Is there a way to hang something heavy from the ceiling safely?

Washington Post

3 days ago

Q: I want to install a pull-up bar in my garage, which has drywall on the ceiling. How do I make sure the bar doesn't come crashing down on me?
A: Whether it's a pull-up bar, a big potted plant or any other heavy thing that you want to suspend from a ceiling, mounting it securely is essential. Forget about using plastic anchors or oversize plastic screws designed for fastening heavy pictures to drywall. You need to screw into the wood framing for the ceiling with long, thick fasteners known as lag screws. Their name comes from the screws once used to fasten metal bands to barrel staves, also called lags. Although the fasteners are often referred to as lag bolts, they are technically screws — with a pointed tip that sinks into wood, rather than a blunt, threaded end that fastens into a nut, as true bolts do.
The original lag screws had square heads, but today most have hexagonal heads. You can tighten them with a wrench or a hex adapter in a drill, without the risk of stripping the kind of recess found on the heads of ordinary screws. It's possible, though, to snap off the head of a lag screw if you use too much torque to fasten it. Using an adapter in a drill is safer, and an impact driver with an adapter or an impact wrench is even better.
Lag bolts tend to be much thicker and longer than standard screws, and the threads are coarse, with far fewer threads per inch. The thickness and thread design mean that lag screws can support incredible weight without pulling out. The 2024 edition of the National Design Specification for Wood Construction, which is used to guide builders, says a ⅜-inch lag screw can hold up 200 to 300 pounds per inch of thread embedded in the wood, and a ½-inch lag screw can support even more. The actual weight limit depends on many factors, including the type of wood being fastened to and whether the shaft is unthreaded near the cap, as many lag screws are, and whether that unthreaded portion is the full diameter of the screw or skinnier. The tip of the screw doesn't count when calculating the length embedded in the wood, nor does the distance the screw reaches through drywall.
According to the Help Desk for the American Wood Council, which helps develop and spread information about building codes, the best way to support a heavy load is by installing a hanger over the top of a joist, rather than screwing into its bottom edge. But installing that in a space with a finished ceiling would involve more work, and it would be nearly impossible in a situation where there is a floor above.
These nuances matter for engineering calculations, but for mounting a pull-up bar, a customer service representative for Rouge Fitness, which sells bars and other fitness equipment, said the advice is rather simple: Use ⅜-inch or ½-inch lag screws at least 4 inches long. Pull-up bars always have several attachment points, so each screw does not need to support the full weight of the gear and the person using it.
It's critical how you install the lag screws into the wood framing, or joists, that hold up the ceiling (or the floor above, if you are installing something in a basement). Ceiling joists are typically solid wood that's called 2 inches thick but is actually just 1½ inches thick. To carry the loads shown in engineering tables, the center of the lag screw needs to be away from the edge of the wood by at least 1½ times the diameter of the screw. So if you use ½-inch-wide lag screws, you need to attach them exactly to the middle of the joist edge. Using ⅜-inch lag screws gives you a little more wiggle room if you don't hit the exact center of the joist. A lag screw that's too close to an edge can split the wood and not hold.
Although it's possible to locate joists by tapping on drywall and noting where the sound deadens to a thud, for a critical situation like holding up something heavy, you would need to confirm the joist locations by drilling tiny holes to confirm where there is and isn't wood behind the drywall. Using an electronic stud sensor that pinpoints the centerline of the wood is much easier. Franklin Sensors ProSensor M150/X990 Stud Finder has this feature and also detects hidden electrical wires. It can scan through up to 1½ inches of drywall, an important consideration in spaces such as a garage where there may be multiple layers of drywall to keep fires from spreading.
Although there are newer-generation lag bolts known as structural screws that don't require pre-drilling, you do need to drill pilot holes for typical lag screws. Get a drill bit at least as long as the screws; if the pilot holes are too short, you can split the wood when you tighten the screws. Even if the joist itself still appears solid, there can be small cracks near the screws that will keep them from holding well. For ⅜-inch lag screws, a pilot hole 15/64-inch wide usually works well in framing lumber. For ½-inch lag screws, use a bit 5/16-inch wide. If you have an older home framed with old-growth lumber, which is harder than most framing lumber available today, you might want slightly wider pilot holes.
Before you attach each fastener, slip on a flat washer that has a hole the same diameter as the lag screw. Screws are like miniature clamps, with the threads into the wood being fastened to forming one end of the clamp and the screw head the other. Adding a washer under the head helps keep the clamping pressure tight. The screw needs to be turned in far enough to eliminate gaps between the screw head, the washer and whatever you are attaching. But once that gap is closed, stop turning or you risk breaking off the screw head.
Some pull-up bars come with expansion bolts for mounting. Expansion bolts are designed to work in masonry or concrete. For fastening onto wood, lag screws are the way to go.
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