The Forestry Forum is sponsored in part by:

Forestry Forum
Sponsored by:

TimberKing Sawmills

Toll Free 1-800-582-0470

LogRite Tools

Forest Products Industry Insurance

Norwood Industries Inc.

Sawmill & Woodlot Magazine

Your source for Portable Sawmills, Edgers, Resaws, Sharpeners, Setters, Bandsaw Blades and Sawmill Parts

EZ Boardwalk Sawmills. More Saw For Less Money! sponsored by Northeast STIHL

Woodland Sawmills

Peterson Swingmills

 KASCO SharpTech WoodMaxx Blades


Sawmill Exchange

BRUTE FORCE Authorized Dealer

Woodshax Outdoor Vending Solutions


Council Tool

Baker Products



Author Topic: Joinery Question on Center Post: Mortise & Tenon  (Read 546 times)

0 Members and 1 Guest are viewing this topic.

Offline LimestoneWood

  • member
  • *
  • Posts: 6
  • I'm new!
    • Share Post
Joinery Question on Center Post: Mortise & Tenon
« on: July 13, 2017, 03:21:20 PM »
Hello Everyone,

My name is Andrew and I'm new to the forum.  I have been working on a timber frame design for an 18x18 shed.  I have run into a problem joining the tie beams to the center post.  The post is 8x8 and I would like to inset the 8x12 tie beam by 1 inch into the center post along with a 4" long 2" wide tenon.  But that sets the tenon 5" into an 8" post and I have to fit another tie beam into the same place on the other side.  Should I simply make the post 12" wide or should I go for an over-under tenon?  Or is there something else that I should do? 

Please remember that this is my very first timber frame and I am not looking into getting into very complicated joinery.  That is why I am using a post in the middle in the first place.  However, I am a woodworker by hobby so I'm not completely lost.   

Any help that you can offer is greatly appreciated.



Offline timberwrestler

  • Full Member x2
  • ***
  • Posts: 121
    • Share Post
Re: Joinery Question on Center Post: Mortise & Tenon
« Reply #1 on: July 13, 2017, 05:40:00 PM »
Widening the post could work.  A free tenon would be the modern answer to your dilemma.  It would run through the post, and go maybe 12-16" into each beam. 

The beam splitting the center post is more of a problem.  It's a hinge point.  You'll also have a lot of cross grain shrinkage.  Even without that middle beam, you should leave a gap between the rafters.  So that when the ridge beam shinks, they'll still bear on the beam.

Offline Don P

  • Senior Member x2
  • *****
  • Posts: 4313
  • Location: Southwestern VA
  • Gender: Male
    • Share Post
    • Calculator Index
Re: Joinery Question on Center Post: Mortise & Tenon
« Reply #2 on: July 13, 2017, 08:53:30 PM »
Lose the lengthwise center beam under the ridge, run the ties continuous and tennon posts under and over the ties, brace upper posts to ridgebeam?

Offline LimestoneWood

  • member
  • *
  • Posts: 6
  • I'm new!
    • Share Post
Re: Joinery Question on Center Post: Mortise & Tenon
« Reply #3 on: July 15, 2017, 07:21:02 AM »

Okay, so if I understand this correctly the center beam/plate should be removed.  I assume the posts underneath it would become taller and go all the way up to the very top plate/beam.  The tie beams meeting in the center post could then receive the floating tenons. 

I would still have nine posts but the center ones would be taller.  But now I would only have three beams/plates instead for four. 

As far as the rafters go, I don't understand the solution.  I understand wood shrinkage and now see the problem that has been posed but can't visualize how to fix it. 

Thanks for all your help!  I'll get a new design posted within the week to clarify the wording.

Thanks again,


Offline LimestoneWood

  • member
  • *
  • Posts: 6
  • I'm new!
    • Share Post
Re: Joinery Question on Center Post: Mortise & Tenon
« Reply #4 on: July 15, 2017, 07:24:51 AM »
Oh never mind on the rafters.  I get it now!  Duh:)

Share via delicious Share via digg Share via facebook Share via linkedin Share via pinterest Share via reddit Share via stumble Share via tumblr Share via twitter

Mortise/tenon question

Started by SwampDonkey on Timber Framing/Log construction

5 Replies
Last post November 24, 2011, 10:46:59 AM
by SwampDonkey
Preferred Mortise & Tenon

Started by Lurcherman on Timber Framing/Log construction

9 Replies
Last post July 26, 2008, 08:55:09 PM
by Lurcherman
Mortise and tenon width

Started by Believer on Timber Framing/Log construction

7 Replies
Last post April 28, 2012, 08:47:56 PM
by laffs
Anyone use commercial dovetail tenon/mortise jig

Started by ScottCC on Timber Framing/Log construction

0 Replies
Last post January 31, 2017, 05:16:57 PM
by ScottCC

Powered by EzPortal