[magicone2572]

Just a general question. What are some options other than dimensional lumber for deck joists? My span is going to be 15.5' from edge of one beam to the other. Using standard PT lumber is going to be a nightmare at those lengths due to the inability to get straight lumber anymore.

I looked at Trex Elevations but wow, I'd be spending $6k+ just on joists. I-Joist or LVL's would work but they aren't weather rated. Or is there a way to still use those? Any other options?

 

[Windows on Wash]

You can reverse engineer the Elevations system if you want to be inventive.

 

[magicone2572]

You can reverse engineer the Elevations system if you want to be inventive.

I've thought of that. But I'm guessing I would need an engineer to sign off on it, have the metal yard fabricate/cut then getting the inspectors to approve it. Not sure how much that would cost vs the elevations.

 

[de-nagorg]

May I suggest that you go to a REAL lumber yard, and hand pick all your material.

Most of them allow you to do this, if you want to.

I have had the yard crew help me picking my materials.

And if you discover any that are "rejects" after delivery, you can return them for replacements.


ED

 

[magicone2572]

May I suggest that you go to a REAL lumber yard, and hand pick all your material.

Most of them allow you to do this, if you want to.

I have had the yard crew help me picking my materials.

And if you discover any that are "rejects" after delivery, you can return them for replacements.


ED

Yeah we have some good ones here in MN but still, how straight can you get a 2x12x20 in PT even top grade? Or do I put a mid-beam and split it with 2x10x12 on each side?

 

[de-nagorg]

Yeah we have some good ones here in MN but still, how straight can you get a 2x12x20 in PT even top grade? Or do I put a mid-beam and split it with 2x10x12 on each side?

Why do you need 20' lumber?

You say the span is 15.5'.

That wastes 4', that you won't use.


ED

 

[chandler48]

You could use 2x10 lumber if you were to drop your support back to 13' and cantilever 2' over the edge. Just post and beam the length at the 13' mark.

 

[magicone2572]

Why do you need 20' lumber?

You say the span is 15.5'.

That wastes 4', that you won't use.


ED

So the deck will be 42'x20'. But there is a block wall 3' out from the house that will support the house end of the deck. They will sit directly on top of that. Then span out 17' to make it 20' total distance.

 

[magicone2572]

Hopefully this picture makes it easier to understand. If I had a mid span beam, I'm only then spanning 8' or so. Then I could get by with 2x10x20's. Still will be hard to find straight.

 

[chandler48]

You could get by with 2x10x10's if you made your mid span beam flush with the bands, and attach the 2x10's to the beam using joist hangers. May be easier to find straight 10 footers than 20 footers.

 

[magicone2572]

You could get by with 2x10x10's if you made your mid span beam flush with the bands, and attach the 2x10's to the beam using joist hangers. May be easier to find straight 10 footers than 20 footers.

That is a really good idea! Thanks

 

[chandler48]

Another reason for splitting the load would be, while you can span 15 or more feet with 1x10 or 2x12 lumber, you will still have a bounce factor, which you will eliminate with the mid span beam.

 

[magicone2572]

You think a double 2x10 flush beam would work then?

 

[chandler48]

2x10 will depend on the spacing of your posts. Here's some good stuff to read regarding your post and beams and their placement and attachment.

https://www.awc.org/pdf/codes-standards/publications/dca/AWC-DCA62012-DeckGuide-1405.pdf