Timber Framers Guild

Why bother with tennons, and simply use metal?

Posted By: rlivesay

Why bother with tennons, and simply use metal? - 12/03/04 01:21 PM

I just completed a 4,000 square foot frame. My situation may be a bit different than most viewers at this site, in that I cut and milled my own oak and ash for the posts and beams, although I used pine for the floor joists. In setting up my posts, and laying the beams on top, which were 10X10 and 12X10 beams, on 12' and 14' centers, I chose not to use tennons/mortices, or at least not too many. There were a couple places that I used rudimentry tennons in attaching the garage and some other locations, but generally, beams were butt attached, and laid directly on posts with the second floor built from the platform on top of the ceiling for the first floor.

I started using tennons and mortices, but found it to be a HUGE investment of time, so bought the Simpson metal ties for the butt joints.

Basically, on top of all butt joints, I tied them together with two 3/64" thick X 1.5" wide metal ties, and about 7 galvanized nails per side of butt/per tie. In addition, I used 12" galvanized spikes down into the post, giving 2" penetration into the post, plus I used a thorough amount of construction adhesive on all joints.

Why is there such a fuss about tennons? Why won't this design work just as well?

My 45 degree supports also were a mixture: some with and without mortices. For those without mortices, I applied the same principle of using the Simpson ties to the exterior of the home, so they are concealed once the walls are in place. Why am I not as good off as the old fashioned folks using time consuming tennons?

Thanks,
Posted By: Mark Davidson

Re: Why bother with tennons, and simply use metal? - 12/03/04 01:46 PM

how well will the steel/glue and wood hang together over time?
how long will your building stand?
Posted By: gordmac

Re: Why bother with tennons, and simply use metal? - 12/03/04 04:31 PM

I love it...what a great question! Of course, it's a bit like walking into a nudist colony and asking why nobody's wearing a parka!

I can think of two obvious answers to your question: the first (and please don't take this the wrong way) is to quote the great explorer and Himalayan climber Bill Tillman when asked the obvious question 'why?'...he said simply "If one has to ask the question why, then one most likely wouldn't understand the answer."

The second answer is that we do what we do because we dig it; by carefully cutting and joining timbers in this centuries-old tradition we feel that we're creating buildings of integrity and lasting beauty...a legacy that we're proud to leave to our children and our children's children. A well-made, traditionally joined and pegged frame is an expression of craftsmanship in a way that cutting and nailing a Simpson tie or shooting an air-nail just...well, isn't. When a frame is nicely made (certainly not always the case) it's a celebration of wood that with a little care, should last for centuries. Most of the timber framers that I've met aspire to build beautiful things, and simply feel that the path of traditional joinery is a nicer one to follow than the path of nails and bolts. Our clients pay us to build this way because they share some of our aesthetic values, and because they enjoy the craft that they're supporting too; keeping a wealth of traditional skills alive, and participating in a tradition that quite literally spans millennia. I think most of us enjoy the spirit of a finished object more when it's been carefully and thoughtfully made. Not sure about this? Watch a group of people walk into a timber frame...and what's the first thing that they do? Inevitably they walk up to the nearest piece of timber they can reach and put their hands on it...big smile. Good enough for me.

Thanks for your question...it's good to remind myself what this is all about.
Posted By: Bob Smith

Re: Why bother with tennons, and simply use metal? - 12/04/04 02:28 AM

To borrow a phrase that is thankfully moving out of our national consciousness; "Mega Dittoes"
Posted By: gib

Re: Why bother with tennons, and simply use metal? - 12/06/04 03:06 AM

I'm a first-time timber-framer, and I feel no need to execute an English tie-joint or any other extravagant joinery that some mid-evil joe thought up. There are plenty of ways to carry out a structurally sound join, and the thought of a 6" timber screw or ½” re-bar join should not be automatically dismissed.

I plan to build a simple 10'x20' shelter using timber-frame designs, however I am going to do it myself and I plan to use whatever methods will save me a buck. This mode of operation should have high appeal to anybody who appreciates the beauty and timelessness of timber-frame construction. For a while, it was the only way to build. Maybe that time has come again.

Anyway, I will be using some mortise and tenons in my design, and my research tells me that it can't done in simpler fashion through some less involved procedure. But as regards residential design, I don't think that anyone will notice the circular holes of the pegs versus the small indentations of timber-screws. (Especially if it is contained inside a sealed wall.)

Just the two cents of someone who loves carpentry.

Regards, Tim
Posted By: Jim Rogers

Re: Why bother with tennons, and simply use metal? - 12/06/04 10:54 PM

This design discussion shouldn't be taking place in the "TOOL FORUM"...
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