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Reducing sway on a tall deck

7K views 14 replies 11 participants last post by  joeyinsouthaustin 
#1 · (Edited by Moderator)
Hi all,

I built a fort for my son last summer. With the help of an experience carpenter, I'm pretty happy with the results (photo does not show it complete) . To reduce sway, I used Y bracing attached with 6" deck screws and it's not doing the trick. Would it be enough to reinforce with lag bolts or do I need x bracing.

Secondly, if I use x bracing, what's preferred? One long span from corner to corner or can I make several x's between each post? The footprint is 16'x16' so a span from corner to corner would require several 18' or greater boards.

Lastly, if I do make several x's between each post, could I leave the front open above the slab without sacrificing rigidity. Eventually, I'd like to build a small shed underneath and need the access.
Thanks
Building Tree Plant Wood Window
 

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#3 · (Edited by Moderator)
X bracing between posts will be adequate. Don't use deck screws - they are too small for the shear loads. Use several 3/8" lag bolts with washers to fasten the braces.

If you have the ability to locate the X frames near the center of the structure (under the house), you may only need one X frame in each direction. I'd connect the bottom of one post over to the top of the next post. That may be all you'd need. If it is still wobbly, you could add more.
 
#4 ·
What splinter said. 3/8 or 1/2 lags 6" long. Pre-drill a tad under and use an impact, if possible and drive them home. You could hide the bracing within your storage shed frame-up on 3 sides and leave one open for the doorway. Nice fort Dad! Looks like a cool neighborhood hangout.
 
#6 ·
I want to take a different stand. The bracing shown is too short. If those boards were longer they would brace the entire length of the post. those are only a couple of feet long and they only stiffen that much of the post. The screws used will make a lot of difference but on the sway. The screws will break if they are deck screws. Nails will not break. Normally lag screws will hold the best. Bolts and flat washers are good. Use flat washers to keep the heads from digging in.
 
#9 ·
actually he ledger locks that Joey suggested are superior to plain lags in pullout and splitting with or without pre drilling the hole for the lag. they are not just a glorified Sheetrock screw and they are specifically engineered for use in this type of construction.
 
#11 ·
Hopefully I wasn t misunderstood. The bracing does need to be longer like splinter stated…and use lag bolts. I agree with grandpa also about the washers. That screw looks like a good one joey, but it wouldn t be a good one for this application.

- freddy1962
Thanks for the backup REO That whole line was in fact developed for exterior decking situations.n They are all rated and tested for code. They make a GREAT thru bolt as well. As long as 3 4X members without predrilling, and without getting out the rachet!! I just finished rebuilding and stabilizing a 20,000 square foot cedar deck. The whole line is exceptional in every way.
 
#12 · (Edited by Moderator)
As firefighterontheside said, if you are going to make a shed below, and the span is less than 8', you can span it with plywood or even OSB siding and it will stiffen the structure wonderfully.

It looks longer than 8'. You can make longer plywood using scarf joints as shipwright shows on one of his boat builds. You would have to ask him if such a joint is strong enough for this application.

Best scarf post…
http://lumberjocks.com/shipwright/blog/25384

Another one…
http://lumberjocks.com/shipwright/blog/19783

-Paul
 
#13 · (Edited by Moderator)
Try adding longer braces parallel to the ones you already have; double braces. Or, build your shed now; that'll stiffen 'er up real good.
X braces would seem to be hard to get around (ducking, stepping over, etc.), especially when used in more than a few places. Or use X braces only where you will build your shed; remove them when you build the shed.
 
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