Confused about roof rating 20lb sq ft. Snow vs Roof

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Old 01-03-17, 02:36 AM
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Confused about roof rating 20lb sq ft. Snow vs Roof

Estimate How Much Weight Your Roof Can Support. Unless the roof structure is damaged or decayed, most residential roofs, regardless of the location of the house, should be able to support 20 lb per square foot of snow before they become stressed

Basically, Googling says a roof can hold 20lbs per sq ft before it becomes stressed, regardless if it's talking about snow or not.

Googling snow weight says it weighs 4-20 lbs per cubic ft. It says average is 12lbs (wet snow).

We had 3' snow last year. With wind drift potentially 4+'. Plus we often get a layer of ice before and after a storm (much heavier than snow).

Ok so all that aside, forgive me if this is a dumb question but it says 20lbs per sq ft before a roof is stressed, so if I'm 170lbs and stand on a roof with my feet together as 1 sq ft (on a rafter or in between rafters, either way really), isn't 170lbs like 8X the max rating? Or it's meant to mean overall, like I'm supposed to lay down and become 170lbs over approx 2'x6' area meaning approx. 14lbs per sq foot?


Really I'm just concerned about the snow rating for Lifetime brand plastic storage sheds. The following shows their stock snow rating and with the extra kit, they all can hold 30lb per sq ft.

~$55 with tax and shipping, a kit brings an 8' wide Lifetime plastic from 23lb stock to 30lbs.
~$75 with tax and shipping, a kit brings an 11' wide Lifetime plastic from 16lb stock to 30lbs.
~$135 with tax and shipping, a kit brings a 15' wide Lifetime plastic from 16lb to 30lbs.


If I get plastic shed instead of building a really strong wood one (or just buying a nice used wood one plus hiring someone to transport it would only cost about half of what the materials cost to build a new one), if I get a plastic, I'm considering getting the snow kit plus even building a 2x4 wall frame inside it and putting trusses on that that press right up against the roof. I read these plastic sheds can warp in Summer though and then leak, but would be very quick and easy to put up a plastic shed.
 
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Old 01-03-17, 02:54 AM
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Is there a question here???....................
 
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Old 01-03-17, 02:48 PM
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forgive me if this is a dumb question but it says 20lbs per sq ft before a roof is stressed, so if I'm 170lbs and stand on a roof with my feet together as 1 sq ft (on a rafter or in between rafters, either way really), isn't 170lbs like 8X the max rating? Or it's meant to mean overall, like I'm supposed to lay down and become 170lbs over approx 2'x6' area meaning approx. 14lbs per sq foot?
 
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Old 01-03-17, 03:19 PM
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like I'm supposed to lay down and become 170lbs over approx 2'x6' area meaning approx. 14lbs per sq foot?
It's meant to mean overall. So if your roof is 10 x 20, it can theoretically hold 4,000 pounds.

I'm no architect, but this is designed so the rafters or other type of roof support won't deflect too much under load.

Walking or jumping on the roof is a concentrated load and that's different, you could fall through, keep us posted
 
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Old 01-03-17, 08:10 PM
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probably a MOD will remove the link?? But got good info for same question on another forum, just search the title if you ever stumbled upon this thread googling similar info and link is gone.

[Link to another forum removed.]
 

Last edited by ray2047; 01-03-17 at 08:37 PM. Reason: Remove link. Unedited copy to Archives.
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Old 01-04-17, 04:12 AM
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Yeah the link was removed. Gotta understand what we do here. We try to help DIYer's fix things and build things. You are blogging. References to other forum sources is not allowed.
 
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