Load equivalence of hard and softwoods

[JHZR2]

Is there a table/rule of thumb for equivalence of hardwoods and softwoods for loading and/or deflection over a span? For example, a 1x3 oak plank is equal to a 1x4 maple is equal to a 2x4 dimensional fir/pine? Just curious, of course it seems that this is never done due to cost, but it's just general interest. I've seen tables with densities and tensile/compressive strengths..

Thanks!

 

[bepperb]

The Sagulator is what I use. To be honest there isn't a huge difference and I just assume everything the same. The only time I would think otherwise is with OSB/MDF/plywood which have considerably more sag.

http://www.woodbin.com/calcs/sagulator.htm

Anyway, I think you'll find that softwoods are at least 75% as rigid. No way a 1x3 oak is as strong as a 2x4 fir.

 

[expat]

Older span tables give acceptable spans, dependent on lumber dimension and species.
I have also seen old (British) Royal Navy records that state the properties of numerous species of wood.
I guess in the days of yorr, if you needed to make repairs to a sailing ship away from home, you might need to know the timbers limitations.

 

[Clevy]

Originally Posted By: bepperb
The Sagulator is what I use. To be honest there isn't a huge difference and I just assume everything the same. The only time I would think otherwise is with OSB/MDF/plywood which have considerably more sag.

http://www.woodbin.com/calcs/sagulator.htm

Anyway, I think you'll find that softwoods are at least 75% as rigid. No way a 1x3 oak is as strong as a 2x4 fir.



Osb is nothing like mdf and mdf is nothing like plywood.

And they will only sag if over-spanned.
Sheathing like osb is way stronger than any dimensional equivalent.

Your post is in every way wrong. Please save yourself the carpal tunnel and stick to what you know because wood isn't it.



I've got span tables for everything from 2x4 to 12x12 timbers in one of my old carpentry books however they are obsolete because today we use nothing but engineered materials for floors and roofs.

 

[JHZR2]

Originally Posted By: bepperb


Anyway, I think you'll find that softwoods are at least 75% as rigid. No way a 1x3 oak is as strong as a 2x4 fir.



The 1x3 vs 2x4 was just for conversation. If there is a rule of thumb like 75%, that would be interesting generally, however, it would also necessarily vary by species.

I also get it that an engineered laminate I beam or something like that will be better/stronger than dimensional lumber... But I was really just interested in wood vs wood.

It's useful for making tables and shelves and stuff like that, I suppose.

 

[expat]

The Grade (quality) of the lumber will also play a part.

You cannot just categorize lumber as Hard wood and Soft wood.
Douglas Fir is pretty darn hard and is Soft wood. Balsa is very Soft, but is a Hard wood.

Can I suggest this (U.S. Navy) book for you? I think you will find it very informative

http://www.amazon.ca/Construction-Techniques-Houses-Buildings-Explained/dp/0486202429

 

[bepperb]

Originally Posted By: Clevy
Originally Posted By: bepperb
The Sagulator is what I use. To be honest there isn't a huge difference and I just assume everything the same. The only time I would think otherwise is with OSB/MDF/plywood which have considerably more sag.

http://www.woodbin.com/calcs/sagulator.htm

Anyway, I think you'll find that softwoods are at least 75% as rigid. No way a 1x3 oak is as strong as a 2x4 fir.



Osb is nothing like mdf and mdf is nothing like plywood.

And they will only sag if over-spanned.
Sheathing like osb is way stronger than any dimensional equivalent.

Your post is in every way wrong. Please save yourself the carpal tunnel and stick to what you know because wood isn't it.



I've got span tables for everything from 2x4 to 12x12 timbers in one of my old carpentry books however they are obsolete because today we use nothing but engineered materials for floors and roofs.


My point was that I treat all wood the same, the exception would be for the odb/mdf/plywood where I do not. I'm not sure if I wrote it poorly, if you have poor reading comprehension, or if you were just too excited to win at the internet and couldn't help yourself.

Anyway, my purposes are furniture, not construction, and an MDF/osb shelf will sag considerably more than a solid lumber equivalent. And that's the only thing relevant to my work. But if someone took, say an Oak shelf and wanted it in paint grade poplar I wouldn't think twice about substituting in the same design.

I guess my advice to the OP would be that it might depend on the application and who you talk to.

Clevy, pop a Xanax and a baby aspirin and chill.