I'm wanting to make some sort of trellis/pergola thing to go over my my kids' play pit
I just finished making a garden bed to grow hardy kiwis and I want them to grow up and over the playpit. I'm thinking the easiest/cheapest way to make a sturdy trellis would be to use WesternRed cedar trunks from smallish trees.. I'm thinking of making something like:
or (without the fancy sides)
But, I've never built anything, unless you count a mallet. Do just use giant nails to hold it all together, or carve the spiffy peg ends on the upright wood and stick them into holes in the logs that are perpendicular to the ground?
The first one is very nice. It would take a long time!
The second one is very quick, it won't last a long time!
Structural screws(Brands include Timberlok and GRK RSS-Rugged Structural Screws), are very much your friend if you do not wish to spend a lot of time. In fact even if you do wish to spend a lot of time doing mortise(holes) and tenon(spiffy pegs), you might choose to lock it all together with structural screws rather than hardwood dowels.
Do take the bark off. Especially with cedar as it's so easy to peal.
Ideally take the trees/poles down in the spring as the sap begins to flow to make peeling even easier.
Do get the post bases up off the ground, ideally... even cedar rots out in the PNW.
Do lots of bracing, like the first picture. The braces should be in line with the posts/beams so the force transfers nicely. The second picture has slapped diagonals against the side of the post and used a fastener which will now have all the force transferred through it, in a bad way. Fasteners are fine, as long as they're good ones, but this is a bad way to use them. I have seen snapped structural screws even in tiny structures when used this way, as the force on them is enormous.
Wood used as a post can generally be smaller than one would expect. Wood used as a beam generally needs to be larger than one would expect.
Because this will presumably not have a roof, it would be nice to avoid fasteners on the top of the top beams, as this would be a nice spot to catch water and accelerate decay.
I recently read Rob Roy's 'Timber Framing For the Rest of Us'. It was full of things I've learned already, sometimes the hard way... but still a fun quick read like most of his stuff, and had interesting ideas and bits of data I hadn't seen before.
It would be a great read for somebody just starting with this stuff!
Have fun, building this sort of thing is awesome and your kids will love climbing on it!