Mitered some corners on a tricky stair job and they came out gapped

I was installing a tight pattern carpet on a curved staircase in St. Louis last week and tried mitering the nosings like I saw in a YouTube tutorial... but the seams kept pulling apart overnight. Anyone else had trouble with mitered corners on stairs with heavy traffic patterns?

3 comments

3 Comments

the_harper1mo ago

St Louis humidity is brutal for mitered stairs, nobody talks about that enough. The carpet backing actually expands and contracts way more than people realize when the seasons change, especially on curved steps where the substrate has more movement. You might need to switch to a different adhesive that stays flexible instead of that hard setting stuff they sell at the big box stores. Also check if your tack strip spacing is too far apart on the curved sections, that can create extra pull on the miters overnight. Try using a heat gun to relax the backing before you tuck it in tight, that helps the fibers settle without springing back.

knight.felix1mo ago

Yeah that's the thing about humidity nobody really connects the dots on until it's too late. @the_harper you're right about that adhesive thing, I've seen guys use that cheap stuff from Home Depot and then wonder why their work pops loose in August. It's like the whole house breathes with the seasons and people just ignore it. Carpet backing's got memory too, it'll fight back if you don't warm it up first. Heat gun trick works but you gotta be careful not to melt the fibers, just get it pliable enough to behave. Honestly the same principle applies to a lot of flooring jobs, wood or vinyl or carpet, everything moves and you gotta work with it not against it.

keith9001mo ago

@knight.felix nailed it about the heat gun risk though, you gotta be real careful not to melt the nylon fibers.