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I have a 2-car garage (22') with a finished ceiling in our new house. Above the garage is a large bedroom. I went to hang the kayak from the ceiling in the garage, but I was getting unexpected readings when finding the joists on the finished ceiling. My stud finder gives a width for the joist, and it says 3 inches. I drove in nails on each side of the joist to try to find center and the nails from edge to edge are about 3.5 inches apart. I expected the joists to be 2x10s since there is a room above it (and the first floor uses all 2x10s). I am wondering if these are I-Joists or 2 2x10s stacked together or trusses. I have spot checked around, and everywhere I checked in that ceiling with the stud finder is showing the same thing. There is a garage door opener and the tracks and opener itself are all mounted to the ceiling using lag bolts from what I can see.

I don't want to put lag screws and lag eye bolts into an I-Joist, and if it is a truss I don't know what size, so I am pretty much just at a loss here on what to do. Is there a way to determine what my joists look like without just cutting a big hole and looking?

The plan was to hang a 150lb fishing kayak from the ceiling with 4 mounting points in the ceiling (2 pulleys and 2 eye bolts). I planned to secure the pulleys using a 3.5" GRK deck screw. The eye bolts are 5/16"x4" lag screws. The joists run perpendicular to the desired mounting direction so each mounting point is in a different joist/truss.

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    New house - get the plans from your builder. Possibly a 2x4 truss structure.
    – Ecnerwal
    Nov 30, 2022 at 11:58
  • 150lb total weight / 4 mounting points = >40lbs per mount. Of course, there's the dynamic load to consider (pulling on the rope to hoist it up), but that's not a significant amount of weight to be borne by each mount. To confirm, though, you'll have 2 static mounts (the eye bolts) and 2 dynamic ones (the pulleys)? Also, "a 3.5" GRK deck screw" does seem a bit minimal for the dynamic side of the load - I presume there will be more than one screw holding the pulleys up?
    – FreeMan
    Nov 30, 2022 at 12:44
  • Oops.. that was supposed to be < 40 lbs/mount, not >. You get the idea...
    – FreeMan
    Nov 30, 2022 at 14:53
  • The plan for each pulley was a single GRK 3.5" rugged structural screw. The rating for pull out force was about 5x more than the entire system, so I was thinking it would be more than ok even with the dynamic load, but I am not an engineer so I'm basically just guessing. Because the kayak is perpendicular to the joists, I can only safely install 1 lag/screw per pulley without coming up with a different setup altogether.
    – Joe
    Nov 30, 2022 at 16:38

1 Answer 1

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Sometimes you just need to cut an access hole so that you can see what's up there. I'd do that just to be sure.

But regardless of what the construction is, adding 150 lbs. of weight is going to be insignificant here. So the only concern is to get it properly and securely anchored so that it doesn't come loose and drop the kayak.

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    My thinking is if it is a truss this wouldn't be a problem since it is a small load across 4 trusses. I think I'll go buy a $30 borescope and try drilling a small hole to see what I'm working with.
    – Joe
    Nov 30, 2022 at 2:53
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    Unlikely to be a truss since there is a living space above it according to the OP.
    – jwh20
    Nov 30, 2022 at 2:54
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    Floor trusses exist. They are even common when spanning 22 feet. Truss does not imply "roof truss"
    – Ecnerwal
    Nov 30, 2022 at 11:59
  • newly viable option: you can buy endoscopes that connect to phones (usb-otg) and laptops for <$10 (ebay) or <$20 (amazon) shipped. They aren't the best image quality, but they only need a 1/4" (6mm) hole and are more than good enough for tasks like this.
    – dandavis
    Nov 30, 2022 at 23:31

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