help locating rafters

I am no carpenter, I spend my time on the farmall forum so I need some advice. I need to hang a porch swing for my wife under the carport. How do I locate the rafters under the plywood? I know I need to go right in the thick of the rafter to support the weight. Thanks for any advice. This may earn me some time in the shop with my tractor.

In plywood I would look for screw heads, they should be visible unless there is a lot of paint over them. Once you have found them you can drill 1/8" holes on either side of the screw in a line to determine exactly where the sides of the rafter are. You can feel if the drill pops through the plywood into air or goes into wood.
Zach

Zach, thanks, good to see a friend from the other forum.

Get a 2 dollar plastic magnet "stud finder" from nearest hardware supply.

Could use the "tap" method. With a lightweight tool, tap the boards along the ceiling till the sound changes. If you are careful and listen, you can tell where the wood is above the sheathing.

Look for nails or screws, they might be finish nails so the head would be small. Drill or drive a screw in to confirm that it is there. If you make holes that you don't want you can fill them with painter's caulk and touch up the paint.

Probably be safer to just buy one of those swings with the frame already with it instead of trying to find a rafter to put hangers in. Will be no fun for her if you miss the rafter.

Most big box lumber stores carry a (stud finder) that seem to work good. Used one on a ramp project couple weeks ago.

when we built our new home last year i had the professional doing the siding to place swing hooks in the porch ceiling joists. the joists were doubled for this purpose, however, one hanger pulled out one day while my wife and i were in it. sudden unexpected and painful drop, luckily the other side held. so, make sure of some things; 1. use hooks designed for swings as they are heavy made, have a nylon roller to reduce friction and wear and quieter. 2. make sure the hooks are in the center of the joists and not on the edge of it. 3. make sure starter hole is small so as not to remove too much wood for the hook to bite into.
good luck and enjoy, nothing like a summer morning and a cup of coffee while sitting on the swing.

Can you get up overhead?

I just bad visions of the screw-in hooks pulling out of the wood.

If it were me I'd go up overhead and add blocking where you want to hang the swing and use hooks with nuts and big flat washers, through-bolting right through the rafter and blocking.

When I had my house built I had the carpenters double width the bottom of the rafter and put a small x with pencil where the center was on the ceiling.
I used the longest 1/2" eye bolt I could find and one side pulled out! With a couple of our good friends on it. Luckily no one was hurt.
The lag pulled out because as luck would have the lag went in right in the center of the two boards sandwiched together.
Next I had the carpenter take down a piece of the ceiling and I ran a threaded eye bolt through added washers and double nutted the rod.

Conventional framing, you have about 1 1/2" of each member to find center on, for a fastener to be installed, and if its a truss, it could be southern yellow pine, which is a bit hard and brittle, miss that center and the fastener will pull out prematurely. I have aligned center by sweeping from each side of the suspected framing member, making a mark on each side and centering between them, yet I do not recommend blindly attaching something a person will sit on, into framing I cannot see first, its asking for trouble, now or later.

A.) check to see the size of the member will support the load between the span, which is the swing and how many people, there has to be a reference for lumber, its an engineer function, but it would seem like overkill, overthinking, but also a safe thing to do, that is entirely up to you.

B.) if after reinforcing, doing some investigating, confirm you should have enough strength and that the fasteners will hold in what you have and remember the fasteners are going to be either in shear and or tension, one had best select the right fastener, do not use deck screws and or even some kinds of cheap lag screws, they can be pot metal, never trust them unless there is a astm designation and made by a reputable mfr.

C.) I got a call from a customer to repair a commercial overhead door at his building and what I determined was mentioned above, I have photos somewhere in this pc, lag bolt fastener off center, split the bottom chord of the truss, the whole thing could have come down, killed or seriously injured someone. Trusses are really not meant for extra loading anyway, especially from the bottom chord, yet people do it all the time, usually not excessive weight, likely no problem but that bottom chord carries most if not all the load and one has no idea what the limits are unless its calculated, checked out and confirmed by same. My fix was to open up the area, you should do the same, and inspect what you have. In this case I decided to make hangers out of steel angle iron, which spanned a couple of trusses each side, I drilled holes and installed threaded rod, used an angle over and under the bottom chord and literally clamped both angle iron sections to the bottom chord, this afforded me the rest of the attachment and firmly stiffened up the entire assembly holding that door, it eliminated further compromising the framing above.

Purely up to you how you do it, blindly nail or attach without inspecting the existing framing opens the possibly much further of what ever it is you are attaching, to fail, which while sitting in the swing could cause serious injury, do a seatdrop from that distance, you could cause a spinal injury, compress a vertebrae, I'm no doctor, or licensed P.E., just common sense to do the right job.

Thanks a lot. I think I will brace between rafters and then bolt to that. Probably use screws to fasten the braces between the rafters. I would think this would share the load and be firmer as well.

If you use eye bolts I would recommend nylock type nuts, I hung a swing with regular nuts and one came unscrewed after a while. With the lock nuts it has been years with no problems.
Zach

Zircon makes some handy little electronic stud finders. I've had one for about 20 years now, it was $10-$20 back then. It finds the ouside edges of the studs/rafters. I mark the edges on a piece of masking tape or a wide Post-It-Note so there are no permanent marks left behind.

Rafters are designed to support distributed loads, say 50 pounds per square foot over the whole roof. Concentrated loads require extra bracing. If adults use the swing the maximum load on your hooks could be between 150 to 250 pounds per hook with a 50 pound side load when it swings. To spread the load between 3 or 5 rafters, consider installing 2x4 or 2x6 braces to the bottom side of your plywood ceiling. Fasten the braces through the plywood into all the rafters with deck screws, dry wall screws are brittle and can snap. Still fasten the hooks into the center of a rafter.

All good info here when you get ready to install your swing , go to the junk yard an get 2 hood springs off of an old chevy truck and hook your springs to the eyes and the chains to the springs. You will have a much smoother ride.Rodney

Stud finder..$12 and up, Home Depot,Menards,Lowe.

use these with carriage bolts
hangers

Look for nail heads. The seams should be on a joist to keep the edges from sagging down, and that would be the easiest.

put you a 2x6 at bottom of rafters and then get an eight ft 4x4 and put on top of rafters, toe nail 4x4 and long eye bolts..this will spread the load to more than 1 or 2 rafters, double nut eye bolts

Again use care with any screws, most common modern screws used for wood framing you'll find are not rated for any shear loading, and are likely not to have much in tension. However, you may be able to source wood screws that will suffice, well worth finding the fastener that has some loading capability in shear, tension and has threads with the best pull out or failure values. I would assume you could "beef up" the framing, for that garage door repair I mentioned, I liked being able to span a few trusses to spread out the load, and being able to clamp down on that bottom chord, eliminated any free play, the swing will impose some kind of rotational forces, so I would want to anticipate that and incorporate what makes sense to stiffen and safely secure it above, I kind of overthink some things, and like overkill and substantial safety margins, especially when it comes to things like these.

I had to quit using stud finders....every time I turned it on it goes crazy!!!!lol