Span charts/calculator for 4x lumber

[DeformedTree]

I've been wondering the same thing.  Why do you want 4x for joists?

There’s odd times where there is a lack of space for the typical 2x applications, say where a 2x8 would be the norm, but with insufficient room for it perhaps a 4x6 may work. A span chart for 4x materials could answer the question with more certainty.

It has always been my understanding that a 4X of a given width offers less strength than a pair of 2x of the same width.

This is what I touched on above. It's not so much that it couldn't be stronger or as strong, it's just the issue that wood is a natural product with flaws. Using multiple timbers reduces the risk of flaws (not as likely to fall in the same spot).  Engineered wood takes this to the extreme and thus gets higher ratings.

Look at old multi member beams. Very normal for one of the 2x's to have sagged more than others.  Had this been 1 timber instead of multiple, you could have had the timber cut from the same tree that sagged more than the others and now the whole beam sagged/failed.

This is where timber frame construction makes me nervous (even if beautiful).  You have a fracture critical structure as you no longer have the benefit of statistics in the framing.

I get if the idea behind wanting to use 4x lumber was looks, sure it looks much nicer than laminating 2x's, but it can present issues.

 

[Paul G]

Hurricane Whisperer, I agree with your comments. That’s why actual charts or calculators are so helpful, providing real numbers instead of rules of thumb.

 

[Paul G]

If joist height room is an issue, then you should consider using either LVL or TGI if in interior spaces or a making a 'flitch' if the weather can get at it. If going flitch route you'll be doubling the 2x lumber regardless.

http://www.strucalc.com/tag/flitch-beam/

Yes, engineered products can be an option.

 

[Hurricane Whisperer]

Hurricane Whisperer, I agree with your comments. That’s why actual charts or calculators are so helpful, providing real numbers instead of rules of thumb.

I think if you understood the comments, then you wouldn't be asking for 4x floor joist charts.  Deformed Tree added yet another reason why 2x lumber is used even if doubled up to make a 4x header or other part of the structure.

 

[Paul G]

Hurricane Whisperer, I agree with your comments. That’s why actual charts or calculators are so helpful, providing real numbers instead of rules of thumb.

I think if you understood the comments, then you wouldn't be asking for 4x floor joist charts.  Deformed Tree added yet another reason why 2x lumber is used even if doubled up to make a 4x header or other part of the structure.

Here is what I hope we can all agree on, all other things being equal, a 4x8 will hold more load than a 2x8. The charts or calculator helps a non-engineer know how much so. I understand sistering is probably even better (depends on how those pieces are joined), adding steel into the mix even better. And I understand it isn’t in the norm of current practices. It was just a simple request for data that I couldn’t find, no need to make more out of it than there is.

 

[Cheese]

I'll routinely use aluminum flats if I need additional strength without the thickness.

Here's a 3/4" or 1" thick aluminum flat sanded on the rear surface to remove the oxide coating and to add some tooth.

Fastened to it's own aluminum base, top & bottom.

Adhered to the existing 2x material with PL 400.

Secured to the 2x material with #12 construction screws.

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