I need to build a brace to support this light fixture in my dining room.
The eyelet screws on either end should be attached to the existing ceiling joists. However, mine run opposite the direction that I need them to. My plan is to cut 2×8 supports and fasten them between the joists, then attach the eyelet screws into the new supports.
I am considering running a length of metal rod through the new supports so that I can hold it more firmly in place using washers and nuts on either end. Overkill? Would this add any structural benefit or just wishful thinking?
Do I need to leave a gap at the top of the supports for airflow? I am concerned about trapping heat from the electrical box in the cavity that I'll be creating. If a gap is needed, how much space should I leave at the top?
Any other concerns for mounting a very heavy lighting fixture?
EDIT: Clarifying one proposed plan:
Best Answer
You could attach blocking to the joists on both sides of the existing electrical box and bracing, etc.
By attaching the blocking vertically, you will maximize the weight capacity, but by attaching horizontally you can provide a larger area to "hit" with the mounting hardware. Both orientations should support the weight adequately. Sections of 2x4 mounted vertically would easily support the weight, but you might use 2x6 or 2x8 if you mount it horizontally to maximize the surface area.
Make sure the blocking is as tight as it can be between the joists (within reason) and the ends are nice and square, etc. then fasten with 3-3.5" construction screws through the joists. Mount the blocking so that the bottom surface is flush with the bottom surface of the joists.
Attach the "base plate" of the lighting fixture through the drywall to the blocking. You can use "old fashioned" looking lag screws to attach the block. These are available at BigBox, etc. and will match the ironwork on the fixture.