OT: wall weirdness

Ooooo! You said "bathroom".... Ooooo!
Remember that a stud-finder is also an effective "pipe finder". "OOPS! Honey! Would you run out to the street and turn off the water?"
Bathroom studs are often oddly-placed to make room for vent stacks and plumbing trees. You better _carefully_ make some viewing holes, then patch them later.
LLoyd

You could have two weird studs where some different sets of walls come together - but given the bathroom aspect, I'm betting one of those objects is the plumbing stack, or another pipe/wire. My secret weapon for studs, which works a bit less vaguely than the studfinder, is a very strong, small magnet (rare earth type).
I sweep around the wall and circle all the spots the magnet sticks to - this generally reveals a pattern of nails or screws which are hopefully going into studs.
If you have plaster and wooden lath, the studs will be dotted with a LOT of nails. If you have plaster on steel mesh lath, this won't work at all, I expect.
Opening up an inspection hole might be a good idea. Patching drywall is a lot easier than patching plumbing or wire.

There wasn't a lot of new construction using plaster in 1979. Maybe you're just looking at a patched area of drywall.
Bill Schwab wrote:

More than likely you have some combination of off center studs to support the 4" vent stack going up the wall, a 5-1/2" cavity for the stack, a cutout for a vanity mirror, and a hack job remodeling. It's unlikely that you have plaster, much more likely to have a huge gob of drywall mud covering various sins.
Head off to the basement, see where the pipes (large and small) are going in relation to the wall. It's common to be able to use a flashlight and inspection mirror in the basement to get a handle on what's there. Plan on cutting an access hole if you are real fussy, otherwise just drill 3/4" and verify you hit a stud.
Bill Schwab wrote:

Scary, taking a 3/4" drill to a wall of unknown contents. I recommend you drill a 1/4" or less hole very carefully, but go no deeper than about 3/4" into the wall. Poke in a stiff wire and feel around. Recently in my kitchen I found a bit of the drain pipe where one bit of it had to clear the structure below, so if you were to attempt brute force drilling, you'd go right through it. The bottom of the sheet rock where it met the floor was notched out to clear the pipe, and it was right up against the sheet rock since some pipes had to go behind it. I was all ready to drill through it when something didn't feel right. That would have really sucked, even more if the wall and cabinets were in. There is a copper vent pipe behind the wall in my half bath with a 1/8" hole in it, or at least a heck of a drill start. Wasn't paying enough attention to the fact it felt different!
| Head off to the basement, see where the pipes (large and small) are | going in relation to the wall. It's common to be able to use a | flashlight and inspection mirror in the basement to get a handle on | what's there. Plan on cutting an access hole if you are real fussy, | otherwise just drill 3/4" and verify you hit a stud.

Roy,
Thanks, I'll do some more searching.
Maybe the two different surfaces are somebody's idea of decorative expression, but it feels and sounds like a different wall covering. That said, you could easily be correct.
There is a concrete slab down there :( I might be able to attack it from above, but it's not the easiest crawl space in the world (I have that from guys who do that kind of thing for a living), and it's all the way on the other end from the access. One easy thing to try would be to locate the vents relative to a skylight.
Ultimately, I will have to resort to a test hole; the more accurate I can be on the first shot, the better.
Bill

I like the one inch long blade in the sawsall that someone in this group suggested. Karl

If you are describing a crawl space with a slab I have a suggestion that a friend used. Buy one of those crawlers that garage mechanics use to get under a car. Leave it in the crawl space. My friend could scoot around that crawl space faster than you could walk in a full basement. You use the floor joists to pull yourself along.
You should be able to drill a small hole through the floor tight to the wall and insert a wire to locate that section of wall that you want to explore. Drill a larger hole from below and poke around with a coat hanger or cut a slot so you can see what is in the wall cavity.
Nice place for one of those LED headlamps.

Around here, no one cements over the crawl space in spite of radon gas concerns. Newer houses have plastic, older are just dirt covered with random trash, beer cans, scrap 2x4's and sawdust. Ugh.
Find a 12" long x 1/8" drill, go down behind the baseboard, leave it hanging out below.
Yep, $10.

3/4" DEEP!!
I got a call from a friend, he had a "handyman" come over on Saturday to sheetrock a bedroom. Spent Sunday finding a repairing the screw through the copper pipe to the bath, spend Monday night finding the sheetrock screw through the NM cable to a switch. BTDT
carl mciver wrote:

Ouch!
The reason that happened is no screw protection plates over wires and pipes. Some places have different local laws on this - no Federal mandate.
When the law is required, - oh the price it is to put them in... :-)
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
RoyJ wrote:

This is an easy one- assuming you have a back on the cabinet you want to hang. Mark out round the edges of the new cabinet, locate the horizontal pane you want to screw it on. (this is variable, dont worry about it too much - approx will do).
Now, with a panel saw, do a shallow cut ACROSS the wall, you will find the studs. Rip the plaster off enuff to confirm it is a stud, not a spare bit of wood, or packing. ( a keyhole saw is ideal for this, 2 bucks at the hardware.) I say hand panel saw, so if theres anything nasty in there (ie pipe, power cables) you wont do too much damage.
Voila - you have located your mounting points. Transfer these measuremnts to your cabinet., using the cabinet perimeter guidelines you have already marked out, with a piece of scrap 2 by 1, and off you go,
There is nothing subtle about this sort of stuff - house building is NOT an exact science - thats why they invented plasterboard and paint to cover up the work behind it...most builders are more than happy with half inch tolerances.
if you want to be REALLY fussy and cover your cut line, go buy a bag of cornice cement, mix up, and trowel on. Use the biggest trowel you have to smooth off well and do it FAST. Dont bother sanding, unless you want the house full of plaster dust. Better to get it right while its wet. And dont expect the wall to be true, or the corners straight - they wont be.
Hope this helps,
Andrew VK3BFA.
re your sparky - sad, but true - its like very other trade - some take pride in their work, othere just do it to pay the bills.

Cheapest and simplest stud finder is a small cylindrical rare earth magnet
they will stick to nails in the studs through the drywall
Non invasive cheap and almost idiot proof
Andrew VK3BFA wrote:

I like using the wires meant for holding insulation batts for just this purpose.
Shawn