Hanging something from wooden beam

[Errrm]

Hi,

I'm thinking about hanging a kickboxing bag in my garage from the ceiling, the bag will probably be about 6ft long and about 45kg. I don't know much about DIY but from what I understand a beam in the ceiling should be strong enough because the garage was built with a bedroom above it i.e. the ceiling is also a floor. Firstly the ceiling is plastered with I guess plasterboard underneath that, what is the best way to find a beam? Also the brackets I'm looking at tend to have only 2 screw holes, what sort of length screws would you recomend using?

Thanks
Errrm

 

[JerryM]

would agree the floor joist would be strong enough although it might be better to use a thick wood plate typ 50mm spanning say 2 joists as a precaution.

in terms of finding the joists which are likely to be 50mm wide it's not that easy.

the trouble is that electrical wires are often all over the place in the void. the best way would be to take up the floorboards above and spot drill from above either side to indicate the joist position.

if this is too much then trial and error is needed and a few holes to fill afterwards. tapping the ceiling should get you close enough to the joist. then use something thin and blunt (ideally a bradawl) to make a series of holes in the plasterboard until you locate the edges of the joist. DONT use an electric drill (because of the elec cables)

on screws i would like to use something like 10g by 3" but again cables may be passing through the joists a mid depth (typ 100 for a 200 joist) so would say max 2" (in case joist is 150). screws need to be fully tightened against the brackets and the brackets same to the plasterboard (to avoid any tendency for bending).