Hanging a heavy porch swing - PeachParts Mercedes-Benz Forum

sunedog · #1 06-29-2015, 05:03 PM

I built my wife a hanging day bed and need to hang it from the porch ceiling.

I figure the bed with mattress and pillows weighs around 100 lbs. Knowing my friends, at some point there will be up to 5 adults on it for a photo op. (No, we are not swingers and the 5 adults will be clothed and not engaged in vigorous motion, Aklim.) 5 adults at an average of 180 lbs (the girls are more likely 110 to 140, the guys may push 200) total up around 800 lbs. So this contraption may at some point be close to a 1000 lb live load.

I built my porch with 2x6 #2 grade SYP ceiling joists on 16 in centers spanning right at 10 feet. Span tables tell me that dimension joist will span 12' 0" with a 20 lb per square foot live load.

The ceiling joists run perpendicular to the orientation of the swing in the picture above.

I plan to attach 4x4's above the joists and perpendicular to them and attach heavy duty through bolted eye bolts to the 4X4's. The 4x4's will be long enough to span three joists, so essentially the weight will be shared by three joists on each side.

How can I calculate how much weight three of my joists will carry?

Note: My original plan was to double up the key 2x6's with plywood and construction adhesive, but I have figured out it is not possible to get new 10 foot long joists into the space without unreasonable additional demolition.

panZZer · #2 06-29-2015, 05:34 PM

Quote:

Originally Posted by sunedog

I built my wife a hanging day bed and need to hang it from the porch ceiling.

I figure the bed with mattress and pillows weighs around 100 lbs. Knowing my friends, at some point there will be up to 5 adults on it for a photo op. (No, we are not swingers and the 5 adults will be clothed and not engaged in vigorous motion, Aklim.) 5 adults at an average of 180 lbs (the girls are more likely 110 to 140, the guys may push 200) total up around 800 lbs. So this contraption may at some point be close to a 1000 lb live load.

I built my porch with 2x6 #2 grade SYP ceiling joists on 16 in centers spanning right at 10 feet. Span tables tell me that dimension joist will span 12' 0" with a 20 lb per square foot live load.

The ceiling joists run perpendicular to the orientation of the swing in the picture above.

I plan to attach 4x4's above the joists and perpendicular to them and attach heavy duty through bolted eye bolts to the 4X4's. The 4x4's will be long enough to span three joists, so essentially the weight will be shared by three joists on each side.

How can I calculate how much weight three of my joists will carry?

Note: My original plan was to double up the key 2x6's with plywood and construction adhesive, but I have figured out it is not possible to get new 10 foot long joists into the space without unreasonable additional demolition.

Tear this apart and re-do it out of carbon fiber tube, then get a sensible weight futon mattress.

MTI · #3 06-29-2015, 05:56 PM

I can't say about the free load, but the framing for the mattress seems to be a bit overkill lumber-wise. Curious, what is the virtue of having it suspended? It's not really a swing. If it is, consider the utility of having steel mounting points on the ceiling joists.

aklim · #4 06-29-2015, 06:29 PM

Quote:

Originally Posted by sunedog

I figure the bed with mattress and pillows weighs around 100 lbs. Knowing my friends, at some point there will be up to 5 adults on it for a photo op. (No, we are not swingers and the 5 adults will be clothed and not engaged in vigorous motion, Aklim.) 5 adults at an average of 180 lbs (the girls are more likely 110 to 140, the guys may push 200) total up around 800 lbs. So this contraption may at some point be close to a 1000 lb live load.

If the several people sit on the swing and the others on the floor doing whatever, it could be ok.

To decide, I think we should see the girls' pictures. Did you take clothing weight into account? Maybe less clothing will decrease load?

P.C. · #5 06-29-2015, 06:34 PM

Quote:

Originally Posted by aklim

If the several people sit on the swing and the others on the floor doing whatever, it could be ok.

To decide, I think we should see the girls' pictures. Did you take clothing weight into account? Maybe less clothing will decrease load?

^^^Bob Guccione, ASME...

t walgamuth · #6 06-29-2015, 06:55 PM

hang it from four points. Put a 2x6 flat above your ceiling and run it as far as you can across joists. Are your joists supported by wood or are they hanging on nails? Nails are ok if you are using joist hangers.

If you are well supported, then put your through bolts about 3/8" up through it all with a nut and big washer above and below the wood framing/ceiling. Run a 2 x 4 on either side of the bolt or put in a 4 x 4 as blocking and drill through it.

The porch roof is designed for a snow load (if to code and if in not warm areas of the country), and your bed swing will be less than the snow load and you won't use it in the winter anyway.

I agree that the frame is way over kill, but the extra weight is insignificant.

Looks pretty nice!

P.C. · #7 06-29-2015, 08:02 PM

Quote:

Originally Posted by t walgamuth

hang it from four points. Put a 2x6 flat above your ceiling and run it as far as you can across joists. Are your joists supported by wood or are they hanging on nails? Nails are ok if you are using joist hangers.

If you are well supported, then put your through bolts about 3/8" up through it all with a nut and big washer above and below the wood framing/ceiling. Run a 2 x 4 on either side of the bolt or put in a 4 x 4 as blocking and drill through it.

The porch roof is designed for a snow load (if to code and if in warm areas of the country), and your bed swing will be less than the snow load and you won't use it in the winter anyway.

I agree that the frame is way over kill, but the extra weight is insignificant.

Looks pretty nice!

It's the W140 of hanging day beds!

sunedog · #8 06-29-2015, 09:23 PM

Quote:

Originally Posted by panZZer

Tear this apart and re-do it out of carbon fiber tube, then get a sensible weight futon mattress.

Haw! You funny man.

Quote:

Originally Posted by MTI

I can't say about the free load, but the framing for the mattress seems to be a bit overkill lumber-wise. Curious, what is the virtue of having it suspended? It's not really a swing. If it is, consider the utility of having steel mounting points on the ceiling joists.

The framing was done with about 5 adult capacity in mind. I started with 4x4's and ripped them down to a slightly more aesthetically pleasing 2 3/4" width and chamfered the vertical edges. And, Dude, it is a hanging bed. Anyone can build a bed. This one floats.

sunedog · #9 06-29-2015, 09:29 PM

Quote:

Originally Posted by t walgamuth

hang it from four points. Put a 2x6 flat above your ceiling and run it as far as you can across joists. Are your joists supported by wood or are they hanging on nails? Nails are ok if you are using joist hangers.

If you are well supported, then put your through bolts about 3/8" up through it all with a nut and big washer above and below the wood framing/ceiling. Run a 2 x 4 on either side of the bolt or put in a 4 x 4 as blocking and drill through it.

The porch roof is designed for a snow load (if to code and if in not warm areas of the country), and your bed swing will be less than the snow load and you won't use it in the winter anyway.

I agree that the frame is way over kill, but the extra weight is insignificant.

Looks pretty nice!

Thanks, Tom. This is the kind of reasoned response I was looking for. The ceiling joists bear on solid structure on both ends. I like your idea of the 2x6 on the flat. The 4x4 I was planning to use may be overkill and it definitely introduces additional challenges (like finding a 12" long eye bolt with enough threads to penetrate a 4x4 with a bolt and washer above and below the 4x4.) The house is in central SC so rarely get snow.

sunedog · #10 06-29-2015, 09:38 PM

And I think I figured it out driving home from work.

The 2x6 is rated to carry 20 lbs per sq ft at a 12 foot span. In my simple mind, I am imagining a single 2x6 spanning 12 feet with a row of 1 foot by 1 foot squares on them. Each square is 20 lbs. So twelve of them weigh 240 lbs. Therefore, a single joist can carry 240 lbs with acceptable deflection.

Since I am planning to hang the swing from four eye bolts attached to 2x6's or 4x4's perpendicular to the joist span and going on top of three joists, they should be able to carry 3 X 240 lbs, or 720 lbs. Each side of my swing may weigh up to 500 lbs, so the three joists should not be over stressed since three joists should be able to carry 720 lbs.

(Actually more than that since the math I am using is based on a 12 foot span and my actual span is 10 feet.)

aklim · #11 06-29-2015, 09:40 PM

Quote:

Originally Posted by sunedog

Haw! You funny man.

The framing was done with about 5 adult capacity in mind. I started with 4x4's and ripped them down to a slightly more aesthetically pleasing 2 3/4" width and chamfered the vertical edges. And, Dude, it is a hanging bed. Anyone can build a bed. This one floats.

Ok. You are building a swing and you are not swingers?

Why 5? What happens when one of the oddballs gets a significant other?

t walgamuth · #12 06-29-2015, 11:05 PM

Quote:

Originally Posted by sunedog

And I think I figured it out driving home from work.

The 2x6 is rated to carry 20 lbs per sq ft at a 12 foot span. In my simple mind, I am imagining a single 2x6 spanning 12 feet with a row of 1 foot by 1 foot squares on them. Each square is 20 lbs. So twelve of them weigh 240 lbs. Therefore, a single joist can carry 240 lbs with acceptable deflection.

Since I am planning to hang the swing from four eye bolts attached to 2x6's or 4x4's perpendicular to the joist span and going on top of three joists, they should be able to carry 3 X 240 lbs, or 720 lbs. Each side of my swing may weigh up to 500 lbs, so the three joists should not be over stressed since three joists should be able to carry 720 lbs.

(Actually more than that since the math I am using is based on a 12 foot span and my actual span is 10 feet.)

Good thinking.

sunedog · #13 11-04-2015, 08:18 AM

Follow up. Now maybe you'll understand why I beefed up the swing structure. Gave it a test the other night with 6 medium size adults. It came through with flying colors. Nary a creak from the swing or the ceiling joists. Was a very comfortable place to hang out with close friends for a few hours on a beautiful chilly night.

t walgamuth · #14 11-04-2015, 09:21 AM

Cool! Looks like you gave it a real test. I did not reckon on six adults!

Yikes!

Txjake · #15 11-04-2015, 09:34 AM

what was going on under that blanket?