Stabilize a Shaky Floor

LESLIE: Boing, boing, boing, boing, boing; that is what’s going on to Stephanie’s floor in Utah. Are you bouncing everywhere; are the kids jumping up and down? What’s going on?

STEPHANIE: (chuckling) Yes, whenever the dogs run through the house the kitchen island goes shaking because the floor is so bouncy. (Leslie chuckles)

TOM: Hey Stephanie, how old is your house?

STEPHANIE: My house was built in 1989.

TOM: OK. And the kinds of floor joists that you have, is it a solid floor joist; is a truss joist; is it one – do they look like plywood I-beams?

STEPHANIE: They’re I-beams and they’re 24 on center.

TOM: How did I know that? (chuckles) I knew exactly what was happening when you said the floor was bouncing. Yeah, when you use those plywood beams, what happens is they have more flex than a standard floor joist and so they do bounce a lot. They’re not weak in terms of a structural issue but, man, the China sure rattles around when that happens. And I’m not so sure there’s an easy way to fix this. There’s a couple of things I’ve seen done.

They’ve put bridging on that attaches to the bottom of the floor joist all the way across. I’ve always also seen folks construct what kind of looks like a girder in the middle of that span so that you’re shortening the length of the floor joist from, you know, whatever they are to half of what that is. The girder wouldn’t necessarily have to have any sort of footing because it’s really just there to take the flex out as they bounce. But the last thing I would check is to make sure that none of those beams have been cut improperly because one common error that we see, especially with HVAC contractors – heating and air conditioning contractors – is they’ll cut out part of the web, either the bottom web or the top web, when they’re running duct work. But assuming that that’s not happened, that flex is, unfortunately, fairly normal for that type of floor system.

STEPHANIE: OK, wonderful. I’ll take a look into those options.

TOM: Alright, Stephanie. Thanks so much for calling us at 888-MONEY-PIT.