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Worried about three way joinery. #5327 01/26/05 06:19 PM
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Mikeo Offline OP
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Hi
I have some concern about a joint where three beams converge on a post in the same plane. I've seen this joint executed before, and have accomplished the same results myself using through splines and timberlinx fasteners. However, I would like to try it with tennons and pegs only. The bents are pine, principal rafters w/purlins, queen posts,collar ties. My concern is where the tie beam and lower joists join the vertical 8x8 posts. Although I know there is little outward thrust from the rafters because of the queen post collar tie configuration I am nervous about it because of the way things are "supposed" to be pushing. the tie beams are 8x12 and the girts are 6x10 all supporting a second floor. Any thoughts on the cutting of this joint would be greatly appreciated. Thanks in advance
Mike

Re: Worried about three way joinery. #5328 01/26/05 07:02 PM
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Mikeo Offline OP
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Sorry, should have mentioned this a high posted cape so any outward thrust from the rafters would be on the 8x8 posts.

Re: Worried about three way joinery. #5329 01/26/05 08:18 PM
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Mikeo Offline OP
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Let's try that again. The posts are 8x10's with the tie beam tenon coming in on a 8 in side.
Sorry about that.
Mike

Re: Worried about three way joinery. #5330 01/27/05 02:01 AM
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Mark Davidson Offline
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why put a floor beam in that junction at all?
could carry the edge of the floor with 2x that could be fastened to the wall sheathing(the 2x could go into a shallow rebate on your post)? This would make your primary tie joints stronger....

Re: Worried about three way joinery. #5331 01/27/05 02:56 PM
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Mikeo Offline OP
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A 2x would'nt be strong enough to carry the load. There will be 6x6 floor joists running parallel to the tie beam (from the wall girt to a summer beam), so the tops of all those members are in the same plane. I guess what I'm asking is- if I go with a 2in through,half dovetailed tenon on the tie beam, that leaves only 3in on each side for tenons for the wall girts. Not much relish left after pegging on those tenons even if they are not in tension. Is this common practice?

Re: Worried about three way joinery. #5332 01/27/05 05:52 PM
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Mark Davidson Offline
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ok, i thought you had common joists running perpendicular to the tie beam.....
the timberlinx would be stronger, in my opinion, I'm not crazy about a three way join at this spot in this frame(neither are you, if I read your post correctly), I would think you do need good strength above the tie beam connection for high wind loads and for raising the frame...would it be possible to move the floor beam in from the wall a bit(at least 6" from the inside face of the post)?? There are probably several solutions...

Re: Worried about three way joinery. #5333 01/28/05 01:57 PM
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Mikeo Offline OP
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I built my shop the same way( using timberlinx and splines) and it looks really nice. My client likes the way it looks and wants to do the same. His thing is he would like to eliminate any metal fasteners. Go figure. Happy customers, you know. I will probably end up doing the same thing again. I know its' workable and strong. Just always looking for another way to do things.
Mike

Re: Worried about three way joinery. #5334 02/04/05 02:37 PM
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Tony T Offline
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Are the posts already cut? If not why not use bigger posts and/or gunstock post?

Re: Worried about three way joinery. #5335 02/08/05 12:21 AM
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Mikeo Offline OP
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Yes, that would have been an option, but the posts are already sitting in the yard.

Re: Worried about three way joinery. #5336 02/09/05 03:21 AM
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piller Offline
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OK, customer wants a traditional crafted frame with no modern metal fasteners, sounds good. You have 8x10 posts, with 8X12 tie beams and 6X10 girts coming in for a three way connection at the post. You want to use a through half dovetail joint on the tie beam, nice.

So, what to do about the girt to post joinery?

Will the 6X10 girts be flush with the outside of the posts (where will the girt be located on the 10" wide post)? Will you have braces for the girts? How do you plan to house the girts? How long are the girts, how many 6X6 joists will there be on the girt, what are the loads on the girt? Do the tops of the 6X6 joists need to be flush with the top of the girt, what joinery is planned here? How about the summer beam joinery to the tie beam? What are the details of the tie beam through half dovetail joint, how much material will be removed from the post?

I would be very reluctant to proceed with a three way joint as suggested, without further information.

Your options are to consider locating the girt to post joinery either above or below the tie beam joinery, or to take advantage of the sheathing as suggested by Mark. However, it sounds like the customer would object to using the sheathing.

So, one option is to locate the girt to post joinery above the tie beam joinery. Probably not a practical approach, it would require several changes, but it might be possible.

Second option is to keep the girt/post/tie/summer/joist design as is but indirectly connect the girt to the post with support framing below the girt. I've seen this accomplished in two different ways.

One method is with a horizontal member below the girt that connects to the post (spline joinery or pegged mortise/tenon) and supports the girt. The horizontal support member can be connected to the girt in a variety of ways, I saw a nice design where the member was keyed to the girt using nicely contrasting wood, similar to what one might see in a scarf joint. This member can be a full length beam or kept short and braced.

The other method is to use a vertical member that attaches to the side of the post, the girt is supported by and attached to the vertical member. The bottom of the vertical member is supported by a sloped shoulder housing in the side of the post, and the vertical member is kept attached to the post using a through free tenon/spline that is wedged/pegged.

--Chip


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