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#33571 - 03/04/16 06:48 PM First timer
Jar Offline
Member

Registered: 12/14/14
Posts: 5
Loc: Maine
Hello to all,I'm new to this forum and about to attempt my first timber frame.I am finding that the planning seems to be about two thirds of the labor in designing and building my small barn. The barn will be 16'x36'. I am using Eastern White Pine for my frame.Posts will be 8"x8" and crossbeams are 8"x12". Will be cutting shouldered thru mortise and tenons in the post to accept the crossbeams,w/2" thick tenons,the crossbeam will be housed 11". I'm not sure how tall to make the tenons ? Should they be the full 11" tall or will I be removing to much material from the post ? Is there some kind of standard based on the height of the timber ? I guess I should say the crossbeams will be laid out one foot down from the tops of the posts. Thanks in advance. JAR

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#33572 - 03/04/16 07:13 PM Re: First timer [Re: Jar]
Dave Shepard Offline
Member

Registered: 02/19/06
Posts: 707
Loc: Alford, MA
If you are using 1" reductions, then an 8"x12" tie beam would have an 11" deep tenon.
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#33574 - 03/04/16 11:16 PM Re: First timer [Re: Jar]
Jim Rogers Offline

Member

Registered: 03/14/02
Posts: 1607
Loc: Georgetown, MA, USA
We normally reduce the height of a tenon by 1/2". If it his housed into the timber 1" that will make a nice support shelf for the tie beam.
Housing into a post and reductions on a tie beam are two different things.
We normally establish some "frame rule" one of which is the reduction amount.

Keep asking questions and good luck with your project.

Jim Rogers
_________________________
Whatever you do, have fun doing it!

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#33575 - 03/05/16 06:12 AM Re: First timer [Re: Jar]
Jar Offline
Member

Registered: 12/14/14
Posts: 5
Loc: Maine
Thanks to you both.I will be housing into the post 1". Was trying to figure out if there was some kind of standard/traditional frame rule on tenon size based on the timber dimension ? Also is it really nessasary to make that tenon 11" tall ? As I understand it these joints are mostly under tension,I will be double draw pegging.Just wanted to make sure I am not removing to much material and weakening the posts.I have been helping a friend felling/milling all the pine here at my property we're about to the halfway point to filling the list.It's been a great project so far. I can't wait to start cutting joints but am finding that good planing and patience seems to be key to doing a project like this ! Thanks be that I have a lot of patience and a brother with a CAD program who will certainly not be bashful in letting me know of any errors in my drawings. Great site,I have been all over it the past year or so getting all kinds of info. Gotta go cut down some trees now !!! Thanks again.

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#33577 - 03/05/16 09:15 AM Re: First timer [Re: Jar]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1875
Loc: Maine
Just to clarify, the theoretical 1" is just a theory. It will be pulled from the outside of the post and end up being more correctly measured as 7" from the reference face on your 8x8.

I don't see the 11" deep/long through mortice in the post being helped by making it shorter, you have already severed the fibers in the post, even if it was just a 2"x2", that may be a stretch but is shows the point.

Then there is the whole picture, span of building, roof pitch snow loads, species, peg size, spacing distance from shoulder, what day of the week, moon phases, etc. that can weigh in on this. That is what engineers do.

Where in Maine are you?

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#33578 - 03/05/16 09:27 AM Re: First timer [Re: Jar]
Will B Offline

Member

Registered: 10/02/02
Posts: 177
Loc: Massachusetts
Jar,
As Tim says, you've already done the damage with the mortise and making it longer doesn't have much effect. Also, making the tenon narrower is actually more work, since you will cut the shoulders first with the tenon full width and then cut it narrower if you need to. The only time you need to is to provide some relish if the mating mortise is at the end of its timber, or if you have an opposing tenon coming in that needs clearance. Thus, the rule of thumb is that tenons are the full width of the timber unless there's a good reason to do otherwise.
_________________________
Will
www.heartwoodschool.com

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#33580 - 03/05/16 12:01 PM Re: First timer [Re: Jar]
Jar Offline
Member

Registered: 12/14/14
Posts: 5
Loc: Maine
Thanks to both Tim and Will.I appreciate your input and now I'm feeling better about tenon sizing.I do agree with you Will,about full width being easier to cut. That's what I'll be doing in this case. Just so you guys know I'm not the fly by the seat of your pants type of guy.Even though I don't consider myself a carpenter I do have a lot of experience in building of all aspects of residential homes.My brother is a contractor down in Sudbury Ma. area and also a very meticulous Master carpenter [some would say anal ] He's got an associate builder/engineer looking at my plans to make sure I am doing things right. Therefore floor loading,snow loading and all that voodoo I don't know about. At no cost to me,I like that part !!! To answer your question Tim, I'm in The Sebago Lakes Region of Maine.Thanks to all of you once again. JAR

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#33581 - 03/05/16 05:36 PM Re: First timer [Re: Jar]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1875
Loc: Maine
Southern Maine, nice pine down that way. Looks like you got things covered.

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#33582 - 03/05/16 11:48 PM Re: First timer [Re: Jar]
Jim Rogers Offline

Member

Registered: 03/14/02
Posts: 1607
Loc: Georgetown, MA, USA


Above is an example of a tie beam to post connection.

There are some standard rules about joint sizing. For example the tenon thickness is 1/4 the beam width. So if you have an 8x8 then the tenon is 2" or 1/4 of 8". If you have an 8x12, the tenon is still 2" as it is 1/4 the thickness.
The peg size is then 1/2 the tenon thickness, so it would be a 1" peg.
For a smaller frame such as a 6x6 beam then the tenon is 1 1/2" and the peg is 3/4".
The next standard is the reduction. The reduction is the amount that the 8x8 is reduced to a standard size so that the joints will fit together.
We normally do 1/2" under the requested size. So if it is an 8x8 the end is reduced to 7 1/2" in height. If it was a 8x12 then 11 1/2". The mortise and housing would then be 11 1/2" as well so that the timbers will easily fit together.

If you're interested in seeing all this type of layout and joinery come to the Old House and Barn expo next weekend in Manchester NH on Saturday the 12th and Sunday the 13th.
The guild will be cutting joints and erecting an 8' x 12' garden shed/kid's playhouse frame using all of these standards.
Here is a link to that event:

Check this out.

http://www.oldhouseandbarnexpo.org/old-house-and-barn-expo/


Jim Rogers
_________________________
Whatever you do, have fun doing it!

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#33583 - 03/06/16 09:40 AM Re: First timer [Re: Jar]
Jar Offline
Member

Registered: 12/14/14
Posts: 5
Loc: Maine
Ya I have quite a lot of good useable pine,some too large for the woodmizer.I may have to break out the old Sperber Mill but will have to make some new slabing rails. I'm thinking I got this under control,but still going over all plans w/fine tooth comb.Happy to have two others going over my plans. I don't like surprises.I have done some small TF projects,just some basic joinery and was very happy with the results.So I'm confident in my ability to get this done properly.


I have had Jack Sobon and Rodger Schroeder's Timber Frame Construction book,I think for over 20 years now (scary) amongst others as well. And have been collecting and gathering tools for even longer. I have two boring machines,one is a Swan that I picked up 25 years ago for $75.00 and get this,I was on a job last year in Portland working on a house that had a fire,looking thru the pile of junk that was going in the dumpster,saw a crank handle sticking out and knew rite away what it was. So I now have a working cond Millers Falls also.

Thanks Jim for all the input you have all been helpful and it's greatly appreciated.

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