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Old 12-17-2016, 12:23 PM   #1
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Bowed deck joists and blocking


Hi, I wasn't able to mark the rim board out where the joists should be. So I just measured from the ledger to the rimboard and nailed them in.

It looks decent but I can tell it's off a little.


My question is as far as blocking. Do I cut all the blocking the same size and force the joists in and out to get it closer? Or do I just leave the joists where they are and put blocking at the measurements the joists currently sit at?


Just to clarify. I tacked the two end joists in place and ran my tape measure diagonally and the deck is perfectly square. It's just the interior joists that are off. All joists are at a minimum of 12" OC

Thanks
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Old 12-17-2016, 12:26 PM   #2
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Old 12-17-2016, 02:03 PM   #3
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Re: Bowed deck joists and blocking


The only issue I see with joists which are not straight is if they are off far enough, the screws you use to install the decking will not be straight. But maybe you are planning to use hidden fasteners. Blocking can be cut to fit whatever the gap is, no need to force the joists to be straight, except for the fastener issue. Make sure the joists are attached to the beams using hurricane clips or similar if local code requires.
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Old 12-17-2016, 05:25 PM   #4
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Re: Bowed deck joists and blocking


Where's the joist hangers that should have been installed before the joist where installed?
Where are you located?
Never would have passed inspection around here without them.
Why 12" O/C?
How far below any door openings is the decking going to be?
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Old 12-17-2016, 09:43 PM   #5
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Re: Bowed deck joists and blocking


I would cut the blocks about a half of a saw blade shorter than what you measure to avoid bowing the outside joists.
Ditto on the comments above re: joist hangers.
Diagonal blocking can help to avoid the deck from swaying. I usually add some Diagonal blocks in both directions of a large deck. Usually in a "V" pattern.
And why is the one joist space so close together?
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Old 12-17-2016, 10:12 PM   #6
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Re: Bowed deck joists and blocking


Is the close spacing for composite decking boards? Are the specially spaced ones for the handrail/guardrail posts to be equal distance apart?

I see the required joist hangers on the house side ledger, not required per this Prescriptive Code if that is you, at the cantilever; http://www.awc.org/pdf/codes-standar...Guide-1405.pdf

The two mid-span girders should have been string-lined for straight to the rim--- or the rim to the outboard girder for square. The blocking should be to put the joist on the layout marks which all should line-up for straight, having a curve in the fasteners is amateurish, not at all professional looking, to say the least. Judging by all the leaves on the ground, you will have a lot of stored moisture on the deck boards/framing, with wet leaves taking extra long to dry. And PT wood is not waterproof, unless stated as such (and extra cost+$$$), or you apply an after market product- now. Even then, I would have used sticky window wrap on joist/beam tops, and the saddle on the post (and cut top); http://www.nadra.org/industry_news/d...s_that_rot.pdf

Be sure to chemically treat all PT cut edges where you cut the boards/posts. blocking over bearing is always good though may not be required, check locally on all of the above.

Gary
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Old 12-17-2016, 10:15 PM   #7
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Re: Bowed deck joists and blocking


I think the previous posters of pre-which covered all of the issues that are seen at this point. The lack of hangers is certainly a concern and when it gets inspected I doubt that it will pass inspection or at least it won't in most areas.
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Old 12-17-2016, 11:26 PM   #8
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Re: Bowed deck joists and blocking


The Code I work under would require blocking 2 ft on centre along both of the outside joists bays as well. Parallel rim blocking.

And Hangers at both ends.
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Old 12-18-2016, 12:20 PM   #9
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Re: Bowed deck joists and blocking


"I think the previous posters of pre-which covered all of the issues that are seen at this point. The lack of hangers is certainly a concern and when it gets inspected I doubt that it will pass inspection or at least it won't in most areas."--------------------------------- so you don't feel my adding to treat the ends is of a concern, covering the tops or that I said to check locally on all of the above- perhaps you missed that? Local areas usually add their own take on the codes, I was just showing it is not required to use joist hangers on a cantilevered end in that Deck Code, or any of the residential I-Codes, of which it was based. IF you are planning on adding more than the standard 40# per sq. ft. on the joists, it needs to be designed by an engineer. Then those prescriptive codes would not apply, though I doubt it would be"in most areas"as you said... maybe local areas for you. Be sure to turn the joist hanger upside down because right side up is only 3/4 of the stated load in uplift; https://www.strongtie.com/facemounth...uc.lu.u.hu.huc

Perhaps you have a link to hangers required at a deck/floor cantilever past bearing that you would share with me, I'm always open to new information, thanks!

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Old 12-19-2016, 03:04 PM   #10
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Re: Bowed deck joists and blocking


I have always wondered why people that build decks use thru bolting the support beams thru the 4x 4s instead of just using the 4x4s as main supports for everything above. When ever I build a deck or structure I always use the support mains 4x4s/6x6 whatever and put the mains on top I don't depend on the shear strength of the bolt thru's. Not a builder just saying. Not trying to hijack just had to comment.
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Old 12-19-2016, 05:57 PM   #11
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Re: Bowed deck joists and blocking


Not sure where this is....but if it were in Attleboro, ma, it would fail based on through bolting of the girders and lack of appropriate hangers/tie downs....without even I looking for the guys that attach to the end joists and blow to the inside of the rim board. Ron
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Old 12-21-2016, 10:00 AM   #12
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Quote:
Originally Posted by Daniel Holzman View Post
The only issue I see with joists which are not straight is if they are off far enough, the screws you use to install the decking will not be straight. But maybe you are planning to use hidden fasteners. Blocking can be cut to fit whatever the gap is, no need to force the joists to be straight, except for the fastener issue. Make sure the joists are attached to the beams using hurricane clips or similar if local code requires.
Good point. I didn't even think about the fastener issue.

I was planning on using the cortex hidden fasteners. I'll definitely be sticking with that now.

Thanks
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Old 12-21-2016, 10:01 AM   #13
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Quote:
Originally Posted by ront02769 View Post
Not sure where this is....but if it were in Attleboro, ma, it would fail based on through bolting of the girders and lack of appropriate hangers/tie downs....without even I looking for the guys that attach to the end joists and blow to the inside of the rim board. Ron
It's in Maryland. I'm
Not finished. I still have to install the hurricane ties and blocking
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Old 12-21-2016, 10:03 AM   #14
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Quote:
Originally Posted by joecaption View Post
Where's the joist hangers that should have been installed before the joist where installed?
Where are you located?
Never would have passed inspection around here without them.
Why 12" O/C?
How far below any door openings is the decking going to be?
Joist hangers are on the opposite side. Closest to the house.

It's about 1.5-2" below sliding door opening.

12" OC because I'm using composite decking
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Old 12-21-2016, 10:05 AM   #15
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Quote:
Originally Posted by jlhaslip View Post
I would cut the blocks about a half of a saw blade shorter than what you measure to avoid bowing the outside joists.
Ditto on the comments above re: joist hangers.
Diagonal blocking can help to avoid the deck from swaying. I usually add some Diagonal blocks in both directions of a large deck. Usually in a "V" pattern.
And why is the one joist space so close together?

Thanks for the reply. I have joist hangers just on opposite side.

The one joist close together is because of an exhaust vent that's in line with the ledger. Without that close joist. It would be 14" OC.

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