Installing a ceiling light

[swampydrill]

I'm looking to put a small 12" semi flush light fitting in my hallway, i bought a new light but when i got home i notice on the instructions that it says to be hung from a joist. The light weighs 3.5 kg, when i tap around the ceiling i struggle to find the joist. Would all light fittings be generally screwed onto a joist??, if not, this new light has a 6" span on it so i can cut the hole the hole in the ceiling a bit bigger, i could then slide into the roofspace a 1 1/2" x 1 1/2" x 12" piece of wood to spread the load, the light fitting would then be screwed into that. Would this be ok to have that 3.5kg load spread across the plasterboard?, if not, then apart from taking the light back are there any other suggestions.

Cheers

 

[bernardgreen]

Make a hole and using a bent metal wire coat hanger or other bit of bendable wire as a feeler feel for where the joists are and then fix to one of them.

The problem with hanging that much weight on plaster board is if there is vibration / movement in the plaster board from people walking on the floor above or from air pressure as the front door is opened and closed.

The effect of the weight is magnified by the movement of the plaster board and the board itself may slowly detach from the joists.

 

[Chri5]

Most modern builds have joists at 450 centres, most sparks position the cable dropping out of the ceiling near a joist if the previous fitting was heavier that a simple pendant lamp unit.

Then you have to consider cable position if the joist is away from where the cable is.

Get a fine flat blade screw driver. Push through the plaster and board every 30mm or so, since a joist is circa 55mm eventually you will hit wood and identify the joist position.

By using a small blade the 6 or so holes that you might miss the joist can be filled with a dab of filler. Don't use a drill which could damage any pipes or cable above.

Most of us use the back of a screwdriver, and tap the ceiling- about 90% of the time I'm accurate 1st time. Might one of your mates have a joist detector, I've never bothered but they are meant to be useful most of the time.

8lb in weight is a large baby, I wouldn't hang that without proper support. Imagine what it would do to someones head if it fell

There's no chance of going up a floor and lifting boards?

 

[wingcoax]

As already mentioned, try to find a joist BUT how old is your house? You may have a noggin fixed between the joists where the light fitting is. They were normally about 6inches wide(flooring offcuts) that would give more than enough security.

 

[PrenticeBoyofDerry]

If you have carpets fitted on the floor above and fancy lifting them.
The floorboards will almost certainly indicate where the joist are by looking at the positioning of the nails/screws that hold them down.
Then if you have carpets up and can't find a convenient joist for the fitting, you could lift a section of the floor and bang a noggin in!

 

[swampydrill]

Thats what iv'e down, i stuck a screwdriver round the light fitting and found no joist, moved the furniture around upstairs, lifted the carpet up and i see written on the floorboard, 'noggin here', trouble is they have put the boards down under the skirting board and in 1 section, no thought for anyone at all, just speed in finishing a job.

 

[ban-all-sheds]

Do you know where any pipes are?

 

[PrenticeBoyofDerry]

lifted the carpet up and i see written on the floorboard, 'noggin here', trouble is they have put the boards down under the skirting board and in 1 section, no thought for anyone at all, just speed in finishing a job.

You would expect the floorboards to be under the skirting.
Can you identify the area from above where the the light fitting is to go?
If so, lift that section of floorboard up, cutting at centre of joists, and down the tongue and groove of the floorboard.
This can be done by using a multi-tool as shown in BAS's post above or by the use of a circular saw, setting the depth of the blade to 18mm to avoid cutting in to pipes and any cables that could be in that area.
Also avoid cutting through any nails as this will damage the blade. If the boards are screwed down remove screws prior to cutting.
You will need a utility bar to help lift the boards.

 

[swampydrill]

All done, cut a small hole in the floorboard and found there was a noggin next to to cable, screwd my light fitting bracket into that and then screwed a small plate across the area where i cut the hole in the floorboard, thanks for everyones help.