I own two stud finders and neither is giving me consistent results. Need t= o find all of the ceiling joists in my kitchen so I can install 2 light tub= es and 18 can lights. Symmetry is important. Would like to put in 14" dia= meter daylight tubes so joist placement is important. =20 My problem is that the ceiling consists of 1/2 inch drywall under 1/2 inch = plywood. This is throughout the house and is probably why the stud finders= are not consistent. Complicating this is the fact that the joist are all = over the place and not necessarily parallel. I have a few 13" gaps and a f= ew 17" gaps etc. I know this from measuring up in the attic. Further diff= iculty is that I have about 24" of blown in insulation. If I had drywall o= nly (you lucky bastards) I would simply go in the attic and shove an awl do= wn along side each joist, and then run chalk-lines down below. Can't shove= the awl through the plywood! So I'm working down below on a ladder with a= yogurt can attached to my portable drill (wife doesn't like dust) and it t= akes me about 6-7 holes to locate a single edge of a joist. Needs to be re= peated at the other end which takes just as many tries. The next joist can= be measured out 16 inches and still takes about 5 holes due to irregular p= lacement. All together I have about 48 locations to do. Way to slow.
All alternative ideas appreciated. You're welcome to call me an idiot if i= t pleases you. Just help me save some time and effort.
Ivan Vegvary
P.S. I have about 48 findings not because the kitchen is huge, but because= a steel beam runs down the middle of the room below the the ceiling and I = cannot run a chalk line through it.