Post Foundation System

pole barn post foundation

One of the most important decisions you can make to protect your investment is often overlooked these days.

A post frame building is supported by the posts rather than sitting on a concrete slab. For this reason uplift protection and settling protection is important to make sure your perfectly straight project stays that way.

Since we know how important uplift and settling issues are, each of our pole barn kits are designed using these guidelines:

• Size post based upon building span, post spacing, wind speed, and snow load.
• Only supply UC4B treated foundation posts.
• Size the concrete footer to ensure the building will never settle.
• Include uplift protection to ensure the building doesn’t rack under high winds.

Pole Barn Foundation Post Treatment
Your treated lumber will come with a treatment tag that indicates the level of treatment applied to the lumber in the treatment tank. A typical 4×6 or 6×6 at many lumber yards are treated to UC4A specification, like a fence post. A UC4B treatment is required for foundation wood and although it costs a little more it is well worth it.

An extreme condition treatment (UC4C) is available for applications indicating extreme duty requirements. The up-charge from our standard UC4B treatment to UC4C is a minor cost.

Gable End Posts
Our building packages include full height gable posts for substantial improvement in building strength and construction simplicity. The floor plan drawing indicates the location of each length post with post orientation included for 4×6 and laminated posts.

Post Embedment Techniques
Square Up A Pole Barn


  • I really appreciate all the information you provide.

    I’m a DIY and am tossing and turning about whether to backfill my post holes (set on 22″x11″ concrete footings) with concrete or with crush and run. You say you don’t recommend concrete. Can I trouble you please to comment on the advantages of using stone fill?

    Thank you very much!

    • admin

      Hi, concrete backfill is used in high wind zone conditions. Cost and poor drainage (once the concrete cracks around the post) are the only bad things I know about concrete.

      A sand/gravel backfill that packs easily provides three benefits. 1) no dirt touching the post 2) good drainage 3) better bearing capacity than soil so lateral resistance to the wind is better than dirt (but not concrete)

      Permacolumn has alternative products that our engineer recommends and likes. They have dry set and wet set brackets for existing slabs and concrete piers for augered holes.

      All of this is more expensive than embedding posts in the ground. If the posts you are purchasing have a 50 year rot warranty and you use a sand/gravel backfill that is the cheapest upgrade to a standard dirt backfill, and very effective too.

      If the post is treated UC4B (meaning like a foundation post) not UC4A (like a big box store 6×6) then rot is less likely to be a problem. Some areas have highly acidic soil and would be a good candidate for an alternative backfill. If you have an application near the coast and are below the water table that would be another, so it just depends on your situation and budget.

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