I purchased a 12×20 barn shed kit from Builders Discount. The plans that came with the building are less than thorough. I’m ok with that with exception to the roof trusses. This is the only part I am hung up on.
I am somewhat stuck to using the plans for this building because I am using metal roofing. It appears that the rafter lengths are designed based on the height of the metal. The metal roofing is 5′ tall for the top/upper portion of the roof and 3’6″ tall for the bottom/lower portion.
I’ve attached the plans that came with the kit. It says for a 12′ wide building the lower rafter length is 3′ 3 1/2″, and the upper rafter length is 4′ 7 1/2″. I feel that I have to stick to these lengths because of the metal roofing that will go on top and I would like to avoid having to cut the metal. What is not included, and what I am stuck on is the angles at each end of the rafters and the gusset measurements.
I have found a few gambrel calculators online, but none of the ones I’ve found will take the data I have and give me the data I need. If I know, the two different rafter lengths for each side and the total width of the truss, isn’t this enough to figure out the angles and the gusset?
Additionally, there is no overhang. The truss is only as wide as the building. Side note, Builders Discount was no help at all. This is the only part of the build that I am stuck on, and I am ready to get this project going! Any help is much appreciated!!!
Need more info. You’ll need at least one more measurement. The rise and/or run of either the lower rafter or upper rafter.
I was afraid that there was at least one piece of the puzzle I was missing. I do not know that and I am not sure how to figure that out.
Thank you for commenting!
Those drawings are done to scale. Why dont you measure the angle?
Then draw the thing out full scale on your garage floor to see if it works or use scrap pieces to mock up one rafter.
If the mockup or full scale drawing dont work out 100% adjust angle as needed to get you to the 3′ 3 1/2″ and 4′ 7 1/2″
That sounds like a great plan Sawdust_Steve. I'll probably give that a try and make adjustments from there.
Or determine your own pitch using the provided diagonals as your measurement, so your metal will fit accordingly. Example, a common pitch for gambrel trusses is 20/12 on the low side. Using a 20/12 pitch with your diagonal measurement it’s a little under 2’ of run. Just use the remaining run for the top section and your provided diagonal measurement and it gives you a pitch between 4 and 5/12. Can probably round it off to a true 5/12 b/c you probably have enough metal to cover.
Thank you, jlyda! I'll probably give that a try. Gives me a good starting point! I appreciate your help!
My preference would be to cut rafters and not make homemade trusses as well. Especially, if you are building alone like I am right now with this virus BS going on.
Are the gussets pre-cut? You'd be able to grab the angles from there.