Simple questions from a beginner

Hi everyone

I've been involved in residential construction for 4 years. Now I'm about to take my first stab at mortise and tenon joinery.
I'm building a wood shed for my old man, next to his beloved outdoor wood furnace.

Located in central Ontario, posts will be anchored atop concrete piers 4' below grade.
6x6 posts and girts, 6x8 plates, 3x5 braces
1.5" Joinery

Couple pictures, I will remodel after I decide on a final plan...




I have a few questions ...

1) Solid top plates are not an option. Will a spline joint be sufficient above the two middle posts? Or should I give the covenant scarf joint a go?

2) 3" girt tenon length suitable?
3) 2" brace tenon length?

4) 3/4 or 1" pegs?

5) How critical is straight grain green hardwood for the pegs? Can I get away with green pine?

6) 2x rafters with birds mouths toe nailed to plates? (Cheating I know, but this is a good starter project)

Special thanks to Northern Lights for the tf_rubies, I would love to donate any extra cash but I love carpentry and farming, so extra cash doesn't exist.

Thanks in advance

One thing that concerns me is having the two braces going into a 6 inch post. If you have housings, you won't have much of a tenon on your braces. I would go with 7"x7" posts.

You don't say what dimensions the shed is, 12'x20' maybe? Also, what length timbers do you have available for the top plate. That will determine how you splice the two pieces together, which would ideally be over a brace.

1) Solid top plates are not an option. Will a spline joint be sufficient above the two middle posts? Or should I give the covenant scarf joint a go? Being your first project, dive right in and make a scarf.

2) 3" girt tenon length suitable? Probably not
3) 2" brace tenon length? 3" is standard

4) 3/4 or 1" pegs? 3/4" for 1 1/2" joinery

5) How critical is straight grain green hardwood for the pegs? Dry hardwood would be better, and stronger.

Can I get away with green pine? I wouldn't.

6) 2x rafters with birds mouths toe nailed to plates? (Cheating I know, but this is a good starter project)
Ok, I guess.


Dave: Picture shows 13' x 28'

5) Green wood works easier. They will dry quickly.

Pine for pegs? Spruce would be better, and even better, some variation of hard wood.

6) That is not cheating.

1) a wood shed is a good place to practice, it is small and perfection isn't as essential. So it's a good place to make your first scarf. Better here I'd say than on a house or somewhere, where a mistake would be disastrous!

4),5) the quality of your pegs depends a lot on how you raise your frame, and how the various timbers interact with each other. with braces, the joints are always supposed to be in compression, and there are a number of historic examples of braces being pegged with twigs, just there to hold them together until the frame is up in which case it should hold itself together.
If you have a simple mortise and tenon tie joint, than it is in tension and the peg is very important.
Some historic frames, especially in Continental Europe, may not have a single peg in the entire frame!

6) around here, that is the way it was done on about all barns. The rafters and joists are generally 2x (true 2x, not 1 1/2 stuff you get nowadays) and the rafters are birdsmouthed and spiked in place with gigantic spikes, like a modern polebarn spike.
the disadvantage of this, in our barns the rafters were often staggered at the purlin, with a different rafter for the top section and the lower section. As a result, you can see the purlins from the outside of about every barn around, the roofs have sagged and the purlins have heaved upward. The purlins in this style of roof have more upward force than the downward force exerted by the rafters, and so the result is a net upward force which shows up after 100 years or so... This combined with the tendency of 2x rafters to sag significantly over time causes the roofs to be very wavy.

DLB

Since this is your first attempt, have you worked with anyone to learn proper technique? There are techniques of layout, and cutting joinery which are efficient. There are also those who have no idea of technique and fight the wood, the tools etc. There's a lot to be learned, though not rocket science by any means, via a 3-6 day timber frame workshop, or working with an experienced timber framer, that may save you a lot of work, and wasted effort. Something to consider.

Pegs should be hard wood. They don't have to be green when installed, but when making them yourself, they are far easier to work green than dry. And usually by the time you go to use them, they are dry. When making pegs, split the green hardwood log chunk with a froe, and throw the blanks in a tub of water until it's time to shave them. A rubbermaid with water works well. There are a bunch of other tips for making pegs, just ask. After you split the blanks you can probably shave about 1 every 1-2 minutes on a shaving horse.

The project is small and a few things will go a long way to doing it just right so a couple optional joinery comments if you want to make it a little better.

-Use a proper timber splice joint at the plates. And to emphasize what Dave said, the best and strongest place to position the splice is not over the post.

-Don't hold the posts together with pegs. Use a wedged, half dove tail with the tie beams for this job.

-Use timber size rafters ideally with step-lapped seats.

-Since you only need a small quantity, note good pegs can also be made with just a chisel.

Thanks everybody

The shed is up, steel roof is on, and it is solid.

Hemlock frame, Pegs came from old potato crates, mixture of ash, maple, and elm. Made them on the table saw (not the safest thing I've done).

I regret not using a wedged half dovetail for the girts. I can now see the importance, I will do that in the future.

I did my first stop splayed scarf with wedges, turned out okay. Its not perfect which drives me crazy, but its working. I did have to place the scarf over the post, because of timber length available. I spliced together the rear top plate with a maple spline.

Bird mouth rafters, toe nailed down.


Just waiting for some board and batten to put up, then its done.

I'll post some pictures when it is completed, thanks for all your advice. I hope I can contribute to this community in time.