Coupling Treated and Non-treated Posts

[EquineTwo]

Howdy, I'll be starting a 24x36 simple gable structure soon. For the posts, I had initially planned to buy one single treated post for each (6"x6"), but am now considering just the treated portion for the 4' in ground plus another 4' above ground (8') and then stacking an untreated post (also 6"x6") on top of it for a 12" above around post. Any advice here or if it's even doable?
Thanks!

 

[manwithtools]

Not a good idea to begin with and more work than it would be worth by any measure, even if it was a good idea. What is your motivation for this?

 

[EquineTwo]

Thanks for your response. A few motivations...
1. If I decide to go a little higher than 12', it's hard to find 6x6s longer than 16'. So if I need to take the middle posts higher to reach the higher parts of the rafters, "coupling" posts would be a way to get them taller. How else to people do this?
2. Cost. Might save a bit...
3. Untreated wood where treated not necessary.

What do you think?

 

[egdede]

If you can't buy long 6X6's either use column mount poles:

https://polebarnsdirect.com/options/foundation-options/

or laminate 3 long 2x6's to make a column.

 

[GTFiero]

You can order 6x6 22’-26’ long post. Will save a ton of labor and time. Either way you do it you still need to set and brace post till the upper frame is attached. We have a 12’ wall with post set 54” below grade using 6x6, no regrets. Using trusses, if I remember correctly our longest post was 22’. The post we used were a fairly high grade of treated post, no warping or other issues with them, all very true.

The building is the avitar. 12’ walls with 10x10’ and 10x 18’ doors, 5/12 roof.

Really believe coupling the post just adds a weak point to the post.

 

[manwithtools]

If you can't buy long 6X6's either use column mount poles:

https://polebarnsdirect.com/options/foundation-options/

or laminate 3 long 2x6's to make a column.

Yep, Perma-Columns are a god option for OP's situation. Tripled up 2x6 is an option as well. You can combine shorter lengths and overlap the joints to create a strong post

 

[Shootinok]

I struggled with this when I built mine. I decided I really didn’t want to put the posts in the ground at all, and the permacolumns are expensive.
Having more energy than money, I decided to make my own version of the permacolumn.
I made plates to bolt my columns to and embedded them in 4’ piers I poured with the slab. Then built laminated posts with triple 2x6.

 

[Shootinok]

To answer your original question: I don’t see any reason what you’re proposing wouldn’t work.
Just stagger the joints, perhaps making the center one the tallest. It wold be no different than splicing the 2Xs for a taller post.


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[manwithtools]

To answer your original question: I don’t see any reason what you’re proposing wouldn’t work.
Just stagger the joints, perhaps making the center one the tallest. It wold be no different than splicing the 2Xs for a taller post.


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Not to be argumentative, but how would you propose to splice two 6x6's together in a manner that provides the stiffness that a pole type structure requires? Any joining method that I can think of is going to take quite bit of work and even then it's going to create a "hinge" point.

I can't see it being worth the effort if you can use other methods to get the end result desired.

 

[crasher98]

Not to be argumentative, but how would you propose to splice two 6x6's together in a manner that provides the stiffness that a pole type structure requires? Any joining method that I can think of is going to take quite bit of work and even then it's going to create a "hinge" point.

I can't see it being worth the effort if you can use other methods to get the end result desired.

There are a lot of multi-story back porches in Chicago that are made out of notched- and bolted-together 6x6's. Looks a little harrowing, but they - well, let's say they hardly ever collapse, and it usually takes a big drunken party to do it....

But thinking about it a little more, the porches do have horizontal members that help brace the vertical ones, so the back porch example isn't really germane to the question. Never mind!

 

[Shootinok]

Not to be argumentative, but how would you propose to splice two 6x6's together in a manner that provides the stiffness that a pole type structure requires? Any joining method that I can think of is going to take quite bit of work and even then it's going to create a "hinge" point.



I can't see it being worth the effort if you can use other methods to get the end result desired.

This is an acceptable method of construction in post framed buildings.

Properly joined, a built up 6x6 will be stronger than an equivalent sized timber.

https://www.anthonyforest.com/assets/pdf/apa/glulam/Post_Frame.pdf
See pages 5 & 6


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[manwithtools]

This is an acceptable method of construction in post framed buildings.

Properly joined, a built up 6x6 will be stronger than an equivalent sized timber.

https://www.anthonyforest.com/assets/pdf/apa/glulam/Post_Frame.pdf
See pages 5 & 6


Sent from my iPad

I agree with that method and suggested it earlier. Your link says nothing about splicing 6x6's together to form a longer post. That was the original question. I stand by what I said, the effort to join 6x6's together end to end is not a viable alternative as it's inferior to a post made of 2x's laminated in layers.

We seem to be agreeing here. Seems to be semantics involved in the discussion.

 

[Shootinok]

Ah.. it does indeed. You are correct.
Another example of wrapping my head around an idea and not seeing it succinctly as it was written.

I rescind my response that it would work as proposed and do NOT support the idea of joining single pieces of dimensional lumber in that way.
Laminated members to form a 6x6 - Yes, which is what my mind grabbed and wouldn’t let go [emoji846]

 

[manwithtools]

Ah.. it does indeed. You are correct.
Another example of wrapping my head around an idea and not seeing it succinctly as it was written.

I rescind my response that it would work as proposed and do NOT support the idea of joining single pieces of dimensional lumber in that way.
Laminated members to form a 6x6 - Yes, which is what my mind grabbed and wouldn’t let go [emoji846]

Thanks for the conformation, I thought that might be the case. Easy to do...

 

[EquineTwo]

Thanks for the input here. I think I will go the laminated post route. With treated the bottom 8 or so feet and untreated the rest of the way up. Thanks again.

 

[manwithtools]

Thanks for the input here. I think I will go the laminated post route. With treated the bottom 8 or so feet and untreated the rest of the way up. Thanks again.

Make sure that you get "ground contact" rated treated lumber. I would look for the local commercial lumber supply house or maybe a Farmers CO-OP if you have it.

 

[Firebrick43]

There are a lot of multi-story back porches in Chicago that are made out of notched- and bolted-together 6x6's. Looks a little harrowing, but they - well, let's say they hardly ever collapse, and it usually takes a big drunken party to do it....

But thinking about it a little more, the porches do have horizontal members that help brace the vertical ones, so the back porch example isn't really germane to the question. Never mind!

A porch takes mostly only vertical loads and is no way related to a pole building where the poles take shear loads from high winds. That is why joining two 2x6 without some serious steel splicing plates is a bad idea.


Also Shootinok method is a really bad idea in areas it freezes and with areas that have expansive clay. The post, in any pole building, should not be coupled to the poles. Freezing and wet soils will lift the slab slightly and if coupled to the poles will lift them to. Wet fines will flow under the bottom of the poles and over years of doing this will jack the building out of the ground, cause the slab to crack and settle unevenly. I have seen several shops with concrete poured around the post without a thing foam or visqueen break. The only way this should be done if there is significant compacted washed stone(12"+) and foam under the floor and foam wings or foam going 3' down around the perimeter to keep the frost from creeping under. Basically a shallow frost protected foundation.

 

[txvwnut]

The only way I could see adding length to a 6x6 would be to use a mortise and tenon type joint but I feel the tenon would need to be rather long for it to offer decent strength and support.

 

[manwithtools]

Firebrick, I just can't agree with your assessment in this instance. What Shootinok has is essentially a floating slab with piers, pretty typical construction for a red iron building for instance. Actullay for any building with point loads.

In his case the rebar tied into the slab and piers is going to insure they move as a unit for the most part. The poles are entirely above grade, mounted to piers that are part of the slab. I've seen hundreds of buildings constructed this way in frost prone areas and not seen any issue.

 

[Firebrick43]

Firebrick, I just can't agree with your assessment in this instance. What Shootinok has is essentially a floating slab with piers, pretty typical construction for a red iron building for instance. Actullay for any building with point loads.

In his case the rebar tied into the slab and piers is going to insure they move as a unit for the most part. The poles are entirely above grade, mounted to piers that are part of the slab. I've seen hundreds of buildings constructed this way in frost prone areas and not seen any issue.

Frost prone as in freeze to 24" Plus?

The OP doesn't list location which is why I pointed it out.

No large unitized foundation will survive if it freezes under the edges lifting it. It will collapse under it own weight. I guess I shouldn't say no foundation as I guess someone could design and build one with heavy enough reinforcement and large enough grade beams to survive but it would be ****** expensive.

What shootinOK is similar to a floating slab but it is not apparent if the rebar extends throughout the slab nor does it have a thickened edge or insulation under/aside it.

If the post or pier as your calling it were decoupled and poured below the freeze line there would be no issue.

Devils in the details

 

[Dustball]

Sounds like you're trying to make a Perma-Straight laminated column.