The Inspector Newsletter
August 2014: Attics and Roofs
Maintenance Matters

Maintenance Matters

Does Your Attic Have Enough Insulation?

One thing inspectors check for while inspecting the attic is whether there’s enough insulation. The purpose of insulation is to act as a barrier between the attic and the house and help with climate control. Thus, in the summertime, insulation keeps the heat in the attic and out of the house; in the wintertime, it keeps the cold air in the attic and out of the house. In addition, by preventing heat loss in the winter, insulation works with ventilation to prevent ice damming on the roof in parts of Canada where that condition is a problem.

Ideally, an attic should have between 18 and 22 inches of insulation to properly protect the climate of the home and roof. As energy prices increase, it’s important to be sure that your home has the proper amount of insulation.

If your attic is lacking insulation, it’s easy enough to roll additional bats of insulation up there, or, if you have an older house with a small attic access opening to either blow insulation into the attic yourself or have this service done for you. The cost to have additional insulation blown into an attic usually runs a few hundred dollars.

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Did You Know?

What You Need to Know About Knob and Tube Wiring

Knob and tube wiring (KNT) was the first wiring system to be introduced to residential homes and commercial buildings. The systems date as far back as the late 1800s. The National Electrical Code (NEC) wrote specifications as to how the systems were to be installed. KNT refers to porcelain insulators that were used to support the wire (knob) as it was strung along the joists and runs for the wiring itself. The tubes were used to protect and insulate the wire as it passed through wall studs, floor joists, etc.

The knobs suspend the wire to keep it from contacting the wood, and the tubes protect and insulate the wire as it passes through the floor joists or wall studs. Knob and tube systems were replaced in the late 1940s with the first stages of cloth-wrapped cabling (first type of Romex) that combined the hot and neutral wire wrapped together in a bundle. The wires were run through a rubber insulator then held together by the cloth wrapping.

By the early 1960s, that type of wiring was replaced with today’s more common type of cabling that is all plastic-wrapped (typical Romex wiring).

KNT wiring is now old and obsolete, and in many cases it’s a fire hazard — not by design of the system, but because of age: the rubber insulator that the wire was originally wrapped in can be old and brittle.

Many insurance companies now will not insure a home or building that contains KNT wiring, and there are many homes and buildings out there that still contain active KNT systems. Typically, if a home contains KNT, it’s visible in the attic. Wiring can be tested with the right equipment to determine whether the system is still active. Just because that wiring may be found inactive in an attic doesn’t mean the wiring that may still exist in the walls is.

When inspectors find a home with KNT wiring, active or not, it is recommended to have the entire electrical system fully inspected by a qualified licensed electrician to completely disable the system or possibly rewire the entire home. It is recommended to check with your insurance company whether or not they will insure the home.

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