avoiding wires in joists

[talisker]

i'm planning on putting some hooks in the garage joists to hang bikes from ,the ceiling is plastered as there is a bedroom above i'm fairly sure there are wires somewhere in between that i will obiviously need to avoid.
i can't check from above as there is a laminate floor down so other than poking holes everywhere in the ceiling is there any other way of checking, i've seen a device that detects joists and wire but wondered if they actually work ok

 

[scarypants]

There are devices that can detect cables and voltage within ceiling voids most only work over a specified distance within the material it's self.
Some are better than others not come across a really good one. How long is the thread on the hooks?

 

[talisker]

the thread is about 3" long

 

[ban-all-sheds]

How deep are the joists?

And how old is the building? Old enough for asbestos to have been used in the garage ceiling?

 

[Steve]

poking holes everywhere in the ceiling

I know you were probably joking, but dont do this, its a fire rated ceiling which will stop your bedroom catching light for half an hour if your garage goes up.

 

[ban-all-sheds]

i've seen a device that detects joists and wire but wondered if they actually work ok

The good ones work pretty well at detecting joists - is your problem that you don't know where the joists are?

I doubt that any of them will be able to tell you how far from the top and bottom surface of the joists there are holes for cables, and where there are cables running at right angles to the joists the cables will not be resting on the ceiling, so even a good detector that finds cables won't find them. And even if you can locate cables on the ceiling where they run parallel to the joists you still won't know where they run through them.

Basically I think you're stuffed - you'll not be able to find out where you can safely put those screws in. I suggest you forget the whole idea - install a beam below the ceiling, supported on brackets/plates fixed to the garage walls, and screw your hooks into that.

 

[mikhailfaradayski]

If you can find the joists by tapping on the plasterboard to 'feel' the difference between hollow and solid parts of the ceiling.

Assuming that the joists are 6" deep, there is unlikely to be any cable located closer than 2" to the bottom edge of the joist, then add about half inch for plasterboard.

If you dont pierce the plasterbosrd by more than 2" then all should be good!

Still, i'd be a bit worried about using a 3" screw hook. Might want to consider using battens to spread the load and then more, shorter hooks

 

[Taylortwocities]

Assuming that the joists are 6" deep, there is unlikely to be any cable located closer than 2" to the bottom edge of the joist, then add about half inch for plasterboard.

You are assuming that we live in a perfect World. Theoretically cables should be a minimum of 50mm but in reality they can duck and dive all over the place.

 

[mikhailfaradayski]

If thats the reality, as you put it. Then i might suggest the reality is also that its been a bodge job from the start.

The only times i've seen cables run under the joist , buried in the plasterwork, is when its been a very rough DIY mod.

I'm most certainly not suggesting i think we're in a perfect world.

but there is good, bad, ugly and downright dangerous!

 

[Taylortwocities]

Per Forrest Gump

Life's a box of chocolates, you never know what you're gonna get

 

[mattylad]

go for it, screw the hooks in - just wear rubber gloves when doing so

 

[mikhailfaradayski]

you'd have to be pretty unlucky to find a cable in floor joist from the underside with a 2" screw.

I wouldn't say the same is true at the top though.

But still, if your that worried, please put your marigolds on