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Does Spray Foam Insulation Affect Electrical (or Other) Work in the Attic?

May 20, 2016

While there may be debate between individual contractors about spraying foam insulation over electrical wires, industry guidelines state that spray foam insulation can be applied directly over electrical wiring. The fact is, when wiring is properly sized and housed, there should not be any temperature issues as a direct result of the spray foam. As for applying spray foam to seal up recessed lighting fixtures (or other fixtures), this may necessitate some air circulation to ensure cooling. There are a number of construction options that will accommodate this. In terms of ensuring accessibility to electrical outlets, junction boxes, and lighting fixtures, it's a good idea to plan it out ahead of time, well before the spray foam insulation is even applied. For a good insulation contractor, this is academic, because it becomes part of the overall project, and planned accordingly. In fact, in some cases, empty electrical conduits can be installed (for future use) and easily covered with spray foam. In this way, an electrician can use the hidden conduits to route wiring without having to break open the already installed spray foam. Another aspect of spray foam insulation, with respect to electrical wiring, is its capacity to block moisture - a definite advantage with electricity. As it is, industry groups have conducted several decades of extensive testing, finding that spray foam insulation does not affect electrical wiring when safely applied and installed. Importantly, old "knob and tube" wiring cannot be covered over with spray foam insulation. Here, a professional insulation contractor will recommend the removal and re-installation, with upgraded, building-code-rated wiring. Spray foam insulation is not corrosive to metal. When spraying on or around existing wiring, the gauge/voltage of the wiring should be taken into consideration. There are, however, concerns with wiring that is low-voltage. For the most part, experienced contractors will avoid spraying this type of wiring, and in any situation, will choose to be safe rather than sorry. Most attic insulation products are installed over and around electrical wiring, and spray foam is no exception. The key, of course, is a professional installation, so that potential overheating of electrical wires is totally prevented. This is definitely not the appropriate time for a do-it-yourself installation. At Great Northern Insulation, specializing in spray foam is about having a team of experts with years of product experience and installation expertise. Install teams always work according to recognized industry standards, and follow all applicable building codes. It means that electrical wiring, HVAC ductwork, and interior plumbing is handled with care. As well, GNI installers don't take shortcuts, and work to the manufacturer specifications. This expert approach to installation provides the homeowner with the assurance that everything is safe. GNI installation teams are licensed and certified with spray foam products. They prepare the job site the right way; they use appropriate protective gear and safety equipment; and they make certain that residents and occupants are safe during the installation process. In the attic, roof, basement, or garage, spray foam can deliver excellent results, but it's an insulation product that must be expertly installed and professionally managed.

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HomeStars has ranked Great Northern Insulation as a company that goes above and beyond in every aspect of business for the year of 2022.


GNI is the Authorized & Trusted Insulation and Air Sealing Installer for Lowe’s

Trusted for Over 40 Years

Over 40 Years in Business

At GNI, we service your project with the most experienced staff in the industry. Ongoing professional development is an obsession at GNI and we will not compromise at any level to bring to our customers the very best Installers, Sales Representatives, Customer Care Personnel, Field Superintendents, Estimating and Technical Support to your project.

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Great Northern Insulation is recognized as Canada's largest full-service insulation contractor. GNI is 100% Canadian owned, proudly serving Ontario customers since 1980.

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January, 2021 regulatory phaseout of hydrofluorocarbons (HFCs) with the introduction of WALLTITE CM01. Using hydrofluorolefins (HFOs) with lower global warming potential (GWP) compared to HFCs, WALLTITE CM01 is the next generation of spray foam insulation.



Heatlok® Soya HFOTM leverages Honeywell’s latest Solstice® Liquid Blowing Agent technology. This new hydrofluoroolefin (HFO) blowing agent is the most environmentally conscious blowing agent produced to date, with a zero ozone depletion potential (ODP) and a global warming potential (GWP) of 1, which is more than two orders of magnitude (99.9%) lower than HFCs used in this industry.


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3MTM energy-saving products are designed to keep warm air in, and cold air out, while keeping energy bills down. Products optimize energy efficiency in buildings and homes; improve indoor environment for occupants; and effect the reduction of seasonal energy costs. 3M products are authorized for LEED credits (Leadership in Energy/Environmental Design).

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Mike Holmes and his son Mike Jr. (MJ) convert MJ’s bachelor bungalow into a two-storey home for MJ and his girlfriend Lisa. Choosing the newest materials and build techniques, the father and son team follow Mike’s famous motto – “Make it right.” The show can be watched on HGTV and DIY Network.


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CLIMATIZER PLUS cellulose insulation is manufactured from a minimum of 85% locally-sourced post-consumer recycled newsprint. Non-toxic additives are applied to the uniquely fiberized paper generating a building material with superior thermal and acoustic properties, as well as exceptional resistance to fire, moisture, mould and pests.

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