purlin

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novemberaudi

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Im looking for tips to hang a 200 lb encapsulated transformer from a roof purlin system.

I dont have purlin sizes. Is it better to span a piece of strut between 2 purlins, or is it ok to drill holes in the z purlin and suspend it from the bottom of one purlin.
 
We would have you have a structural engineer design something for you. Many roofs are only designed to hold the weight of the roof if no equipment is installed on it. What the OP is asking about is the 2x4's that run between the beams on a commercial roof.
 
cowboyjwc said:
We would have you have a structural engineer design something for you. Many roofs are only designed to hold the weight of the roof if no equipment is installed on it. What the OP is asking about is the 2x4's that run between the beams on a commercial roof.
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I don't think that is what he is talking about

Is it better to span a piece of strut between 2 purlins, or is it ok to drill holes in the z purlin and suspend it from the bottom of one purlin.
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I think he is talking about the "multi-zed" that Jumper posted. Ether way I wouldn't hang any thing with that weight unless I had the paper work in hand from an engineer.
 
And the engineer will almost certainly prohibit you from drilling holes in the horizontal section at the bottom of the Z and hanging stuff from it, since that will both weaken and twist that member.
Danger, Will Robinson!
 
200 pounds is pretty light for a transformer. Im John 120/240, spread that load over four points of contact. The distributed weight in pounds per square feet that the roof structure will see would be no different than a man walking across the rooftop.
 
Given how everything is designed and built now days, the design would not include that additional load. I was told that per the building code, that any loads hung from the bottom of a bar joist that exceed 150 pounds requires the structural engineer to sign off on the installation. I would expect that the limit would be even lower for this type of structure.
 
iwire said:
Its 200 pounds, if we consulted an SEs advice for every 200 pound item we hung we would never get anything done.
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Those purlins are probably spaced 4+ feet apart and will be on a slope, so the load could be putting a torque on the purlin as well as a shear load. The purlins in turn fasten to members at up to 20 foot intervals. I'd at least call the manufacturer for allowable loads that don't require an engineering calculation. This type of construction is usually in a pre-fab building, so the manufacturer should be easy to find out if it's new construction.
 
gadfly56 said:
Those purlins are probably spaced 4+ feet apart and will be on a slope, so the load could be putting a torque on the purlin
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Which is why I recommended using the correct hanger that is made to work on the angle.

To each their own but we would hang a 200 pound load without engineering involvement.
 
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