To make his home air tight, one homeowner used foam insulation from a can, but did not realize that he may have been creating a fire hazard.
As I was walking around the home, my first thought was that they had a home inspector here before. That feeling always puts me on my guard, because there is always the possibility that the homeowner might try to hide a problem, instead of fixing it. One give away was the new caulking and the signs of spray foam insulation. Going inside the home, I saw evidence of a minor electrical fire at a few outlets. These are burn marks on the coverplates. To check the extent of the fire, you open up the plate to look at the wires in the junction box housing the outlet. For a few outlets, this was easy to handle, but I discovered that my homeowner was into DIY projects, and he had not been preparing the home for an inspection.
No home inspector will remove all outlet covers. We simply do not have time. However, in this home, I spent more time trying to pry off covers, with little success. I would have been breaking them. The clues on the exterior which led me to believe that a previous home inspection had taken place were caulking of joints and gaps, with foam insulation sprayed into a few openings where pipes penetrated the wall. Builders do not always seal these gaps (good builders do, but these production builders do not consistently check to see if this has been done). We home inspectors call out these unsealed joints, because during rains, a great deal of water can enter into the wall structure. Particularly on older homes, there is another benefit, sealing joints prevents air flow, which helps energy efficiency. Most newer homes already have products to stop air flow through the walls.
Given the age of the home, I would have thought that these air flow barriers were in place. Maybe there was a failure, and the homeowner facing high summer electric bills had felt air around his electrical sockets. This is more noticeable during winter, so he proceeded to seal the gaps. His next step was to prevent air flow around the outlets. This can be a problem, but it has a simple solution: foam insulating pads which are designed to go behind your outlet covers. These slip in behind the plate, which is then screwed back onto the outlet. In this case the homeowner wanted a really tight seal, so he used these cans of foam insulation. This is a wonderful product for small jobs. The applicator is a small diameter tube that fits into these tiny crevices. The spray will expand, creating a foam barrier. The homeowner had been spraying this product into the gaps where the junction box did not sit flush with the wall surface.
What went wrong? As the foam expanded, the homeowner replaced the coverplates to the outlets. The foam glued itself to the plate, and it expanded into the junction box. Gluing the plate down means that these covers will have to be broken if you need to remove them. Maybe not such a big deal in the scheme of things, but a hassle none the less. The foam which has not caused a bridge between the interior of the junction box to the wall cavity may be a bigger concern. Now we will go into the realm of what ifs. If the wires for the outlets caused an arc, material could heat up to cause a fire. The new AFCI breakers shut down outlets that have these arcs. (Look in your circuit breaker box to see if there are breakers with a test button on them, then read the label on the breaker to see if the breakers is AFCI or an old style GFCI). This spilled over foam insulation becomes an issue with fire safety.
The solution is to cut away any foam that spilled over into the junction box interior. I am presenting this situation to make a bigger point though. On the home inspection the day before I saw this home, I found all of the weepholes had been sealed. My guess was that either the owner had a pest problem or flooding. When I looked at the walls inside the home, I felt that it had been a flooding issue. The repair (sealing weepholes) did nothing to prevent flooding, but it does cause another issue: any water behind your walls cannot escape. Here again we see a do it yourself project miss the mark. When you think about it, making repairs can bring about other problems, and these homeowners were not trying to damage their homes; they were trying to improve them. Before you take on a project, look for simple solutions, but also find out how your home functions to make proper repair choices. Take the time to do the job right.