I want to hang a motorized projector screen on my basement ceiling. I'd like to know how much weight I can safely hang from the ceiling (joists? See picture below. Arrow marks the spot I'd like to drill/screw at). There's one such structure in the ceiling every 20 inches.
The screen weights 50 lbs and would be hanged from each end. So, 25 lbs on each end.
How do I determine if it safe to hang that and how do I pick the right screw size and length ?
If it makes any difference this is a Montreal house and there's 2 more stories above the pictured ceiling. The room is 18' long, but I don't know if there's a beam or anything midway to hold this joist.
Best Answer
Before you drill those trusses, I’d be careful because: 1) they are floor (not roof) trusses and carry a significantly larger load than roof trusses, 2) there’s another floor and roof above, and 3) that load will put the bottom chord in “double bending”, which can cause failure.
1) The load looks like it’s being applied at or near the mid-span, where the greatest deflection (bending) occurs. If you could move it to within 1/3 the span of the trusses, it’d be best.
2) I’d check to see what is “loading” the floor above. Some activities have less loading and some are extremely high. Storage (especially book storage), waterbeds, refrigerators, tubs, etc. are “high load areas”. Bedrooms, hallways, open areas, etc. are low load areas.
I’d check to make sure a wall perpendicular to this truss does not support the roof.
3) Any load on the bottom chord will put “that chord” in bending. Very dangerous...especially because you’re adding it mid-span between two chord fasteners. I’d move it as close to the web joint fastener as possible.