[RE-wrenches] Racking System - Identification Help

[Christopher Warfel]

Dave, I have several of these kicking around (or had).  I do think that 
it is an old Unirac product. The ones we have (had) though, have lag 
bolt holes along the long central axis about 3/4" from the raised 
mounting surface. Chris
On 6/3/2014 11:11 AM, Dave Click wrote:
> Jason, thanks for the comment! I agree that systems could connect to 
> just sheathing and stay on the roof- I think Zilla has a product that 
> does this too. My concern about wind resistance stems from the fact 
> that there appeared to be an engineer's stamp on the Unirac calcs with 
> lag screws and then something completely different was installed in 
> the field. It's likely that this installer has used this same mounting 
> system in windier coastal areas so hopefully their fastener selection 
> had some informed analysis... I didn't see any, though.
>
> And to be clear, I'm not looking to overrule another PE if it is in 
> fact an engineered system and it's just that the wrong set of plans 
> got submitted to the building department.
>
> DKC
>
>
>
> On 2014/6/3, 10:12, Jason Szumlanski wrote:
>> Dave,
>>
>> I can't identify your hardware, but I just wanted to comment on your 
>> comment about hitting rafters. There are products out there that can 
>> obtain the requisite load ratings without connecting directly to 
>> structural members. We have had systems engineered and permitted 
>> using Ecofasten products on low-slope roofs that fasten only to wood 
>> sheathing or metal roof materials in 170 mph zones in Florida (ASCE 
>> 7-10, FBC 2010). I'm not an engineer, but I've been told if there is 
>> adequate data on pull-out and shear, you can use that data to 
>> properly design a system without hitting rafters with the right 
>> number of attachment points. I don't like the looks of what you 
>> pictured, but it's plausible that it was an engineered system design. 
>> The permit drawings not matching... that is another story...
>>
>> If, for example, each of the six fasteners provide 100 pounds of 
>> pullout strength with a safety factor, that would be good for 12 sq 
>> ft at 50 spf uplift per attachment. 250 fasteners would be good for 
>> about 5kW of solar.
>>
>> Jason Szumlanski
>>
>> Fafco Solar
>>
>>
>> On Tue, Jun 3, 2014 at 9:06 AM, Dave Click <daveclick at fsec.ucf.edu 
>> <mailto:daveclick at fsec.ucf.edu>> wrote:
>>
>>     Hi all,
>>
>>     Anyone know what this racking system is? The permit drawings say
>>     Unirac with lag screws and Eco-Fasten flashings, which this
>>     pretty clearly isn't. I'd never seen this before, and I imagine
>>     this wind resistance is not quite the 140 mph that the installer
>>     claims it is. Of the ~250 wood screws holding this system down
>>     into the roof, I think six of them accidentally hit rafters.
>>
>>     Thanks!
>>     Dave
>>
>>
>>
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>
>
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-- 
Christopher Warfel, President
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
401-466-8978

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