Tim and Will,

Looking outside my window as I write this, I see farmland surrounded by forest that is primarily a mix of beech, birch, maple and hemlock - not too dissimilar to much of Vermont. From the healthy maples, I produce sugar. The unhealthy maples give me warmth. (It was 18 below zero this morning.) Given the choice between the scattering of beech and large stands of hemlock, for better or worse, I choose hemlock.

Dovetails? Well, I'm an admitted rookie at timber framing (though an experienced woodworker) who's still trying to sort out the best practices. I ended up choosing to dovetail the floor joists because this building will only be sided on three sides (board and batten). Knowing that it will not be stiffened by a continuous skin, my thinking was that I'd take advantage of any opportunity to tie frame members together with the hope that every tied connection would improve the overall integrity of the structure.



I've done the same for this building. I haven't put wall girts at the post/tie intersection. The joists are only in the ties. My braces have a rise/run of 3.5 feet between the post and the top plate.

Thanks so much for all the feedback. I've learned a lot from the input and the rethinking it leads to.

tim -

a 2' kneewall is perfectly workable if you have a structural ridge, principle purlins, or other such arrangement to keep the roof from spreading.

the op's design has 10' of roof being spread to the plates, with 10' bays, and something akin to a principle purlin / saltbox type design - so it shouldn't be a big deal. not how i would have done things - but then again - my first frame (a porch in white oak) had plenty of 'book learned' things in it that i wouldn't do again...

Hey Mike,

You put it so kindly

Yup, I'm pretty much self-taught in everything I do. I read books, ask questions of those with experience (such as the broad range of skilled practitioners represented in this forum), refine my own techniques, repeat.

I don't have any aspirations to make my living from timber framing, but I do have a need for a few structures on this hillside farm and one will, I'm sure, see the progression of my learning as those projects evolve.

Thanks again for your feedback.

Hi Mike, I think we chased this tail around a few months ago. I am in 100% agreement when additional paths are taken, as Ken often says. It is when no other additional structure is involved, which concerns my previous statement.

I should also clarify my hemlock aversion. The hemlock which grows around here is full of shakes. When I do use it, and that is not often, I am careful where it goes. A new framer should be on the look out for shaky hemlock.

That said, when working on my own frames I will use a lot of wild stuff, pushing the limits for sure. I am now scraping along my blueberry field edges for rafter stock, I am finding balsam fir to be another discouraging species due to the rot content, but I am using it all the same, and making some poor fire wood to boot.

Tim

Will T and Timbeal, have you guys ever heard someone describe what you all propose as "galloping" joists? Think that sounds cool.

Tim,

The hemlock in my forest is relatively young and shake free, for the most part. I agree that it can be a problem if one does not keep an eye open for that downside. Otherwise, hemlock has been commonly used in these parts and seems to be wearing well in the old frames I've seen built with it.

Tim – Where did I lose you? I was trying to be both descriptive and vague at the same time, to plant some seeds and provoke thought.

Kevin - I had nothing to add to this conversation until you asked out loud if there had been an awakening like change of opinion regarding drop-in dovetails since the books you've been reading had gone to print. Yes there has, most framers avoid them and have for some while now.

You did make it clear that you were a newbie, which is why I threw in a bit about the kneewall and my unabashed opinion of Hemlock. There's plenty of it right outside my window also, and I consider myself part my local forest economy, I buy local almost with out exception. It is not just Hemlocks propensity for ring shake that has me dismiss it as a framing timber (or that that often doesn't rear its ugly head until a timber is laid out and joinery is being cut) but that it's gnarly grain makes it hard, unpleasant and time consuming to work. It's a wonderful first layer for a two layer barn floor, makes good skip sheathing on a roof, there's a mill up the way that dresses it up into handsome, durable and nicely priced strip flooring. I do buy it, I just don't frame with it.

Old growth, dense ring count wood, is night and day in many species, this one especially

Mo – I know of no other name and I like the one you just coined, good stuff !

Will, right here along these lines...

" you will spread the moment over more square inches of joinery/timber and shift the bending moment up, and effectively shorten the kneewall. It would at the same time provide ready and full access to the dovetail tenons wedge"

Moment spread around? At first I thought you may have been alluding to the wedge on the tie to post connection, but that is covered by the boarding. So how are the theoretical dovetail wedges still accessible?

Spruce, what do you think of that for a workable wood? And I am loaded with it. I don't have a choice at times, gnarly, snarly spruce it is.

Galloping joist? Can that now be found in the wiki pages?

Tim

Okay, so there's been some weigh-in about whether the dovetail is even a joint that should be used in floor joists. Just so I'm clear, what do you see as the primary reason why the dovetail has fallen out of favor with contemporary framers? Is it a structural concern or an economic concern?

for me, both.
lots of labor to cut, and you remove lots of wood...

if you need to pin the joists together - i'm a fan of the tusk tenon and stepped or tapered housing (assuming you can get a tenon on the NA of the carry beam)

or drop ins with lag, panel screw, spikes or nothing, again - depending on the application.


for production shops - i'm sure there are ways to jig up the dovetails for hand work (routers, etc.) - and i've seen a fancy tool head for a hundegger that will do a dovetail like housing that you can automate and cut that allows a tapered dovetail end to be tapped in from the top... but i've only actually seen it in use once, for a tool shed roof.



as noted - in green material they will shrink across the grain and the carry beam will not shrink noticeably along its length - so you are putting plenty of work into something that will be ineffective for its intended design pretty quickly as the material starts to dry. not to mention all the material you are taking out of the compressive face of the timber, replacing it with something that may go in tight, but never be as sound as leaving the material in the first place.

my $.02, which isn't worth much in this economy...