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Tonerboy
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# Posted: 7 Aug 2025 12:27pm
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Ok, here's my thinking I'm going to make the base frame (beams) out of 3-2x8 so I want a post that supports all 3 boards. A treated 8x8 post runs $40-50ft depending on length. 24 5ft posts will be $950-1,200. a built-up 8x8 post of 2x8 runs about $15, so 24 would be $360 which is a HUGH savings.
Let's talk about why I shouldn't do this. Posts will be set 36in deep in an 8in hole
This is for a 16x24 "stoney type" small house
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MtnDon
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# Posted: 7 Aug 2025 05:39pm - Edited by: MtnDon
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When beams are built up, they are positioned 'upright', resting on the edge of the 2x. So a beam made of three 2x8 is 4.5" wide and 7-1/4 inches tall.
No need for 8x8 piers, unless I don't understand your plan.
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gcrank1
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# Posted: 7 Aug 2025 06:36pm - Edited by: gcrank1
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I strongly recommend Not doing wood piers to avoid problems in the future. A structure of 16x24 is very heavy. Trying to fix problems beneath later is not something to take lightly, we've had more than a few inquiries here on how to fix failed piers to save a cabin.
Remember that you build from the bottom up and just adequate is not as good as overkill down there. If you dont get it right down there the rest up top is kind of a waste of time and money.
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DRP
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# Posted: 7 Aug 2025 06:38pm - Edited by: DRP
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Whoops, I see others have chimed in, well, more grist for the mill,
Why an 8x8 if it is only supporting 4.5" of beam width?
Engineering wise, for the code ref info go to awc.org>standards> NDS and NDS commentary, Built up columns is 15.3 and after. Basic columns are in chapter 3. Can you do it, yes, nails on 6" spacing or closer, probably at least 2 rows.
Your foundation idea is, uhh politely, needing help. Design wise, with napkin numbers there's probably about 20 tons on top of those spindly legs, how are you bracing that?
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Grizzlyman
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# Posted: 7 Aug 2025 07:42pm
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I would imagine it’s probably fine for compressive force only but that’s not the reality. for any rotational or shear forces the smalller 2x8 would not transfer the load evenly between them and if the connections fail then the boards would want to slide over each other. Or could twist and individual boards could crack and then there goes all the strength.
Here’s what Google says:
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Disadvantages:
Lower strength compared to solid posts in the strong axis: Built-up posts typically have a reduced strength compared to solid posts of the same material and dimensions.
Requires proper construction: The connections between the individual pieces of a built-up post must be carefully designed and installed to ensure adequate strength and stability.
Potential for slip: In mechanically laminated built-up posts, there can be slip between the layers under load, which can reduce strength.
Key Considerations:
Load requirements:
Solid posts are generally preferred for applications with high compressive loads.
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You could use 6x6s posts and not need to do 8x8 and that should lower your costs.
Solid posts seem like a relatively cheap insurance policy IMO
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