Your joists are likely running perpendicular to the house.

Use the stud finder that you have and confirm the location by drilling a small hole.

Or use a small rare earth magnet to find the screws/nails in your joists. You can get them at hardware stores.

Here is a link that might be useful: magnet

This post was edited by homebound on Wed, May 29, 13 at 10:37

Take down the light fixture ad use a wire probe to go way from the opening to locate the joists on each side.

Then use the joist finder to clearly locate those two joists.

Measure over 16 inches and look with the the joist finder.

You can then try 24 inches if you do not find the next joist.

Be aware that the joists may not be all that straight on secondary things like a porch and the spacing may not be all that perfect on older work) so drill small (like 1/16 inch) holes in your intended locations to make sure you are on the joist at that exact spot, and even some extra holes to check that you are well centered on the joist if you need good weight bearing.

You can spot the holes with drywall mud or lightweight spackling.
Just put a dab on the hole and wipe with a clean finger, pushing some back into the hole while removing the excess.

It will disappear in the texture easily.

The joists will almost invariably run the short direction of the ceiling.

Make sure the final pilot holes are closer to shank diameter than thread diameter for maximum weight bearing.

It should be pretty hard to turn them in the last few turns (like pliers hard, not finger tight).

If you do not have smooth jawed pliers, use multiple layers of electric tape on the pliers to cover the texture, or even thin pieces of wood.

This post was edited by brickeyee on Wed, May 29, 13 at 11:34

Yes, the joists are likely running across the short way, as you say.

If the ceiling is too rough for the stud finder, try a sheet of thin cardboard underneath it (eg. "cereal box" cardboard).

A couple of rare earth magnets are well worth the investment.

For three reasons, I suspect that the joists run the long way. For one, if the roof is trusses, the ceiling joists are actually the bottom chord of the truss. For another, if conventional rafters, the joist serves as the collar tie to prevent spreading of the lower end of the rafters. And the gable end wall is obviously not constructed to be load bearing, as it should be for short joists. .

Thank you so much for all of the replies! I appreciate your time and advice. I am going to re-attack this project and see if I can't find those joists. I will post back when I do.

Carol

We can pretty conclusively say one thing.

There are some joists up there. :-)

I am exhausted. If there are joists up there, I can't find them.

I have knocked with my knuckles - and then a hammer wrapped in a towel - for hours on end. Can't find them.

I have run my stud finder with a piece of white paper under it over that rough ceiling until I can't do it any more. The light turns off. The light turns green. Run over the same area again and it doesn't do it. Run over it again and it does do it. Then it doesn't. The paper is only 8 1/2 x 11 so frustrating when you get to the edge of the paper. What a hunk of junk.

I have hammered finishing nails through the drywall over and over again. Some resistance and then - slips right in. No joist.

I've been standing on a 8' ladder working on a 12' rough ceiling for hours. I've got pencil, hammer, rag for over the hammer, stud finder, measuring tape, blue painters tape, drill and bit, extension cord, the hooks - all the tools - I'm giving up. This is apparently just not meant to be. Thanks for your time, everyone.

Add running neodymium rare-earth magnets all over the ceiling to the list of things I have tried. The ceiling has a very, very rough surface - it is not popcorn, but a rough hand-troweled plaster - and those darn magnets did not detect one single screw. Not even one. Running anything over that surface, even with the aid of cardboard or paper, is a challenge. Ugh, ugh, ugh. I hate this project. :(

Time for wire probes at the fixture.

Unwind an all metal coat hanger and straighten it out.

Start poking between the electric box and the ceiling at an angle.

Think about what you should feel (make a sketch even) then try all four directions. The box may even be attached directly to the side of a joist.

You can make a wider gap (up to 1/8 inch and not have to fill it in) if you need to.

The light canopy should cover the access when you are done (the box behind there is likely only a 4 inch octagon box).

There should be nothing electrically live outside the box unless you have old knob & tube wiring the insulation has fallen off of.

The biggest danger is falling off the ladder, not electric shock.

This post was edited by brickeyee on Sat, Jun 1, 13 at 10:52

Brickeyee, you are so kind to hang with me. I really appreciate it.

I ordered a better quality studsensor today from eBay (Zircon e50). I will have it within a week. It is supposed to sense through thicker walls and with that very rough ceiling surface, I think that is part of the problem with the one I have. As I am running over it, it is like surfing over upside-down waves in the ocean: it moves up and down. I started to notice that the light would come on, on my cheap studsensor, every time I ran over a thicker part of the plaster. If I can't get it with the better studsensor, I will remove the light fixture and use the wire coat hanger technique. I hate to let a project beat me! Thank you so much for sticking with me.

Carol

PS. I am reluctant to take down that light fixture because I remember how hard it was to put up there by myself. :(

I applaud your tenacity.

Here's another idea. Test with a finishing nail around the ceiling perimeter, right through that bead of caulk. Later you can patch it. Go every inch until you find the first joist, then 16" or 24" from that one, etc. It will at least give you something to do until the sensor arrives.

One other thing. Any handy neighbors around? You just might need a fresh pair of eyes on this one. Good luck.

By the way, have you considered wall mount plant hooks or a rod?

Some of them might fit nicely above the windows, then use in combination with chains to drop the plants to various heights.

Just a thought.