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I'm planning a rain canopy down the side alley of our house. The basic design in mind is to have several vertical timbers attached to the ground and bolted to the wall. The schematic below illustrates from side-profile perspective. The canopy is corrugated panels - the blue line from joins #1 and #2. From side-view the timbers form an isosceles triangle with an angle of 40° at joint #2.

My question is which joins would be well suited to joints #1, #2 and #3, considering the nature of forces in the structure? Most weight will be directed through the verticals to ground, with wall screws only keeping the structure attached to the wall. I could to be honest easily get away with bolts for this project but I'm interested in what good joinery approach would look like.

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  • Hi, welcome to Woodworking! I'm glad you said it because yes, you could get away with nuts and bolts for all of this; so keep that as a backup should none of the joinery options pan out. 1, 2 and 3 can all use the same joint. This wouldn't be the case with large members in certain timber-framing traditions (where 3 in particular would tend to be a unique joint) but for something that doesn't literally need to support an entire roof assembly and the weight of the roofing materials on top of that it's overkill, although still being an option. I suppose the main thing is what you're setup [contd]
    – Graphus
    Commented Aug 27, 2023 at 19:27
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    ...to do, along with what your experience level might permit — like, at one extreme would be some of the intricate Japanese joints, which only an experienced hand-tool woodworker would want to tackle and have much hope of doing well..... three times over! But there are some much simpler options you could do that rely mostly on adhesive strength, with some basic table saw or router setups and minimal manual cleanup after.
    – Graphus
    Commented Aug 27, 2023 at 19:29
  • Thanks @Graphus. Yes I think I'll stick with bolts. But I guess corner bridle joints with dowels might've worked for #1 and #2 and mortice/tenon at #3.
    – geotheory
    Commented Aug 27, 2023 at 20:49

1 Answer 1

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I could to be honest easily get away with bolts for this project but I'm interested in what good joinery approach would look like.

Yes nuts and bolts could be used for this, so it's worth keeping it in mind as a fallback. Do note the potentially difficult cuts for joint 2.

Aside from just bolting this together other non-joinery options include the use of external fixing plates of some kind, such as those made by Simpson (although there are numerous other brands of such steel joint/reinforcing plates, along with plenty of generics).

There are numerous joinery options, some of which come from timber-framing traditions. Ignoring the really complex joints (complete overkill for this application) and in ascending order of difficulty1 here are some you could use:

  • Butt joints (end-to-face, with a mitre at 2), reinforced with nails, screws or dowels/pegs, and maybe a spline added at 2.
  • Butt joints at 1 and 3 aligned with one edge of the uprights, reinforced with gusset plates (could be steel or plywood).
  • Lap joints/halving joints for all three, glue-only or reinforced if desired.
  • Half-dovetail lap joint for 1 and 3, bridle joint2 for 2.

With any of the alternatives used at 2, here are further options for 1 and 3:

  • Dovetails.
  • Mortise and tenon.
  • Notched joint/birdsmouth, plain, pegged or screwed.

1 And many would say, also in ascending order of strength. I would argue however that lap joints throughout is the simplest 'proper' joint (one offering some mechanical advantage) and potentially of equal or even greatest strength, based on some comparative test results of the raw joint + a number of reinforcement options.

2 AKA an open mortise and tenon.

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    Thanks very much Graphus. Will look at the additional options you suggest. Glad it seems my thinking is broadly on track.
    – geotheory
    Commented Aug 29, 2023 at 9:42
  • Welcome! Glad it was of some help.
    – Graphus
    Commented Aug 29, 2023 at 19:47

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