Does anyone have a good method for fishing across a plaster ceiling. I only have to go about 12' but the joists are running across at 10" centers and I want to minimize the damage to the ceiling. I was thinking a 4-3/8" hole saw at each joist and drilling through the joist w/ an auger bit but it seems like alot of damage to the ceiling.
Thanks for any suggestions.

I've heard that some would use a D'Versibit for this, making one opening and using it to drill maybe two or three joists. I have never been very sucessful with them. Besides, I always like to see what I'm drilling into. Never know what is running with the joists.

-Hal

CVelectric,

I agree with hbiss, but before I drill through rafters with one of those long bits, I would make a small hole with a long thin screwdriver along side of the rafter. I would then stick the screwdriver ( Or a piece of wire) inside of the hole to make sure that there was no pipes, or wire runing alongside the next rafter. Once I knew that the path was clear, then I would drill the hole. You might have to patch up several small holes alongside each roof rafter ( or floor joist) but it is well worth patching a very tiny small hole then drilling through a large waste pipe.

We use an auger bit 1 1/4 - 1 3/8 and the more solid extenions, I think they are 3/8". I like the kind with noches in the shaft where it couples to the next one to keep it from comming apart. Nothing worse then when your set up comes apart in the cieling. Oh ya, there is. If you drill thru the next floor or roof. Had some close calls. You want to drill as harizontal as possable. If your allready working from a hole cut in the cieling like a 6" can cut out you can't drill strait. It drills at an angle up. That will limit you to 3-4 joists. You can drill the same from the other side. Try to drill strait tward your target or it will make fishing harder.

Your not going to make 12' unless you have a large open space into the side of the joists like a garage or utility room. About 6' in the middle you will be short. I would just notch the bottom of the joist and drywall/plaster about 1" wide by 6". It' does not take much. Just enough for the wip and a strap to be under the finished cieling.

Some bit work better then others. I like the orignal auger cause it seems to cut on reverse. So it wount get stuck as easy. Sharp bits will help. If the angle drill gets too close to the drywall put a piece of cardboard between it. This will keep you from marking the cieling.

Try to listen and get a feel for what your drilling. If it takes too long to go thru you might be cutting into the prywood upstairs (too high). Any noise for contact with a pipe. Does not hurt to pull it out and check with a flashlight. Go upstairs and look to see where a bathroom is to warn you where pipes should be.

Maybe someone elce can do better with those deversabits but I don't like them.

Tom

Lost count of F.U.'s with a Diversabit. Stopped using them due to bad luck.

Here are some more memorable ones:
Hardwood floor
Lighting circuit
Water line
And my personal favorite, the house next door. Almost bought a pricey painting that day.

cvelectric, your idea seems fine to me. Put "No Patch or Paint" into the contract and tear up the cieling with a hammer if you want

Thanks for the tips. Tom I like the idea of notching the joists but I might just go with the hole saw idea since I have to pull a 30a. and a 20a. circuit together. Maybe I'll cut some drywall with the hole saw and screw the pieces into the joists to make it easier for them to repair. I did put in the contract that I'm not responsible for plaster damage. Thanks again for the great advice.

Hi,
What is above the ceiling? Another floor or some attic space?

If there is a low roof you may be able to make two access holes and fish up and over.

If there is a floor on top you have your work cut out for you.

I hate to say the word "Wiremold"?

Be careful when drilling blind! Copper water lines make great targets!

Regards

Greg

[This message has been edited by mustangelectric (edited 02-07-2005).]

Dversibit? UGH......

I hate em...

Spent hours laying out, "scouting" for pipes and wires only to have the bit deflect off a nail or knot and shoot up through the upstairs floor.

Lucky for me it was carpet.

I go with the notching of the drywall with nail plates from now on...

We all pride ourselves in doing as neat a job as possible with the least damage to the plaster or sheet rock. There is a point of diminishing returns however. It is often cheaper for a painter or taper to patch a bunch of holes then for you to spend hours trying not to make them.

-Hal

No chance of going parallel to the joists? That's the way it was usually done here in Europe. Two small holes (start and end of the run) and you're done.

As an engineer, I strongly advise against notching joists. The highest stresses in a beam are carried in the outermost fibers of the beam. When you notch a beam (joist), you are essentially reducing the depth of the entire beam by the depth of the notch. Say, converting a 2x10 into a 2x9.

The stiffness of a beam varies as the cube of the depth of the beam. So, in the case of a one inch notch in a 2x10, you're causing a 28% degradation in the stiffness of the joists. That's major damage to the quality of the floor above, and possibly a dangerous reduction in the strength of the floor.

It is also a violation of building code to notch the center 1/3rd of a joist or rafter.

Also, building code requires holes to be a minimum of 2 inches from the edge of the joist or rafter. Like the engineer said, the stresses in the wood is in the outermost fibers.

Notching the beams 1"?

That's a big area. Nm is what, 3/4" long, 1/4" thick.If you take out the drywall that is prob 1/2" thick, you only at best have to trim the bottom of the beam 1/4" deep to lay the NM in, then if you screw a steel nail plate on, how is this affecting the beam strentgh itself.

I've seen guys notch too much, which is silly, and Have seen guys drill holes in them "particle board" beams, which is a huge problem there.

I think Texas Ranger has the right approach. Why go thru all that risk and patching when you can just go the long way around? The intuitive thinking is to go from 1st base directly to 2nd base but you have maybe eight joists in the way. So you go from 1st to home to 3rd and then to 2nd with no joists, structural issues and patching. Romex is not that expensive.
Again, good point, Mr. Ranger.
~Peter
Another point. Does anyone make a borescope about 1/4" in diameter? It soes not need to be flexible but could operate like a little periscope.

Why go thru all that risk and patching when you can just go the long way around?

Huh? You have to go across a ceiling against the joists maybe to install some cans. How are you going to go around?

As an engineer, I strongly advise against notching joists.

Agreed. Notching joists is a result of trying to be neat at the expense of weakening the structure. Don't want to weaken the structure? Might as well (neatly) Sawzall out a 4" wide strip of sheetrock or plaster and drill the joists in the center as you would if the ceiling were open.

-Hal

I think hbiss got it. Just open one long 4" wide strip and drill the joist properly. The drywaller will have an easier time patching one long hole than a bunch a tiny ones. Plus you will be out of there that much faster. I like to use a vacuum and a rotozip in plaster. Don't forget to draw some straight lines as guides or you haven't done you or the drywaller any favors.

Remember, sheetrock is really, really, really cheap--like ~$6 sheet. There's an instinctive desire to "minimize the damage" by keeping the holes as small as possible. But the reality is more like what hbiss and kinetic said--it's easier to patch one hole that's 4" wide and 12 feet long. Just cut one or two strips of rock, slap it up there, and you're ready to tape and mud it. You've maybe got 75¢ worth of rock in the patch--there's not much point in spending another three hours carefully cutting a bunch of tiny holes so that they only need 25¢ worth of rock to patch all the tiny holes.


[This message has been edited by SolarPowered (edited 02-08-2005).]

We all know that the sheet rock ceiling is easy to cut and patch but what about the lathe and plaster cielings? I use a 4" hole saw and patch with a 4" hole saw cut of sheetrock. I find this burns through the hole saws very quickly though. Curious if there are any better ways to cut through lathe and plaster?

I use a 4" makita grinder with a thin diamond blade to cut thru lath and plaster. It makes a lot of dust but you can cut thru simular to a sawzall with out a lot of the vibration of a sawzall. Having a good shop vacuum hose next to the blade cuts way down on the mess.
Fixing lath and plaster is more expensive than drywall but over all is usually cheaper than spending hours trying to fit diversabits or a lot of extensions thru a small hole.

+1 for the "strip" method.

I like using carbide blades on a sawzall... if the lathe is loose, try mounting backing boards on either side of your cut - lengths of 1x3 mounted on the surface of the plaster (with long drywall bits to the joists) to keep it from shaking loose with the saw.

Make sure you have an exhaust filter on the shop vac, or a "near HEPA" filter for the dust!