Question about a weird seam I had to fix in a 1970s house in Portland

I was working on a job last month in this old ranch house in Portland, the kind with the original shag carpet still in the bedrooms. The homeowner wanted to keep the living room carpet but replace the hallway. The problem was the seam between the old and new. The old carpet was so worn and the backing was brittle, it just kept fraying when I tried to seam it the normal way. My boss, who's been doing this for 40 years, showed up and told me to grab a can of spray adhesive, the 3M Super 77 kind. He had me spray a thin line on the old backing right at the cut, let it get tacky, and then press the new carpet into it before putting the seam tape down. It acted like a primer and held all those loose fibers in place so the hot melt tape could actually bond. I never would have thought of that. Has anyone else had to use a trick like that on really old, shot carpet?

2 comments

2 Comments

lisayoung17h ago

That method seems like a short term fix to me. Spray adhesive can get gummy and fail over time, especially with foot traffic. It might hold for now but could cause the seam to split again later. I'd rather cut out a bit more of the old carpet to find a section with backing that's still solid. It takes more work but the seam tape bonds properly then.

juliag1922h ago

That Super 77 trick is a classic old-timer move. I see it all the time with old materials, like using hairspray to stop a nylon run or duct tape to temporarily fix a vinyl car seat tear. It's never the textbook fix, but it's the real world one that gets the job done when the proper stuff just won't stick.

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