Garden Shed from ash timbers

[DanMc]

My wife has been bugging me for a long time to build her a garden shed.  I have an HM126 saw mill and ended up with enough logs to produce all the wood I need for the build, so I made a rule that all wood for the project must come off the mill.

This is a 9'x12' footprint with a 12 pitch roof.  

Generally, it's my understanding that a timber frame is typically built from spruce or some other softwood, but older barns like the one on our farm was built out of a very tight grained hardwood - maybe maple.  In my case, all I have to work with is white ash and a couple big red oak logs.  Most of the milling is completed.  Considering that shovel handles are made from ash, I would expect that this would be strong.  

I have no prior experience with a timber frame build, so my natural inclination is to make some easy-to-cut notches and tie it all together with Timberlock screws in deep pre-drilled holes.  This is the point where I was thinking I might get run off the forum for violating the purity of the timber framing culture.  Cutting 20-30 square mortises in hard white ash timbers is a bit of an undaunting task for me.  Feedback from you experts will be helpful in this area.

Anyway, I have a design that I've been working up in SketchUp.  Here's a screen grab to get started with.  

[WV Sawmiller]

Dan,

  I saw your concern about comments from some of the experts here, of which I am not one. As I read your post right now it is just for information. 

   If you have a specific question about some aspect of the build I'd suggest you post  that and see if you don't get answers to them. Good luck and be careful. Be sure to include in progress photos/reports.

[Jim_Rogers]

Joining timbers with timberlok screws could work if there is enough support for the timber. Such as a shallow notch/housing as mentioned. However, with the ridge beam and center supporting post coming down to the tie beam, there is a lot of loads there.
There will need to be good support for that.
When a tie beam joins the post, the area supporting the tie is the length and width of the through tenon as well as the housing area. Meaning many square inches of side grain as well as end grain in the mortise.
Just the housing and a few timberloks may not be enough support.
You'll need to figure the loads and support capacity of the screws in that joint. 

It is great to use what you have but you'll need to make sure it is all safe for everyone. And that means after you and your wife have left the property.
Jim Rogers
Good luck with your project.

[DanMc]

Thanks Jim, and WV for your feedback.  

I have looked at a few other timber frame designs and it seems common that they don't use any ridge beam.  I don't understand that, because then the rafter beams would want to spread out the walls unless low collar ties are added.  So I added the ridge beam and the support posts to keep that from happening. 

I did a little more digging into timberlock screws and found that they're generally used for landscaping timbers and not for a structural applications.  My initial thinking of timberlock screws stems from a friend who built a larger structure, and he reported that he used them.  Just because somebody else does it, doesn't mean it's a good thing.  Now I'm shying away from widespread use of these in load-bearing locations.

I currently have a 3/4" notch in the corner posts for the tie beams.  Maybe I should double that notch to 1 1/2".  That means there will be 7 1/2 sq inches for the supporting surface.

This morning I came across "barrel bolts", here: Barrel Bolts - Timber Frame HQ

These look great, but the nuts are crazy expensive at $16 each.  I could machine barrel nuts out of 1" round stock for 1/2" threaded rod fairly easily.   

[Don P]

Timberlocks are a structural screw, I've used quite a few in construction.
This is the building code engineering services report with allowable design values for their various fasteners;
ESR-1078 - OMG, Inc. (fastenmaster.com)

It looks like you need to figure out better support for the tie beam that holds up the ridge support post. It looks like there is room to simply bolt a shorter jack post to the corner post for that tie to sit on. You'll need to size the tie appropriately for the large midpsan point load.

I had some pine tops at the end of the day today and was experimenting with what the swing blade could do. The left hand is a 8x8 corner post guttered (that corner notch) to  6x to form an interior corner, that is fairly typical on turn of the century houses. The right one is a 6x8 midwall post. I set it up to slide horizontal shiplapped rough sawn boards in the grooves. I might tarpaper over that and install Board and batten if it needs to be tighter.

[Chilterns]

This looks interesting !

Can you post a pic of your "swing blade" and a sketch showing how you intend to use these posts please.

[DanMc]

Do you run the blade through at varying depths to get the wide slot?

[Don P]

This is a swingblade mill. The 24" flush faced blade, on this one, can pivot vertical or horizontal. It rides rails that have vertical adjustment, end to end is independent it can taper. There is a horizontal bridge to track the blade left or right, and it can swing vertical or horizontal. We made a swingset at the end so we can lift and spin the whole carriage around and attack the other side of the timber as well as double the 6" maximum vertical and horizontal cut this model can do. Here we needed to skim the tops of log rafters. They were longer than the rails so we levelled roller tables. Roll forward and go again.




This is one of the corner posts underway.


 
I've flipped it 180 and down onto its opening top face. I could saw the 8" wide but only 6" deep. So I did that and flipped the cant onto a levelled surface, removed the top of the cant down to 8". Dropped the saw and removed the overhanging chunk of wane that was on the left, just like the remaining one on the right. I'm working the 2x2 notch out of the corner here. (you can see the saw intersects at the "point" of the cut when it swings) I've walked backwards pulling the saw in vertical position, once clear at this end I've swung it horizontal and am pushing it through the horizontal cut. That wasted out the corner. I then cranked the rails up 1/2" rolled the sawhead right and began vertical rips to make the board groove. I can make the one in the left side by swinging the blade horizontal and ripping, raising the rails 1/8" and repeat. Too tedious, I roll the cant 90 line up and do it with the horizontal adjustment as well. That only took one  :D.

What I was hoping to show there was not the mill but the profile of the posts. My mill is a regular circle mill so I'm used to just being able to do squares. I've done all that grooving on the job with skillsaws and routers before, I just had the swing mill here this time.

Which, was all a very long winded way of saying, you could cut grooves in the posts to slide siding or sheathing boards into.

Oh, while you are in the aisle with the timberlocks, you'll see ledgerlocks, much less length selection but that is a stouter screw. Designed to attach a deck ledger to a floor rim.

[Don P]

I think I stole Dan's post  :-[

Here's the shed that's in my mind at the moment;