the space im growing in is 15’ tall but the collateral load for the purlins is 3 psf. anyone know how to convert that to a point load? I have thread rod and beam clamps suspending unistrut but i’m over weight, i think. the square footage for the hanging structure is 67 sq feet… so does that mean 200 lbs is all that handle? if i distribute the weight over 125 sq feet would that make it 375 lbs that it can handle?..but using thread rod and hangers make it a point load,right? confusing… what about a frame structure to hold 9 1000 watt hoods(40 lbs each) plus 9 ballasts and a light controller? would a truss system like you’d see the lights at a concert hanging from be good?
I would probably just mount some channel that spans from wall to wall, or use a gantry of some sort.
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can you take some photos? trusses are always heavily over engineered, but they are also often built to ultra tight tolerances, 15ft… serious?
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Basically says single point load is 1/2 of full distributed .
What are you securing to ?
A pic makes for an easy way to figure this out.
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According to your diagram you show the building is a commercial build with iron.
Hang your threaded rod and unistruts from I beams. Don’t hang them from a angled bar joist unless it is properly laced to withstand the side pressure.
Ahhhhhh the Joy’s of construction
You can always use acoustical ceiling wire, tie to the purlins or bar joist and they make clips for the purlins if they don’t have holes.
A theatrical lighting grid will only exacerbate the weight problem unless you anchor it to load bearing walls or columns you place. A legit grid seems like overkill to me. But maybe that’s the easiest route.
I’d really like to see a picture of the typical truss and detailed views of any connectors/brackets.
Any reason the ballasts couldn’t be relocated to a wall?
yeah… i have them hung with purlin clamps and threadrod down to unistrut. but i think it is overweight because the buildings collateral load is rated 3 pounds per square foot. the area i have them hanging covers 66.7 ft and it is @377 pounds. unless i’m figuring the 3 psf wrong , i’m like 177 lbs over
it is you typical metal building… z purlins span 27.5’ and they are spaced every 5’. collateral load is 3 psf but using clamps and thread rod make it a point load rather than it being distributed. yeah ballast could be relocated but that would only save me like 50 lbs… still over weight by like 125… that is if i am figuring the load correctly… if the buildings collateral load is 3 psf and the points im hanging from equals 66.7 square feet… would my max load not be 200 lbs?
Can we get a picture of what these are hanging from. You are the only one that actually knows what it is. Share with us a picture please. I’m intrigued as to what we are actually talking about.
I’m used to looking at a blueprint or at the actual job at hand. The picture in the link you gave is a huge ass commercial building that is probably capable of hanging any light made from the I beams or the bar joists.
A snow load can be heavier than the weight your saying it can hold. I’d have to guess your numbers are off
It’s a question for a local structural engineer.
Could you come at it another route? Can you add partitions to the grow area, and use those to hang lights?
yeah, local engineers around here cost $2,000. no one will answer the question if i’m over weight… I have to contract their services… i have a mechanical engineer working for me now but he wont tell me either… says he can only help me with mechanical stuff… ridiculous… so worried about liability… half of the engineers wont even look at my place… for partitions i have to have full out metal studs and fire code sheet rock walls… like $6,000 per wall… and all of the stipulations i have to go by are being enforced on me like 6 months after being operational… at first… horticulture was allowed as a use in my building so thats what i said i was… all indoor, growing flowers! but they went and changed everything and said i have to redo everything for agriculture use and pay them $750 every year but on the building permit i still have to follow code for a warehouse…
What’s the cost per lineal foot for that light metal wall?
Maybe a fab shop can rig up freestanding light holders for a reasonable fee.
With legalization comes regulation. Such is the way of things.
I would, if it were me, try building a rack to hold them individually from threaded steel pipe, like 3/4 gas line. Just a basic wardrobe design. That way they are movable. I’ve done it for welding curtains that weigh 50 lbs.
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If I had a big open building I would use pallet racks to set up grow areas.
Its always on craigslist from people looking to get rid of it. Pretty cheap sometimes.
Can space any number of shelves any distance, will hold half a ton or more.
Hang lights off the top shelf
No need for engineers or permits…
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look if you have done it this way and u haven’t damaged any trusses, like no kinks or holes or nicks it will be fine, they are over engineered but built with tight tolerance.
this means the shape will hold 3-4 times what its says but they build them with such fine tolerances to cut down on material so u generally cant drill holes in them cut them kink them or their rating goes right down, you get me?
so take some photos of how u have clamped it and what trusses u are working with… 
absolutely, the way I would do it…
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Don’t do partitions.
Do racks or build columns to put box beams in between to hold lights.
Depending on height and again what it actually is racks may be cheaper.
