Hi all,

I'm designing my first timberframe, and the client (my father) has two major requests: 1.) English-style gunstock posts, and 2.) overhangs at both the eave and gable. I've seen examples of this using common rafters, sprockets, or cantilevering the tie out past the plates. I'd like to use a principle rafter/common purlin system, and I was wondering if I couldn't just extend the rafters out past the ends of their ties. The purlins would also extend past the last rafter to form the gable overhang. Maybe something like this:


[img:left]https://plus.google.com/photos/102294554...CJ7IyYbb2-nVlQE[/img]

The building is rather small (18' x 22'), but it will be located in NH, where the snow loads can be heavy. Does this seem like a horrible idea? Any advice would be greatly appreciated. Thanks!

Dan

First thing that comes to my mind, would be to extend the tie out past the post. Lodge the purlins on top of the rafters, where they can cantilever the gable end rafters giving the overhang. The extended tie beam yields a square soffit box. Some thing to play with in sketchup. It is all simple to cut as well. The rafter you have drawn brings on some questions. I think I would just add a tacked on sprocket to the side of tie/rafter and stick to the straight on english tie as a second choice.

Hmm... I'm thinking sprockets might be a viable option, but my rafters are 6' on center. I'm thinking a sprocket every six feet would not be enough to support the eaves; is there a method for attaching sprockets between rafters? The overhang will only be about a foot.

Thanks for you quick response!

With the over hung ties you could insert a flying plate on the ends of the ties to carry the roofing.

Hi Dan;

You can also extend the rafter tails like this link shows, but the flying plate may be better:

http://www.forestryforum.com/gallery/albums/userpics/10095/JR-trussdetail1-s.jpg

Their is a type of joint in some historic work in Germany which uses a tie beam/rafter connection like a bridal joint, but I apparently do not have an image of this type or know the German name so I couldn't find one for you right now.

Jim

Jim,
That's a very interesting joint, and really close to what I was thinking of. I was inspired by this page out of "Historic American Timber Joinery"

https://plus.google.com/photos/102294554...CJ7IyYbb2-nVlQE

I'm thinking of doing a sort of a hybrid of the two, with the rafter morticing into the tie beam, but half its thickness passing over the end of the tie to form the rafter tail.