levelling decking with crowned joists ?

[topov]

Need help with a small decked area I'm building;
I've made a frame of 4x2, which will sit on feet on a concreted area.

Some of the joists had a a curve/crown, and following posts on here, I put the crown uppermost (higher in the middle). I guess the hope is that it will sink over time.

My 1st question is: should I put feet/supports under (or near) the crown ?
....If I don't, they could be a bit bouncier than desired.
....If I do, then they will never sink down, flatter.

And second question: right now the various crowns mean that the tops of the joists are not level with each other.
- so when I come to put the decking boards on ... what should I do ?
....force down the crown (if not supported underneath) and hope that the boards will keep the joists forced down, in line?
....or let them be not level, and accept that the boards are going to be sloping up and down a bit as they cross the joists?
....or do I need to put shims on top of the non-crowned joists to bring them up to the same height as the highest ? (but then if the crowned joists ever straighten out, the shimmed ones will then be higher)

(the board are 21mm thick hardwood (garapa) in case that makes any difference)

Hope someone can help

 

[WabbitPoo]

I never put crowns upwards - put them downwards, and force them up level with supporting posts.

You were given duff advice, in my opinion.

 

[topov]

Oh.

the third post on this thread ( //www.diynot.com/forums/viewtopic.php?p=913084#913084 ) was one of them, From Thermo:

sounds like youve not checked the crowns o the joists. All timber will have a crown to it, ie a slight bow on one side. You can see it looking down the length of the timber. The joists should be laid crown up, and as the weight goes n them over time they will settle. If its not to late then turn the joists now.

 

[WabbitPoo]

If you have posts concreted into the ground at the point of crowning, you could force the crown out of the timber and then fix to the posts, so holding the joists level.

 

[topov]

no - the area is already concreted, so I was just going to rest most of the posts on the concrete, with a few of the post fixed to the concrete using metal brackets.
But - going with your idea, I suppose I could make sure that the metal brackets are under the crowns, and force them down before fixing (and hope that the fixings will hold it down).

 

[rjm2k]

I didn't notice any joists bowing like yours when I just did my decking. Some bowed horizontally but not vertically.