Pressure Treated Lumber - dimensional variations in joists

I am building a freestanding deck - consisting of two rows of 2x12 beams with 2 x 8 joists on 12" centers - deck surface will be 2 x 6 on 45 degree angle.

I laid out the joists and screwed them to the rim joist (24" cantilever past beam)before securing them to the beams themselves. I'm using Simpson Hurricane clips.

Here is my issue - the height of the joists vary by up to 3/8" so when the top surface of each joist is flush with the top of the Rim Joists there are sections of joist that "float" over the beams.

It looks like I have to secure to the beams first then let the rim joist be uneven - aligning to the lowest joist in the series of 22.

Any suggestions?

This is a permitted/ approved home owner project -

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Feb 16, 2012
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Southern Yellow Junk - Pondersa Pine Better
by: Anonymous

That's the problem with southern yellow pine, you'll have to plane them down. You would have been better to buy ponderosa pine.

Sep 21, 2011
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Great questions - tips to level joists
by: Editor-Rich Bergman

This issue of joists not always sitting flat on beams is not uncommon. There are a couple of ways to solve this.

Joists often have crowns. Always arrange your joists so the crown is facing up. Over time if the joist sags it will fall into level.

But you should try to pull the joist down, if it has a crown AND assuming the beams are level and then screw or double toe nail the joist to the beam. You should never leave a gap between the joist and beam. You should shim between for a contact point. But if the crown is too pronounced you could end up with an unlevel deck surface.

How do you pull down a 10' long joist with a 1/2" or greater crown? Very hard to do. Yes it is. And I solve this very easily using a tool developed and sold at our store called the Deck Devil Board Straightening Tool. But it does a million things more than just straighten boards.

Check it out here to find out more.

To summarize, its not always easy to guarantee that all beams and joists are perfectly straight or level. Whatever the situation, your end goal is to ensure the top surfaces of all joist are level or very close to it. Set the joists at those points and then if needed shim in between all joist and beam gaps.

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