12x16 pavillion - 6"or 8" posts?

[Mike KY]

Hi, I'm planning on building a 12x16 open air post and beam pavilion with a gable roof. It's going to have 6 posts, three supporting each 16' beam, with tie beams connecting the two post/beam assemblies. I'm using metal brackets but have been looking at similar timber frame buildings for design ideas. Just about all timber buildings of similar size and design use at least 8" posts. I feel like that is way overbuilding, there is little snow load here in central KY. I then realized maybe 8" timbers are used to allow the traditional joinery to be strong enough. If I'm using metal brackets for fasteners can I get away with 6" posts and maybe 6x8 beams? I want to use black locust for the posts because of it's decay resistance but can't find 8x8's, only 6x6's.

Thanks!

[poppy]

Mike, 4x4's would work structurally, but large posts are used for looks as much as anything else.

I would think that 6x6's would look pretty good considering the size of the project.

[Don_P]

I agree with Poppy. I logged and processed a stand that contained alot of black locust this spring. I got 6x6's and 6x8's out of it. i think there were 2 8x8's and 2 10x10's, the bigger trees are almost always punky inside. I plan on timberframing them a small barn at some point with the timbers. Standard rule of thumb is to make the joinery 1/4 the nominal size of the timber, so for 6x the mortises and tennons are 1-1/2" wide. You won't have any trouble with strength in that dimension at that size, locust is the real thing. You will need to pilot big, I've had to run 5/16" for 3/8 lags and full diameter for the shank to avoid snapping them.

[Pine Cone]

This 16'x16' one was built with 6"x6" posts and it seems to work fine.  You could use 8x8s but I can't imagine you would need the extra strenght.

[Mike KY]

Thanks for the advice everyone. I'm going to use 6x6's. Another thing I've been wondering about is whether to mix woods in the framing. For some reason it makes sense to me to use locust for the posts and beams and use something cheaper and easier to fasten, like pine for the roof framing. Do folks often mix woods like that in a frame?

[Mike KY]

Oh, and that a great looking building pine cone, I'm thinking of a pretty similar design. What is your roof pitch?

[poppy]

I agree that locust makes for good posts and I'm certainly in the camp that encourages the use of multiple species of wood.

I base my timber selection on what's available.  In the house rehab project I'm using maple and red oak timbers.  In my timber frame cabin build I have mostly red oak, but also white oak, maple, and cedar.

I'm actually trying to use as many varieties as possible in the cabin for subfloor, finish floor, accents, and miscellaneous projects.  So far I have black walnut, pin oak, pine, sassafras, cherry, poplar, teak, hickory, and some 100 yr. old timbers that are not identified.

[Pine Cone]

My roof pitch is 6 in 12.

Mixing wood shouldn't cause any problems.

[John Raabe]

Very nice job there Pine Cone. I especially like the way you have tied all the bracing and trusses together with standard framing members.

[Sobaki]

Pine Cone, I know it's been a number of years since this thread has been posted in, and if need be I will attempt to get in touch with you through a new thread, but I was wondering if you had more pictures of your pavilion.

I'm currently going through the planning stage and when I came across the picture you provided above, I knew immediately that is the sort of pavilion I want in my backyard.

Any information you could provide would be greatly appreciated.

Thanks.

[Pine Cone]

I just happen to have one or two pictures in the archive...

Here are some pictures.  It was pretty much a seat-of-the-pants build, no engineer or architect, no guarantees it will work for you...

Router jig for making knee brace tennons


Knee braces cut and ready to go


Test fit of knee brace tenons into 6x6 main beams.  Note rabit cuts in both directions the depth for 2x
















Metal roofing installed directly on top of purlins
















Lots more pictures of the whole project can be found here...
http://countryplans.com/smf/index.php?topic=8030.0