Need creative bracing ideas

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Old 07-29-20, 08:14 PM
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Need creative bracing ideas

Hello everyone!

So last year my wife and I had our deck replaced by a contractor because while I am capable, I generally know my limits and it was a significant undertaking. We replaced our 12x14 with a 20x28 composite deck. On the long side of the deck we added a large bump out for our grill. Since then we have added a blackstone griddle to the family and as much as we cook outside in all weather, the natural progression was to build a roof over the grill bump out.

The area covered by the new roof is 16' by about 7'. It will be a metal roof when I'm done. Currently the top does not rack at all, and movement side to side down the long axis is minimal given the deck railing holds it in check. What I need some ideas to overcome is front to back sway on the short axis. The idea of course being to not build a visually displeasing structure, and given the post locations that are offset front to back, I don't want to build diagonals that go over top of the grills so-as to not create a fire hazard.

All that said, I completely accept that a contractor would likely have expected and planned for these challenges. My goal here has always been to take my time and build something nice on my own terms that I could take ownership off and be proud to share with my family. I would very much appreciate the opportunity to learn from anyone who is willing to share their knowledge. Thanks in advance for your time!



 
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Old 07-29-20, 08:22 PM
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Do your 4x4 posts go through the deck and bolt to the joists or to blocking between the joists? Or do they extend down to a footing and sit in a post base?
 
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Old 07-29-20, 08:48 PM
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They are bolted with 1/2 bolts to the joists with blocking added. Each post was bolted with two bolts to the joists and one bolt on the opposite axis through the blocking and rim joist. The blocking was secured with a combination of 16d nails and structural screws.

I know I can't rely on a rim joist for anything structural, but my contractor went to great lengths to make that rim joist crazy sturdy when he built the deck. While it can't officially be counted on, it's definately not hurting me on the stability front from what I can ascertain.
 
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Old 07-29-20, 09:00 PM
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My only idea would be to somehow connect the front and back posts with stainless steel cable crossbracing.

if this could be done as low as possible, behind the existing railing, it wouldnt be as visible. You would need eyebolts, cable, a swaging tool, and turnbuckles. By keeping the posts in tension equally, it will prevent them from swaying just like crossbracing would.

Another method that would not be quite as effective as crossbracing, but similar would be to take the cable up one post, through or over the beams across the roof and down the other side. By tightening the cable down (maybe with turnbuckles under the deck) you would be forcing the structure into a square shape that would not want to rack. (The tighter it is, the less likely the cable is to slip and slide)

Even one cable on each side would be better than nothing. Like maybe from the ends of your cantilevered beam down to the bottom of each front post.
 
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Old 07-30-20, 05:19 AM
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An observation. It appears the roof overhang on the side opposite the railing is large enough that a snow load could be a problem because of the cantilever design. Where are you located?
 
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Old 07-30-20, 08:01 AM
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We

We live in western Maryland. Not up in the mountains, but nowhere near the coast either. I braced the hell out of the low side of the cantilever with double 12" hurricane straps for snow load protection and the same on the fulcrom beam to aid in uplift protection. I also added more security to the post/beam connections on both beams to attempt to limit weak points of failure for those forces as well.

As I was plugging away on this idea, I solicited some opinions of friends that are in the industry and was convinced that it would be stable. They actually told me I had room to grow another foot or so, but that just didn't "feel" right when I did some testing as I went along. I'm a pretty big guy and can hang freely from the high side of the roof with no flexing observed. Ive extrapolated, perhaps incorrectly, that with the roof holding to that point load it should perform reasonably well for a distributed load for snow as well.

What do you think? Thanks so very much for the feedback!
 
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Old 07-31-20, 04:50 PM
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Can't comment any further as I am not a structural engineer. Hopefully your friends advice is good advice. You will have the proof after a few winters.
 
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Old 07-31-20, 06:16 PM
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Thanks, I appreciate the well wishes.
 
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Old 07-31-20, 06:48 PM
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Make sure you youse two nails per purlin into the rafters. After you add the metal roofing (assuming it is pole barn tin) it will likely stiffen up quite a bit.
 
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Old 08-01-20, 06:37 PM
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4 4X4's with a roof structure is going to sway like the devil without any cross supports. Looking at the rest of the structure, you would have gained substantial stability if your railing system was integrated into the 4x4 supports as opposed to floating them and having floating handrails between them. Yes, once the steel is on it will damper some of the movement, but truth is, this is a structure that should have been run past an inspector before being built.
 
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