Insulation and Knob & Tube Wiring
This time of year Mother Nature reminds us how powerful she can be. We receive numerous inquiries from prospective customers wanting to know if we can inject spray foam insulation into existing walls. While we can most certainly do this if the wall cavity is empty, the first thing our Salespeople and Certified Applicators look for is Knob & Tube wiring within the structure. If there is any, we always recommend bringing in a certified electrician.
While we are definitely experts in spray foam insulation, we would never undertake wiring a home. We here at Iowa Spray Foam always refer to a professional electrician for their services.
Why is insulation and Knob & Tube a bad combination?
Knob & Tube wiring needs space to keep it cool. When spray foam insulation (or any insulation for that matter) is installed around it, the insulation restricts the wiring from dissipating the heat in the wire when electricity is energizing the circuit. If the heat is not properly dissipated, the wiring could overheat and potentially cause a fire. This is part of the reason that the tubes come into play: they prevent the wire from touching the framing or other materials, preventing fires.
You must also keep in mind that some of this wiring could be as old as 80 years old. We have witnessed some homes where the protective insulation wrap around the wiring has fallen off or has even been chewed off by rodents. So while most people don’t really want to spend money on upgrading their homes, it is really a good idea.
Don’t believe us? See what This Old House has to say about Knob & Tube: “Faced with drafty houses and high heating bills, homeowners often add thermal insulation to their attics and walls. Insulation on top of knob and tube wiring is a major fire hazard.” They go on later to state, “In 1987, the National Electric Code prohibited the placement of insulation in contact with this type wiring.”
These concerns come into play not only inside a wall cavity, but also in attics, crawl spaces, or even basements when installing spray foam insulation. This is just another reason to make sure you are looking for professionally trained and certified spray foam insulation contractors for your projects. Call us at Iowa Spray foam for your next home project.