Alternative for one-way sheet metal screw

child-safetyfastener

I need to choose the right screws to install a child window guard into a wooden window frame.

The guard comes with one-way screws, but my 9 month old hasn't figured out the trigger on my Dewalt, so I want to use normal screws. I called the manufacturer but they are "unable to recommend screws other than those provided."

The screws look like 1" #10 sheet metal screws with either pan or truss heads (also below). This is a little odd because they recommend them even for wooden window frames.

The guard is constructed of square steel tubes with 3/8" holes on one side and 3/16" holes on the other (see below). The screws attach the guard to the window frame by passing first (and entirely) through the 3/8" hole, the threads and shank pass through the 3/16" hole and into the frame, and the head presses up against the inside of the tube around the 3/16" hole.

Screw heads
Screw transverse
Guard tube

If this were any other application (i.e. one that isn't for preventing my child from falling to his death), I'd just get a round-head wood screw and call it a day. Instead, I don't know how to decide between:

  • Round-head wood screw (since it's going into wood)
  • Truss- or pan-head sheet metal screw (since that's what they provided)
  • Roofing screws (since they are designed for attaching metal to wood)
  • Something else I haven't thought of

What say you, oh wise DIY Stack Exchange?

— Sal
smile.

Best Answer

Round-head wood screw

OR

Truss- or pan-head sheet metal screw

Either one will work fine. The stresses on that screw would likely be minimal and would be tensile rather than shear, so use whichever one is easiest to find in a 3/16" (#10) diameter with a head that fits through the outer hole.