Hanging Daybed

[gregt]

I have completed a daybed and am now ready to hang it on my back screened in porch.
The ceiling joists are 2x10 and a tripled up two of the joists where I will be hanging the daybed .
I plan to use 4  3/8 or 1/2" x 6"  lag eye hooks to go into the center 2x10 of my triple 2x10 beam.
How can I determine if the lag eyebolts are strong enough. One chart I researched showed that the pull out capacity of a 3/8 diameter lagscrew is 450lbs per embedded inch. So that would compute that each 6"lag could support 2700 lbs.
The daybed weighs approximately 200 lbs and with 2 adults the total weight could be 600 lbs.
It therefore seems that the 4 lag eyebolt should be adequate.
Any advice?

[flyingvan]

If two 200 pound people, in a fit of passion, were to take a flying leap of 3' onto one corner of your hanging bed---accounting for some deceleration spread out by a mattress---plus the static weight of 1/4 of the bed, I get 1650 pounds on a single lag bolt.  Heavy weight, more passion and a higher leap would greatly increase that force

[ChugiakTinkerer]

My preference would be to through-bolt into the joist with a 10" threaded eye bolt with washer and nut on the top side.  That way you have wood in compression holding the bed up.  If you can't get to the top of the joist then perhaps use swing anchors?  Ones like these can give you a lot more inches of grabbing thread: http://trampolinepartstore.com/products/porch-swing-hanging-anchors-set-of-2

The tensile strength for a lag screw is very much dependent upon the wood in which it is threaded.  On page 77 of this document there is a table showing the withdrawal design values for lag screws.  If your joists are of wood with the lowest specific gravity in the table, a 3/8" lag screw is good for 149 lbs per embedded inch.  Keep in mind that a 6" lag screw may only have about 3.5" of thread.  So worst case that screw is good for about 525 lbs.  More inches of threaded screw holding up your bed will be much better, so either anchors or longer screws with full threading will do that for you.

[MushCreek]

I made brackets out of 2" angle iron, bolted to the side of doubled joists. I left an 'eye' sticking out when I paneled the ceiling. I'm paranoid about these things; I suspect that mine would hold thousands of lbs.

[Don_P]

That is much stronger with the wood connections in shear rather than in withdrawal. One detail you'll see often repeated in the NDS and other publications is to make the connection above the neutral axis of the beam (above the midline) so that it is not trying to pull the lower fibers apart. For porch swings I'll often put a 4x4 across the top of a few ceiling joists and run a long eyebolt up through it with washer and nut.

Thousands of pounds of load and 3' flying leaps... is the porch up to these goings on?

[Adam Roby]

If two 200 pound people, in a fit of passion, were to take a flying leap of 3' onto one corner of your hanging bed---accounting for some deceleration spread out by a mattress---plus the static weight of 1/4 of the bed, I get 1650 pounds on a single lag bolt.  Heavy weight, more passion and a higher leap would greatly increase that force

I think I'd be afraid to visit you unannounced...