Lofty

Ok, so you have a customer who's ceilings are boarded using foil backed plasterboard which effectively screws a lot of the electronic detectors and they DO NOT want loads of holes made in it so that 'it looks like a second-hand dart board'. What's the best way of locating the joists so they can have downlighters fitted ?.

Keep your fins wet and your air dry.

Cirrus

Lift the boards above

Lofty

Hi Cirrus,
Could do. But they have laminate flooring up there. So I suppose they either pay us to do it or they do it themselves and we come back.

Best regards,
Lofty

Keep your fins wet and your air dry.

U Jay

Could try tapping on the ceiling with a screwdriver handle, I know it's primative but the tone changes when you hit a joist. Sorry best I can do this time of night.

Jurassic Spark

I normally tap the ceiling with the knuckle of my index finger and listen to the sound it makes. When it becomes a dull thud instead of a hollow noise you've found or are pretty near to the joist.

I use a laser line fixed to the ceiling to mark out the positions of the downlights, fixing it in a position to give suitable clearance away from the joist. I then make a pilot hole where the centre of the downlight is going to be and then stick a wire from a coat-hanger into the hole pointing it in four directions to make sure the joist is far enough away.

U Jay

I like the laser idea, keep 'em nice and straight. btw if ever you can't find a cable in a downlighter hole when the plasterers have chucked everything out of sight, try sticking your mobile phone up there and take some pics...works a treat!

Des 56

A joist finder (also refered to by its other name Hammer )
will soon let you know where its located

Lofty

Actually did it using the knuckle method and my laser line. Took some time but victorious in the end. Mind you the plumber wasn't happy about having the radio off so we could here the different 'tones'.

Keep your fins wet and your air dry.

London Luke

Once you have found 2-3 and worked out the "Spacing" etc it should be easier.

I have seen a very unusual method a few years ago !!
the plasterboard was held up with nails. this guy using some timber went around banging the ceiling until the little bits of plaster fell off the nails !!!. I must admit he did a good job and it took him very little time to make good after (decorator painting anyway)

jibtech

nice thinking with the nails and the mobile phone and the wire to check for clearance from the pilot hole

arent laser lines ace!

i want an endoscope they look brilliant and you can check out your own poop chute or a friends

http://i170.photobucket.com/albums/u...fiesta-sig.jpg