Gambrel roof framing question

[Johnny Generic]

Building a 12' x 16' shed with gambrel roof. Don't want the top part ( roof peak to top of side wall ) to be equal. Need to know what angles and length to cut the trusses to get a 4' center clearance from the top of the top plate to the center peak. Side walls will be 6'. I surfed around and could find anything helpful. Thanks in advance. Johnny Generic.

 

[nadogail]

You might experiment with scale model mock ups and then measure what you come up with.

 

[Skiff Builder]

After building the deck you can layout the roof lines right on the floor.

 

[MushCreek]

I always draw that stuff up in Sketch-Up (free). Lacking that, I'd draw it out on the deck, as suggested.

 

[kaymccampbell]

I drew mine with a level and a pencil, directly on the shed deck. 30 years later, the drawing is still there, if you look closely.
Although a gambrel roof can be any angles or length of leg, I was taught that drawing a half circle, the width of the intended roof, then making the points of the roof touch the circle, is supposed to be the strongest design. Not sure if it's true, just old timey "wisdom".

 

[matt_i]

Certain sets of angles and lengths look better than others. The old-time barn builders are a generation we don't have to ask. I would look for one online or locally which looks visually appealing and scale-measure the lengths that you can translate into your drawing.

With a CAD program all you need is the lengths of the edges of the two roof planes, there are two solutions that will allow it to all match up and meet in the center, assuming the width of the building is already known (and I think it is in your case). But only one of the two solutions actually looks like a barn

 

[jkuro]

Draw it full size on a concrete driveway with some chalk. Works every time.
A blacktop drive will work as well. Hose off when done.

 

[CraigStu]

I helped my brother build his house w/ gambrel roof. We built the trusses in the driveway. Had the wood ready to go, and just started laying it out til we got what he wanted. One tip; it's a pain because you have to move every truss out of the way but we found build the first one and build the second on top of the first. Then move the second away. Build the 3rd on top of the first. We started just building them and leaving them. We learned that by about the 4th, we were the victims of small errors adding up so the 4th was not close enough to matching the first.

 

[Bretny]

Theres a calculator for this. At least there was when I built my gambrel shed roof. Its 13ft across and has major head room in the loft.

 

[Bretny]

Here it is. I swear blocklayer.com has the best building calculators.

https://www.blocklayer.com/roof/gambreleng.aspx

Looks like at 12ft wide you will be 5ft4in at the peak. If your in an area that has rain or snow I would do a kick out on the bottom of the roof to keep the side of the building dry. That knockout dosnt need to be added to the gambrel truss prior to putting in place. If you get the right length boards and/or make one rafter the right length this could be just scrap