First barn - need some advise

I am designing a barn (16x32) for our cabin in the woods. The construction will be 2x6, 16" OC. I want to put a gambrel roof on the structure and add a couple of lofts (one on each end). I need the center open for the storage of a canoe (i have a pulley system for storing the canoe off the ground, near the top of the roof/ceiling. As such, i can't use collar ties on the rafters.

My questions is, what is the best way to secure the rafters to the walls/top plate so everything is secure?

Hi Bill,

Welcome to Permies.  

To stress a point, you are talking rafters and not trusses.

I built a similar sized cabin in MN. I had a shed roof.  I toe nailed the rafters to the top plate. For added security, I also used hurricane strapping.  I am sure you will get a variety of answers.

The type of cut is called a "rafter seat." Be sure to use hurricane ties to connect the rafters and top plate. If there are to be no collar ties in the open area, you will probably want to make sure there is a full ridge beam and plenty of purlins that span the open section and overlap onto several rafters on either side. If possible, in the open section maybe just use shorter collar ties and have the canoe hang just a bit lower, or do a scissor truss for the rafters in that section, which will give a lot of strength without as much height loss as a collar tie.

Welcome to the forum!

I believe the assembly of pieces for a gambrel roof is referred to as a truss but I could  be wrong.

John F Dean wrote:Hi Bill,

Welcome to Permies.  

To stress a point, you are talking rafters and not trusses.

I built a similar sized cabin in MN. I had a shed roof.  I toe nailed the rafters to the top plate. For added security, I also used hurricane strapping.  I am sure you will get a variety of answers.

I hadn't planned on a ridge beam. Why is that needed if I build the roof sections with gussets (like all of the plans I've seen use)?

The hurricane hangers is a great idea. We used those in Florida all the time for roofing (code requires them) but I didn't think of them here in New Hampshire. Where do purlins fit in this build?

We will be sheathing the roof with 1/2" plywood or ZIP board (haven't priced either out, yet) and then topping that with a steel metal roof. I want to be sure snow sheds off this thing really easily.

Abe Coley wrote:The type of cut is called a "rafter seat." Be sure to use hurricane ties to connect the rafters and top plate. If there are to be no collar ties in the open area, you will probably want to make sure there is a full ridge beam and plenty of purlins that span the open section and overlap onto several rafters on either side. If possible, in the open section maybe just use shorter collar ties and have the canoe hang just a bit lower, or do a scissor truss for the rafters in that section, which will give a lot of strength without as much height loss as a collar tie.

There is a difference between a rafter and a truss.  Rafters are put in place during the build. The boards are heavier that those used for trusses.  Rafters normally allow for useable attic space.  A rafter supports the roof and is separate from the ceiling joists that support the ceiling. For example, the rafters on my cabin were 2x12s.  I enjoyed ample attic space.

Trusses are often built under climate controlled condition. The boards are smaller. The supporting members reduce useable attic space.  The roof and ceiling supports together as well as the connecting supports make up the truss.  For example, the trusses on my house are made up of 2x6s and 2x4s.  I have barely enough room to squeeze through the supports.

Either rafter or truss could be used for your roof design, but I suspect you will be using a truss.

Thanks, John! I see the term truss and rafter being used interchangeably in the web articles I've been reading. Whatever they are called, they are 4 boards, of equal length, cut at 22-1/2º angles and held together with gussets on both sides. ;-)

John F Dean wrote:There is a difference between a rafter and a truss.  Rafters are put in place during the build. The boards are heavier that those used for trusses.  Rafters normally allow for useable attic space.  A rafter supports the roof and is separate from the ceiling joists that support the ceiling. For example, the rafters on my cabin were 2x12s.  I enjoyed ample attic space.

Trusses are often built under climate controlled condition. The boards are smaller. The supporting members reduce useable attic space.  The roof and ceiling supports together as well as the connecting supports make up the truss.  For example, the trusses on my house are made up of 2x6s and 2x4s.  I have barely enough room to squeeze through the supports.

Either rafter or truss could be used for your roof design, but I suspect you will be using a truss.

Hi Bill,
What you are describing sounds like a truss. A truss is made ahead of time with lots of supports inside the triangle. As John mentioned, this allows the use of smaller pieces of wood, but sacrifices attic space. They are also generally faster to build with and do not require a ridge beam/pole.

Rafters do need a ridge beam/pole in order to be built. The attached picture is a simplified example of rafters vs truss. I got the picture from Flickr if there are any copyright people watching this.

Maybe this article from Mother Earth News will help:

https://www.motherearthnews.com/diy/how-to-build-a-gambrel-roof-zmaz77mazbon/

This article from Wikipedia has this image that might help:



https://en.wikipedia.org/wiki/Gambrel


Our first tiny house had that kind of roof.  Unfortunately, we had it built and only finished the interior so I can't help there.

Be sure to check your local building codes if any.