16x24 Guest cabin build with black locust and maybe walnut?

[Yoter]

My property is LOADED with black locust.  I have six black locusts next to my barn that will probably come down by the end of this year because they are too close and I already had one come down and clip the back corner of the barn, but luckily I was able to stabilize it with some new timber.  The trees range from 50-60' in height and 24-30" in diameter at the base.  The plan is to have a pro come in and drop them with a crane, keeping the main trunks in 12' sections.  The branches and tops alone will give me all the firewood I'll ever need.  I've also got a fair amount of walnut that could come down as well.  I believe its white walnut or butternut, not the highly desirable black walnut.  I had one fall last spring and had some milled up for a friend by a buddy that owns a WoodMizer:



 



 

In any event, I have been planning on building a small guest cabin on my property for a while and I'm thinking of using as much lumber from my property as I can in the construction.  


 


My buddy with the mill has milled locust for me in the past to make 6x6 posts which I used to build a woodshed.  I don't know that I'm ready to tackle a full post frame build, but what I may do is stick frame the walls and sheathe them with locust boards.  I'd like to build actual post frame trusses from 6x8 locust timbers.  If I have enough walnut I was thinking that I would have it sawn 1" or 5/4 thick to use for flooring.  My buddy charges $125 a day to have the mill onsite and $0.65 per board foot milled after that.  That seems to still put me way ahead of store-bought lumber pricing.  I have a fair amount of stick built construction experience having worked construction all through college and for a time afterward, plus owning an old farm property and having built/re-built barns, chicken coops and other outbuildings.  I'd be interested in some feedback/advice on this potential project.  Mostly I'm wondering about working the wood green vs. dried.  Should it be dried first or put up green?  Also, I'm well aware of how hard locust is and will plan to use screws/timber locks for all connections.  Looking forward to hearing from others with more experience here.  

[Don P]

You'll very rarely cuss a twisted board if they were dried first, the twisted one goes to the woodstove instead of up on the wall. 

Where the wood handbook says a prebore for a connection can be 70-90% of screw root diameter, that 90% is there for woods like locust, hickory, beech. I've bent and broken a lot of fasteners in locust, burned blades and culled lots but it is high on my list of good woods. It makes a beautiful floor.

[firefighter ontheside]

Your picture looks like black walnut and not butternut.  Butternut is rare and I'd be surprised if you have a lot of it.

[Dave Shepard]

I don't like working locust. You can figure double the time for joinery over white pine. Then add in more time to replace the parts that curled up into a ball and rolled down the driveway. This sill has bowed more than 3", and is starting to get shake in it.



 

The other sills, as well as it's replacement, are doing ok, so far.



 

[Brad_bb]

Timber frame uses mortise and tenon and wood pegs(traditional)
Post and beam uses steel plates and bolts.
Sounds like you're talking about doing a hybrid using timberlinx fasteners?

It's a common misconception that one method is faster or easier or cheaper than the other, but it's generally accepted that this is not true.  The truth is, all of these methods rely on very careful layout and fitting.  Since that is the case, why not Timber Frame?  You don't have to rely on anyone else for parts.  You could hire an itinerant framer to help you do the layout/marking and teach you to cut joinery in an efficient way. I know Timber Framing is intimidating for beginners.  There's a lot of mystery is how everything is fit so exact and tight.  You'll find out it's not all that hard and follows a logical method.

You can certainly use green timbers for timber framing, that's what was traditionally done.  With metal fasteners, I'd be considering the chemical interaction of the metal with moist wood and corrosion and wood staining.  Now if you have time to let your timbers air dry for a couple years, they won't totally dry but will get a lot of their movement done BEFORE you layout and cut your joinery.  I think it's better this way.  Many times joinery is cut, but if there's an extended period of time before it's assembled/raised, you may have to do some modifying/refitting of some pieces.  If you don't have time to air dry for a couple or more years, then i'd prefer to assemble quickly after cutting joinery(within a couple months).

Walnut does work well.  Keep in mind that you can use branches and smaller upper trunk pieces for brace stock.  I mill a lot of live edge braces, that get square ruled into the frames.  You can prefit the braces and trace the live edge shape on the post and tie or plate and router your housings so they fit tight and are a beautiful joint and timber in the frame.

I've never had Black locust so I can't comment on that.  I do use Osage though, which is very dense.
I wouldn't be scared to use these woods though.  So a joint take a little more time, you don't have that many joints in that sized frame.  You can also grab a power tool if you need too -planer, saw, disc carver   You'll see once you learn the right way and cut a couple joints.

Oh, and if I were you, I'd use 8x8 material, it just feels better in the room.  For your tie beams, you may need 8x10.  I suggest you work out the design before you start milling.  When I say 8x8 material, I mean full dimension, not 7.5x7.5.  The two have a totally different feel.  You'd think that 1/2" wouldn't make much difference, but visually it does.  When I cut timbers that I'm going to dry for 2+years, I cut walnut 8.5x8.5.  I have a beam planer that I later square up the timbers with down to 8x8.  A walnut 8x8 or 8.5x8.5 will shrink about 1/4" in each direction as it dries.  Osage will not shrink that much.  I will cut osage to actual size. I cannot plane later when it's much drier with my straight knife beam planer.  It will tear out too much.  I've heard that helical planers can plane it.  Since I don't have that capacity, I cut osage to actual size that belt sand it smooth. Not sure about Black Locust shrinkage.

[kantuckid]

OP-location? 

Butternut is more common north of me and now days uncommon in KY. I would not call it less desirable if it has quality logs, but not for coinstruction-cabinet wood only IMO. Much has died from disease. The nuts are tasty but I personally like blk walnut, pecans or hickory nuts best. Blk walnut was a common construction wood back when they used what they had for whatever.  Locust  I have none big enough to saw-wish I did. 

[Magicman]

My buddy charges $125 a day to have the mill onsite and $0.65 per board foot milled after that.

 I could also be your 'buddy' with those rates.  ;D

[Don P]

If it was a day of my typical black locust you would earn it  

I used our jobsite terminology above which is kind of loose, and then I saw several people liked it, I reread to see why and groaned at my semantics in such erudite company. After lots of lags and screws I know this part of the wood handbook pretty well, so I figured I'd write a book report. These are the parts of a prebore that I do in something dense like black locust for a lag bolt.


 
For a 3/8" lag in good locust I'm usually breaking them until I have a 5/16" pilot. In a white pine to white pine joint up to a 3/8" lag does not need a pilot in that lower density wood. In kit log building before the modern log screws we used lags. In EWP and WRC we would just prebore and counterbore. By using 3/8 lags we could skip the step of drilling with a pilot. I do have a prebore with an adjustable counterbore on it for that. A pilot was another drill with a long skinny bit. From 3/8 up a pilot is needed no matter the density, the larger screws split more wood than they grab if you don't do a pilot. In dense woods with 3/8 and down lag screws you usually wring them off before they strip. A pilot is not required but due to the density it is necessary.  From 1/2" up the lags usually strip first but at ever higher loads depending on density, diameter and depth of penetration.

That is old school 40,000psi tensile steel lags. The newer fastenmaster, etc screws have their own individual specs, usually hi tensile 100ksi steel. No pilot or prebore needed, often no counterbore.  They are smaller diameter, You get hi strength, penetration but not diameter, but you won't wring these off in that steel, stripping in the wood is the usual installation failure. Until you get to black locust, there I prebore through the attached member with 1/4" clearance hole and to within 3" of the tip of the screw (the threaded length). The ledgerloks and loghogs are brand names for thicker, stronger, larger diameter modern screws.