Advice for my shed- from the ground up. Ties and plates

[ckprivette]

Hey y'all.

I'm hoping to start working on my shed in July or August. (Maybe I'll have all the details sorted out by then.) I've learned from Jim that 8"x8" black locust posts will suffice for this shed. (see attached skp file.) So the next timbers I have questions about are the ties and plates. I'm planning to use poplar for these, and I need some help determining proper dimensions. How big do you think they should be? I'm also looking for joint advice (carving, not rolling  :D): What size should I make the mortises and tenons in the ties and posts, and what type of scarf joint should I use, and where should the scarf joint be in relation to the posts? Is one scarf joint per plate enough, or should I plan on two? Thanks much!

chris
FYI, the side shed shown in the skp will run the length of the shed, and there will be one on both sides.
My thanks to Piston for the sketchup file.

[razor]

Nice looking shed. I would feel comfortable with 8x8's everywhere. There are no big spans to worry about. And the building is only 12' wide.
One scarf in the 36' plate is all you need. Lay it out so the scarf is over a brace pocket.
2" wide tenons set in 2" from reference face, 4" deep. Except for the thru tenons in the tie beam which are wedged I see.
Just a thought here but if you're milling your own poplar, consider sawing full length plates if you can. It is a lot of work but worth it when you only need a couple and doable if you have a bandmill. I've sawn 40'ers on my 21' WM.
Looks like a fun project.

[Jim_Rogers]

In order to determine the size of the plates we need to understand the timber values. The NDS does not show Poplar in the list of types of woods. So I can't look them up and use the online calculator to size the timbers.
We need to understand the exact type of poplar you're talking about using.
Then we can see if someone can provide these values so we can use the calculator to size the timbers.

On the tie beams, those sizes will be determined by the load being put on them. Are you going to have a loft in each bay?
What are you going to store up there? We need to figure the load per square foot on the loft joists and or tie beams, in order to size them.

As mentioned the frame is drawn with a 2" x 2" layout. Normal timber framing standards says that the tenon and it's mating mortise is 1/4 the beam thickness. You have 8x8 posts so that means a 2" tenon and mortise. Usually that means they are held in place with a 1" peg.
Next you need to add to this "general frame rule" a rule about the reduction or housing. Normally we do 1/2" under so that it is easy to cut and works to a standard dimension.
After that you have to decide on which face of an interior bent the joints will be cut flush to. So that all joints in all interior bents line up and are easy to layout and cut.

If you know which side of the structure is north then we can put a north arrow on the plans and use that to determine the name of the face of the bent that has all the joints flush.

As an example: All bents are laid out from the north, except the southern most bent.

If you don't know for sure which way the frame will sit on/at the site then we can just pick one gable end and say that they (the interior bents) will all be flush to that side. But you need to determine this so that you can pull all your dimensions from that end.
You can use the reference faces on the frame design if you wish.

Jim Rogers

[ckprivette]

Thanks fellers! I appreciate the responses.

To answer some of the questions,

1. I'm using Tulip poplar. I didn't know there were so many different varieties. Tulip Poplar is very plentiful here in western NC. It grows tall and straight, and I have LOTS of it. I hope it's okay to build with. As a backup plan I could use oak, but it will be harder to find and drag out.
2. yes, I will have a loft in each bay. I plan to store hay up there, and some lumber probably. I dunno, 50lb/ square ft? I don't know how to estimate that.
3. "...which face of an interior bent the joints will be cut flush to."?? Let's say the east side.
4. the gable ends will face almost due east/west, so the side with the side shed and little man will be the north side.

btw, I'd love to have 40' plates, but I don't think that's possible.

Ignorance alert:
1. I don't know what is meant by the "general frame rule" about reduction or housing.
2. what is a brace pocket? as was suggested for the location of my scarf joints.

thanks y'all!
chris

[Jim_Rogers]

You need to read this post:

https://forestryforum.com/board/index.php/topic,6403.0.html

I think it is explained there about the perfect inner timber where the housing or reductions are cut to.

Also, a brace pocket is another name for a brace tenon's mortise.

Read the glossary of terms.

Jim Rogers

[ckprivette]

Thanks Jim. I love that thread. looking forward to the layout and cutting steps of my project.

[Jim_Rogers]

In an effort to help you, Chris, I contacted the TFEC (timber framing engineering council) an asked if anyone had the needed values for tulip poplar.

I got a response from an engineer in NC to contact a specific engineer in the group who has done work with poplar.
He did respond to me and shared the values with me. However he has requested me to keep these values private due to the fact that their client paid them to determine them.
So, what that means is I can't post them here.
I can however use them to size your floor joists, tie beam and plates, when I have time.

Jim Rogers

[piller]

Nice looking project, I agree with Razor's comments. 

The scarf joints in the plates would be at the brace connections in the center bay, you could put one scarf joint near the loft end and the other one near the other end.  Google "nps historic american timber joinery jack sobon" and download part six on scarf joints if you don't already have this one. 

I noticed that your tie beam and brace connections are fairly close to each other on the posts, I might want a little more space there.   How are you planning to connect the shed rafters?

As for poplar, I'm in East TN and we have quite a bit of it as well.  In Jack Sobon's book "Build a Classic Timber Framed House" page 52 he says this about poplar:  this fast growing and often straight and tall tree is very useful.  Trunks clear of of branches for 60 or 80 feet are not uncommon.  It's light, even-grained wood is easy to work and stable.  Like white pine, it has a multitude of uses and can be substituted for white pine in this frame.

[ckprivette]

Piller, thanks for the link and tips. I like hearing that "thumbs up" about poplar from Sobon.  8) For connecting the rafters I was planning to keep it simple by just nailing 1x4s across them. I plan to then screw metal roofing to these boards. Sound okay? The loft will be open, so I won't be concerned with the metal roofing sweating.

btw, up to this point the most difficult part of this project has been stump removal. I'm looking forward to progressing upward, instead of downward.

chris