Can You Insulate a Home with Knob and Tube Wiring?

The Dilemma

Older homes, which tend to be difficult to heat and cool are common in Rhode Island and Massachusetts. With the huge rebates offered by most utility companies to air seal and insulate why aren’t more of these homes energy efficient?

The biggest obstacle to energy savings and increased comfort in older homes is the presence of knob and tube wiring. Even in perfect condition (which is rare) this wiring can get hot which means it must be left exposed and in the open to allow for air circulation. Hence, no contact with insulation. The dilemma is that knob and tube wiring tends to be located in the same space where insulation needs to go, such as attics, basements and exterior walls. The National Electrical Code decreed in 1987 that it would not permit insulation contact with knob and tube wiring systems. Therefore, in order to safely insulate any part of your home the knob and tube wiring in that area must be removed and replaced with modern wiring.

Attic Insulation

When choosing where to begin, start with the attic. Attic insulation is the low hanging fruit. More energy for heating and cooling is lost through the attic than anywhere else in the home. Also, knob and tube wiring found here is relatively easy to access when compared to other areas such as exterior wall cavities. This is why starting with the attic gives the most bang for the buck. Best of all, most utility companies in Rhode Island and Massachusetts through their weatherization programs will pay almost the entire cost for air sealing and insulation. Another incentive available through these programs are zero interest loans up to ten thousand dollars specifically targeted for knob and tube wiring removal.

attic insulation in an older home
Insulation being installed in the attic of an older home.



The next best place to remove old wiring and replace with new is in the basement. Like the attic, wiring here is often accessible and relatively simple to remove and replace. This allows for more air sealing, sill insulation and even floor insulation which can make a huge difference especially over cold basements and crawl space areas.

Wall Insulation

Replacing old wiring inside enclosed exterior wall cavities takes the most time and may require patching and painting of the interior depending on the situation. Likewise installing insulation into enclosed wall cavities which is usually done from the outside, can also be time consuming and may require touch up paint be applied to the siding. However, the benefits of wall insulation are pretty substantial when combined with the attic and basement insulation as this will complete the thermal envelope. On a side note, while this work is being performed it might be a good time to add additional outlets which tend to be few and far between in older homes.

Wall Insulation Installation RI and MA
Insulation being installed in an exterior wall cavity.
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