Floor Joists MiA?

[L5wolvesf]

So I had a leak behind the shower in our house. Got the leak fixed and need to repair the soaked particle board subfloor. Generally not a big deal except I can’t find floor joists. Since this is the only bathroom ripping up a huge chunk can only be done as long as I get it closed up quickly. I pulled out some linoleum (the paper-like backing didn’t come up) and used a stud finder to try to find a joist. My normally trusty Zircon stud finder found nada, battery is good and it will find wall studs. So Plan B, drilled a 2 inch hole off to the side and take a look with a flashlight and mirror. I found a joist that runs along the open side of the shower, about 16 inches from the hole – great. So I check 180 from there stick the inspection mirror in and then a grabber tool and find . . . nada. From what I know the joists should be either 16 or 24 inches on center.

FWIW, the house is a converted 1970s mobile. All that is left of the mobile is whatever is under the floors plus the bathroom and kitchen. The 16 or 24 inches on center should apply in this case from what I’ve read. Also, I had to do a floor repair in another part of the house about 10 years ago and I found the floor joists easily.

So I’m facing 32 or more inches on center floor joists? The floor has never been noisy or soft. Is that even a thing? Am I missing something? A better tool to find the joists?

Thank you in advance

 

[PugetDude]

I use an 8D finish nail... pound it in the most likely locations. (16-20-24 OC) When you find a stud/joist, angle it from side to side to find center.
Since you've pulled up the linoleum, the holes shouldn't be a problem.
.

I've also used an inspection camera- my little Ryobi wlll fit through a ~5/8 diameter hole.

Good luck.

 

[Barnabas]

Maybe the joists run the other direction in that room?

 

[driftpin]

If it's a mobile home, don't you have great access underneath, from some access door?

 

[Marctrees]

Stud finders are for those that do not have sufficient construction knowledge...

Nor are able to understand and do do proper minimal discrete probing w properly shaped coat hanger etc...for the specific instance, ..

sometimes w little loop end, ..

Othertimes cut w Dykes held in the CORRECT orientation to make a "drill bit" for easy piercing of sheetrock paper held in hand, ...

even hardwood floor layer chucked in drill..

or other minimally invasive tools.

it's all knowledge and technique.

Marc

 

[tonyciambrone]

I use neodynium magnets to find drywall screws on studs. I assume a decent sized magnet would find whatever the subfloor anchors are and go from there.

 

[RVDan]

Mobile homes aren't built to any reasonable code. Don't count on floor joists being anywhere near where you need them to be.

 

[Lynden]

Try one of these...

https://www.homedepot.com/p/C-H-Han...gclsrc=aw.ds&dclid=CLeCo4LojN4CFR4ErQYduSQCJQ

 

[3rdgendslmech]

I've redone sheet rock in few different houses, 2 were built in the 80s and here's what I can tell you that I saw.
If it's an interior wall that's not load bearing and 8' or less, there could only be 1 stud in the middle lol. I've seen corners that had no support for the drywall. I've seen load bearing walls that had 16, 20 and 24 inch spacing in the same wall.

 

[L5wolvesf]

Thanks guys, it looks like I found it. It’s about 36 inches on center. I’m sort of surprised the floor has never made noise or flexed.

On the metal finding recommendations – good idea and I had an eye out for nail or screw heads. It looks like the subfloor was glued down no nails or screws.

Mobile homes aren't built to any reasonable code. Don't count on floor joists being anywhere near where you need them to be.

This comment got me out of thinking this was built to some code.

minimal discrete probing w properly shaped coat hanger etc...for the specific instance

Mentioning a hangar helped but I haven’t seen a metal one here in a long time. That’s why I first used a flexi-grabber, but it was just too short. The hanger did remind me of some old 1/4in copper tubing I have which was long enough to reach the floor joist.

If it's a mobile home, don't you have great access underneath, from some access door?

Yes there is access, but not a door just some blocks that can be moved. It’s a project to correct but down the line some.

Maybe the joists run the other direction in that room?

I had considered that at one point but it didn’t make sense to me.

I've also used an inspection camera- my little Ryobi wlll fit through a ~5/8 diameter hole.

That has been on my wish list, I may need to move it up the list some.

 

[Falcon67]

Mobile homes aren't built to any reasonable code. Don't count on floor joists being anywhere near where you need them to be.

They are around here because what used to be cheap double wide at $24K now runs 80~100K. Sheetrock walls, wind ratings, etc, etc. If it's an old mobile, then maybe true. Not so much "joists" as "stringers" and most of the floor supported by steel wings coming off the main beams. Particle board floors used to be the thing for those and not anything that could put up with standing water for more than a few minutes. Been there lived that.