Uneven joists for composite decking

Old 05-02-18, 01:23 PM
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Uneven joists for composite decking

Building my first deck. Just wondering what the tolerance is for variations in joist heights. I'm just trying to avoid the appearance of a wavy deck. Should I be worried about 1/8", 3/16", 1/4"? Where do you guys draw the line?
Old 05-02-18, 02:23 PM
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Some composites are more likely to show waves than others. I would shoot for no more that 1/8".

Are the joists set on a ledger, or on joist hangers. Either way, you either shim the joists or remove small bit to even them out.

Some composites recommend joists that are 12" on center so double check. What brand of composite are you using?
Old 05-02-18, 03:51 PM
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Always a good idea to get them as flat as possible. I generally will power plane joists to make them straight.

Problem is with time and weather the deck usually warps a little anyway. Some guys like to use crowned joists on decks... (creates a prestressed deck) if that's the case you wouldn't plane the crown off.
Old 05-02-18, 04:40 PM
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I think composite is a lot like a vinyl floor in how well it telegraphs inconsistencies from below. I would shoot for as even as you can get.
Old 05-02-18, 04:52 PM
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I've built 3 composit decks with various styles of decking and befroe that 3 wood decks (never again) even now with a 10 year old deck that I'm sure has changed shape due to structure boards warping and drying out nothing is any more obvious than any other material.

I would agree, anything under 1/8" is not an issue, anything greater and I'd be changing it out regardless.

BTW you will never regret the decision to go composit, just did a clean up on the current 10 year old deck and it still looks, and feels like new.

Have never had to stain, never had to replace a board, never had to sand, that's the long term savings!

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