# dbl 2 x 6 post strength



## dproc (Mar 3, 2006)

Curious, how much vertical weight (as a post) can 2- 2 x6x7' SPF nailed together support


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## WBailey1041 (Jan 31, 2014)

dproc said:


> Curious, how much vertical weight (as a post) can 2- 2 x6x7' SPF nailed together support


Single column?
Two columns?
How high?
California code?
Ohio pole barn?
Miami-Dade?


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## Pounder (Nov 28, 2020)

WBailey1041 said:


> Single column?
> Two columns?
> How high?
> California code?
> ...


It's 2-2x6 nailed together. The height is 7'. It's not a code question, it's physics. He's looking for a dead load at failure.

Not to be a dick here, but all of the information was in his post.


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## G&Co. (Jul 29, 2020)

The height doesn't matter. If the column is perfectly straight and constrained so it can't bend/buckle, it's strictly a matter of the compressive strength of the wood. For softwoods it's in the range of 4500-7500 psi. You can look up the compressive strength of the specific species you're interested in.
In real life the post will likely buckle long before it's crushed in compression. Unless you encase it in a tight fitting steel tube.


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## DenverCountryBoy (Jan 10, 2021)

The correct answer is three fiddy


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## hdavis (Feb 14, 2012)

dproc said:


> Curious, how much vertical weight (as a post) can 2- 2 x6x7' SPF nailed together support


Unless nail or glue laminated, twice the weight of a single 2X6.


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## hdavis (Feb 14, 2012)

BTW, load at failure is not a constant when it comes to pieces of lumber. Some fail earlier, some fail later. Everything you'll find includes a safety factor to avoid failure, even the numbers for the basic wood properties used in the failure calculators. 

It also depends on the lumber grade, which isn't specified.

As a practical matter, I've had no fails using 2 nailed 2X4s SPF studs and 4 ton jacks in the 7' range, which would translate to no fails using 2X6 SPF 7' stud grade with ~ 6 ton jacks.


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## Redeyedfly (Sep 20, 2016)

G&Co. said:


> The height doesn't matter. If the column is perfectly straight and constrained so it can't bend/buckle, it's strictly a matter of the compressive strength of the wood. For softwoods it's in the range of 4500-7500 psi. You can look up the compressive strength of the specific species you're interested in.
> In real life the post will likely buckle long before it's crushed in compression. Unless you encase it in a tight fitting steel tube.


The height certainly matters There are no perfectly straight columns with continuous bracing. The capacity is reduced by the square of the unbraced length, so if the column is twice as high, it has 1/4 the capacity. 

ALL of the info was given in the OP except what type of load and bracing. Assuming a load duration of 1.0 (floors) a double 2x6 SPF 7' high braced on the narrow end (with sheathing/gyp presumably) has an ASD capacity of about 16kips but end bearing capacity will reduce that to 7kips. If it's a freestanding column about 4.5kips.


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