I am putting up a 24 foot sail shade half above my pool and half above a soon to be deck next to the pool so I cont put posts in the middle of the pool I’m using 4×4 posts and 2×6 in between but my posts have to be 28 feet apart to tie the shade onto so my question is how how can I support that span so it does not sag and how do make it across 28 feet without being able to get 2×6 that long
Please help
Replies
So build a truss out of 4x members to span the 28 feet.
I started with a pile of 16 foot 4x6s & 4x4s and some plywood to build a 4 bent pavilion. It was support by (8) 4x4 posts on a 28 foot x 16 foot grid. It survive multiple 12" snowfalls until age took it down (the lumber was never sealed against the elements).
If this is simply a shade sail and will not experience loads beyond heavy rain & wind (i.e. no snow loads), you should be fine.
Another point to consider is that you should use a four point sail to prevent any sagging over your pool. Something like this: https://www.aandslandscape.co.uk/product/maxima-sail/
I had 3 big sails over my patio for a couple years. I started with 4x4 and the bent in like a wet noodle. I anchored one side of the sails to the wall and the other sides to the post.
So the next year I decided to put 6x6 in and pitch the at a 10 degree angle. They were about 3ft in the ground with concrete. After I tensioned the sails everything looked good. Then a couple weeks later wet noodles and sagging sails.
I even pitched the sails at different angles but couldn’t keep the tension on them to not sag.
I think the only option for posts and sails is a telephone pole or a steel pole. The sail take an incredible amount of tension to get them right and not sagging.
So I cut my loses and bought two purple leaf offset umbrellas that are 10x13 attached to a base plate in the ground. So far so good.