Laminating plywood for pergola rafters

[ub_268]

Does anyone have experience with laminating plywood for use as rafters in pergolas? I have half a dozen 5m lengths of bent 70 by 40 timbers (3x1 1/2 in old speak I think). They've been bent in the rain and humidity and bunnings threw them in a $5 bin. i've clamped them to make their crescent bends uniform. I want to concrete in a couple of steel posts and beams and create sale effect with the bent rafters suspended by the centred posts.

But I think the 70x40 are too small for rafters. So I wondered if I could bolster them sufficiently by encasing them in ply? Ultimately, I need to have some plans for council, but maybe someone in the community has advice.

brian

[ub_268]

Thanks everyone for encouragement regarding my pergola idea. I've been busy terracing the slope from the bottom up. I can see why this wasn't done by previous owners! I'm using 200 by 75s (8 b 3s) recycled hardwood and the specs in the attached pdf as a guide, as well as listening to people. the concern is the specs say it assumes a slope of no more than 1 in 6. My slope is more like 1 in 2.5! Even 0.8 in 1.5! About 22 to 28 degrees not 10 degrees!
Does anyone know about no-fines mix? It's a mix of cement and aggregate only. No, or very little sand. It remains porous. It's encouraged by the Allan Block system. But it sounds like it might be good for my post footings as well. I'm also wondering if I can make up my own mix of copper sulphate to use along with linseed oil for the timber.
Any thoughts?

[ub_268]

Sorry, I couldn't find the upload document link for the retainer wall specs. Basically, I'm working on maximum wall heights of 800-900mm and a minimum of 1.5 m between retainer walls (though I thing it's given in a formula in the specs I think) and about 1.2 m between posts in the wall and placing two posts in a right angle orientation at the corners. Depths, using hardwood, isn't quite as much as the post is above the ground. The drainage will take some digging.

[BIM_Engineer]

I suggest you get clarification on the different retaining wall systems and Calculation requirements from your Council Building Department
Generally, the Council will require plans, Elevations,spot levels, Engineering Details,notes, calculations and certification.
.eg here

Post & Rail Retaining wall BIM Details & Notes hth

[ub_268]

Thanks BIM. I posted the web page that I think you're alluding to in your uploads. Unfortunately, they didn't come out well. But the thread is pretty old now.
Can you help me again? I've concreted in 1 and half of my three-post retainer wall tiers that I'm doing on that slope, as I try to work from the lower level to the upper where I want a pergola. And I'm happy with the no-fines mix. (How do I upload a photo?)
What I'm keen to do, not wanting the other side of the drive to feel left out, is to build an elevated den abridging the upper terraced garden and the space over and beyond the existing retainer wall. I'd send you elevation plans and photos but I can't remember how I uploaded last time. I'm thinking I could implant two posts into the lower terrace and two into the top terrace and construct the framework on those for a 3 by 3 structure. The taller pair of posts would be 2.5 m above ground level.

[Jason]

Hi @ub_268,

Photos will help @BIM_Engineer and other community members better understand what you are working with, so I certainly encourage you to add them to your posts. 

To add photos to a post, make sure you use the red reply button to access the post editor.

Then you'll find you can press the Photos button or the Upload Images button (either is fine). You can add as many images to a post as you like.

Please let me know if you have any trouble.

Jason