Wood straight, come off it!

[Tiger]

Dear all,

Need some advice on plumbing posts for a pergola. When I built a small pergola, I spent a huge amount of time selecting timber that was straight, thinking that if I didn't get that right for the posts then I would have a skewed pergola. In the end, I selected 4 posts that were acceptable but hardly straight along their length. The fun and games came when I attempted to plumb them just before putting the concrete in.

My question is how vital is it that you get a 100% accuracy in plumbing the posts? What if you're a little out? It seems damn impossible to get a 100% accuracy result along the entire length. Do you attach your level to a long straight edge and use that? Is near enough, good enough? I am thinking about extending the pergola and therefore would need to go throught the same exercise again. Why do diy shows and books assume that every bit of wood that you use in construction is straight when it's not?

[wishiwastommy]

My advice is borrow a straight egde (or a straight bit of timber to use with your level). Near enough is good enough though. Depending on how high it is (assuming 8 ft) you could be out 10mm without any significant problems.

*mark

[Skew ChiDAMN!!]

Generally speaking, near enough is good enough.

For long posts, don't bother futching around with levels & straight edges, use a plumb-bob (a string with a nut tied on the end) hung from a nail in a top corner of the post. Simply make that top corner of the post align with the bottom corner. If the bow interferes with the bob, just move it to another corner! :D

This is a much easier method (unless you have wierd gravity vortices in your corner of the world) as it leaves both hands free to adjust the post and fasten the bracing to hold it there...

[julianx]

heres a couple of points
1 use a 1200 mm level
2 make sure the level is level and plumb
3 face the rounds (convex side of bow) in the same direction on each post
rounds out and up hollows in and down
4 put the level in the centre of the hollow to plumb the post

5 if the posts are longer than about 3.3 use a plumb bob
6 dont forget plumb and straight are two differant things