amounts of asbestos fibre. Although vermiculite processed with a binder (such as concrete and plaster mixes, sprayed, fireproofing, etc.) is unlikely to ever release significant airborne asbestos, loose fill products do pose a risk, causing substantial asbestos exposure when disturbed. This asbestos-contaminated insulation from this mine was installed in many Canadian buildings, most of which were homes, but also in commercial, institutional and industrial buildings. Use in Canadian residential construction heightened with the CHIP Program between 1977 and 1984, the same program under which most Urea Formaldehyde Foam Insulation (UFFI) was installed. Vermiculite Insulation Sources – Vermiculite is used in a variety of products for both commercial and consumer use, including building materials. Processed raw ore was shipped to many plants in Canada for exfoliation or expanding where it was heated to about 1000°C causing it to expand into a lightweight granular looking material.


Mould on Sheathing - Angus Home InspectionsBuilding science experts have long been using the “house as a system” approach to diagnose the cause and origin of building defects.

For example, ice dams. These are often caused by warm air seeping into the attic which causes the snow and ice on the roof to melt. The water drains to the edge of the roof (which is colder than the rest of the roof because it is an overhang and not warmed by the attic), freezes and creates an ice dam. As this process is repeated daily, the ice dam grows larger. Eventually water is forced under a shingle where it can seep into the house.

Understanding how the house behaves as a system and the various causes and effects is necessary todiagnose most building related problems. But how about that attic mould? How did it get there?

Mould requires chronic moisture to form and to thrive, so source(s) of moisture must be present. Possibly the moisture came from outdoors. The roof is newer and a quick check of the roof shows no obvious damage or leaks.

Possibly the moisture came from indoors. During the heating season, the interior of the house frequently has high moisture levels, especially bathrooms and kitchens. A quick check shows that all bathroom fans, kitchen vents, etc. are properly ducted completely outdoors and not into the attic. The amount of insulation looks good and the attic is well ventilated.