Finding Joists Through Hardwood - Stud Sensor?

[tev9999]

I'm recarpeting the living room soon and want to eliminate all of the squeaks in the floor. I've got 5/8 or 3/4 hardwood over 1X6's diagonal to the joists. The hardwood is in pretty bad shape and I never plan on refinishing it, so my plan is to just drive screws through it to the joists.

My basement is finished with 12 X 12 interlocking acoustic tiles, stapled to furring strips - not a fun thing to remove to get a look at the joist locations.

Is there a stud sensor out there that could find the joists from above? The zircon website says up to 1.5" deep, but I'm close if not over that.

[Tom]

I suspect they are referring to 1.5" of drywall, not 1.5" of solid wood. I would think that all you have to do, is find one stud from below, drill a hole up through the floor next to it, and then just measure from that hole, the distance the joists are apart to find the rest. Find them at the walls and use a chalk line to mark them across the floor. Tom G.

[tev9999]

Their website does refer to solid wood.

I discovered in the kitchen that my joists are not exactly on 16" centers - some 15, some 17. I missed many times with the measurement method in the kitchen.

[Heathcliff]

I would think you would have a decent chance with the stud sensor, especially since there should be a nail through each hardwood strip into each joist. When I have used stud sensors they seem to also detect pipes and such in the wall. Of course there is always the knuckle-rap method. You will probably want to drill pilot holes for your screws anyway, so that would be an opportunity to confirm you're in the right place. --H

[barry]

Just fire away, possibly with drill before driver, for each screw, locating where you guesstimate there's framing below. If you miss, try again nearby. Any problem with a few "spare" holes in your new hardwood subfloor? Didn't think so.

Of course, there are simple strategies to reduce misses, if it matters. E.g. locating approximate joist center at each extreme of floor area, than marking line between pair of points for rest of holes to joist.

I assume you mean "real" screws, not crappy brittle drywall screws. Like, deck screws.

HTH, J

[John McGaw]

I tried scanning for floor joists through hardwood and subfloor just one time to make an opening for a new return air duct. To my surprise it worked perfectly. The detector is a Zircon "VIDEOSCANNER 5.5" and it has a regular scan and a "deep" scan and at this late date I can't remember which mode I used. But even then I did drill a couple of tiny test holes to reassure myself before whacking a great hole in the floor.

Measuring for some assumed spacing with floor joists is probably not as reliable as when locating studs since doubling of joists to support walls and heavy loads is pretty common and when a wall upstairs falls between normal spans you will usually find an extra joist thrown in to support it.

[tev9999]

Thanks for the info. I need a new sensor anyway - my old one is very tempermental. I'll make sure I get one of the deep scan models.

[Frank K.]

Make sure you use screws that DO NOT have threads that go to the head. You need to have plain shank so they draw down the flooring and not keep it suspended.

Frank