Plywood and dimensional lumber gambrel trusses?

Started by IHDiesel73L, December 30, 2021, 10:15:11 AM

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IHDiesel73L

I've seen these types of gambrel trusses discussed from time to time with various opinions of how well they work and how strong they are or can be if built in a certain way.  The first time I had ever encountered them was in a factory built shed that my dad purchased years ago.  It's 14'W x 18'L with 6' side walls framed 24" OC and has 24" OC trusses made from 2x4s and plywood gussets which are stapled.  Its probably close to 30 years old at this point and has seen 2-3' of heavy wet snow sitting on the roof a few times in its life (located in New Jersey-ground snow load for the area is 30lbs/psf) and the trusses have not sagged and the walls have not bowed.  When the shed was purchased there was nothing tying the trusses together at the bottom and aside from a small (4' or so) loft that my dad put in himself at the back end there still isn't.  I'm considering a slightly larger (16'W x 20'L) to use as a sort of guest cabin/office on my property but the construction would be identical.  This company ( https://www.pinecraft.com/amish-made-classic-large-gambrel-barn-panelized-kit.html ) sells them in panelized kits which are reasonably priced and according to their website the structure is rated for 120MPH wind load and they will supply any necessary documents for permitting in your state.  Presumably somewhere, some how, some engineer has run the calculations on all of this and blessed it with a raised seal.  I haven't been able to confirm the finer details as they are closed until Tuesday.  I figure I could either purchase the panelized kit or just build it myself as the photos on the website and the dimensions are all that would be needed in order to duplicate the construction.  For good measure I would probably use 2x6s rather than 2x4s and high quality (no voids, etc...) 3/4" plywood for the gussets along with glue.  I'm interested to hear what others think of this construction method.  I will also follow up with whatever I hear regarding engineering documents, etc...after the 1st of the year. 

Don_P

Hmm, I see those blown out pretty frequently. Notice they say it is designed for 120mph wind, off the top of mind that is around 20 psf, your snow load is higher, I'd be questioning that. A tie across the joint from the heels of upper rafter to upper rafter would greatly increase the strength.


WISteven

DIY all the way.  That's not even 1K of lumber.