# Can a chin-up bar be supported by just two of the four intended mounting points?

I would like to hang a chin-up bar on a drywall.

So far I'm lucky. I measured that the studs (dotted in the image) are 16″ apart.

The distance between the two lower holes in the frame (grey area in the image) are also 16″ apart.

But the two top screws are problematic.

Possible solutions:

1. Don't bolt the top two support points. Two 3/8″ bolts are plenty for supporting an average adult.
2. Use butterfly drywall anchors for the top two holes. They will not take much weight, but they'll at least provide a bit of stability in case someone decides to swing.
3. Neither (1) nor (2) is good enough. Cut out 3/4″ plywood about 18″ ✕ 18″. Bolt the plywood to the wall with four serious bolts, and then bolt the chin-up frame to the plywood (how? And will 3/4″ maple plywood be strong enough?).

Which would you use, solution 1, 2, or 3?

Update

Let me add a second diagram that illustrates how the weight is transferred.

Notice in particular that the frame consists, as is common, of a diagonal support that takes the load to the wall through compression.

This means that omitting to add lumber underneath the bottom part of the structure will result in either:

• if the lightly shaded U-shaped metal part is too weak, it will bend, or,
• if that part is quite rigid, the two bolts at the top will be subjected to an undue pulling (tension) force and that tension—likely equal to the full-weight of a (possibly swinging) adult underneath—will have to go through a single piece of two-by-four (the top one). Remember that there are no studs directly behind the two top bolts.

This means that in addition to the two pieces of lumber suggested in isherwood's solution, it may be necessary to add a third piece of lumber. That third piece need only be glued to the wall.

Which would you do? Would you:

1. Add a third piece of lumber, perhaps by just minimally gluing it to the wall, just enough for it to stay where it is,
2. Add two pieces of lumber vertically such that they cover the width from A to C, or,
3. Add a single piece of (plywood, perhaps) that acts as support for the entire frame?

Update 2

I'm giving up putting in all the details in one question. I posted a sequel here.

• Have you check that there is no electrical wires or plumbing pipes in the studs? Jul 30, 2021 at 20:44
• @crip659 That's a valuable hint. I haven't. But on second look, there is an electrical socket 1" from one of the two studs I intend to use. There is possible (likely) an electric cable running on the side of the stud. Still: 1- The electric wires will be running beside the stud, so I'm safe if I drill through the center, no? How do you check either way? Also: 2- It's a bedroom, and so there is almost no chance there would be plumbing pipes running, no?
– Sam
Jul 30, 2021 at 21:40
• Electric cables can often go though studs, before running down/up studs. Do not assume, because you probably want screws longer than 1 1/2 inch long. If no bathroom/kitchen behind or above, then less chance of plumbing. Drywall cheap to remove and/or replace with good plywood. Jul 30, 2021 at 21:55
• @crip659 Thanks. Another quick question: The stud-sensor I have only detects (lumber) studs. I see that other models also detect electric wiring, but are these so precise they will help me find out whether the electric wires are inside or just outside a stud?
– Sam
Jul 30, 2021 at 22:00
• Should be good enough to trace where wire goes. If no wire above outlet, should be safe. If wire goes up and across studs, need to place screws above or below where wire goes across, give at least half a foot from wire for safety. Jul 30, 2021 at 22:06