What is the largest screw that stir into a 2" yawning truss? I have a choice of 2 stainless steel screw eyes that I...
I have a choice of 2 stainless steel screw eyes that I will be putting into an overhead plank in a single-story house built contained by 1973. Ine is a 5/16" x 2 7/8" rated for 250 lbs nouns and the other is a 3/8" x 4 1/2" long rated for 325 lbs. I'd prefer to use the larger diameter (3/8") but am concerned around what might split or weaken the shaft, especially if I'm going to put as much as 175 lbs on the screw eye. Any thoughts or considerations?
Answers: Not enough information to answer your grill.
You need to know:
- the depth of the roof joist (actually a joist or rafter), eg 2" x something (8", 10", etc.)
- the widest unsupported span between supports on the joist,
- whether any knots are close to the location you want to install the screw eye.
- how much unresponsive weight the joist is carrying very soon (eg a ceiling made from 1/2" thick sheetrock)
- is the existing strut a simple joist, or part of a truss?
If you own access inside the roof, you might want to consider using a "header" to spread the 175 lb load on your screw eye across two or three parallel joist. Use a 2x6 nailed across the tops of the joist, with the screw eye fastened to the 2x6 "header."
Pre-drill and you will enjoy no splitting problem and full strength can still be achieved. Use a 1/4 inch drill for the 3/8 inch screw eye.