Lean in a porch or deck support post usually comes from either local wood decay at the post base or a footing/soil support problem that lets the post move — and the two have different signs and fixes. [5]
Work through these checks before you remove any post or start repairs:
Family Handyman’s homeowner inspection steps provide a practical walkthrough for checking rotten supports and measuring offsets. [8]
Wood-decaying fungi need elevated wood moisture to develop; they break down cellulose and lignin and produce soft, crumbly or stringy wood, so decay commonly starts where wood contacts soil or concrete or where water collects. [4]
A simple practical rot test is probing the post with a screwdriver; evidence of soft or spongy material at the base strongly points to rot as the primary cause. [4]
By contrast, settlement or footing bearing problems tend to affect multiple posts or an area and produce soil depressions, stair-step cracks in nearby masonry, or house movement symptoms such as doors and windows sticking. [5]
Never remove a load-bearing post without first installing temporary supports. [8]
Typical temporary shoring uses adjustable screw jacks or commercial jack posts with proper blocking/cribbing placed to carry the load while the failing post or footing is repaired or replaced; transfer loads gradually when installing the permanent element. [8]
For prescriptive deck and porch post repairs, use isolated concrete footings sized per code/guide tables, set corrosion-protected metal post bases on those footings, and install ground-contact–rated replacement posts or wrapped columns. [3][6]
The prescriptive approach favors isolated footings with metal post bases that keep wood elevated above concrete and soil to protect posts from moisture and ground contact; follow the AWC DCA6 tables and the referenced IRC deck provisions for footing sizing and detail requirements. [3][2]
Simpson Strong-Tie and similar manufacturers offer porch post bases (for example, the PPBZ line) designed to create a stable, durable connection and simplify staged construction; follow manufacturer installation guidance to avoid temporary-support failures during the work. [6]
A common repair sequence for a rotten or improperly supported post is: install temporary shoring, remove the failing post, provide an appropriately sized footing, set a corrosion-protected metal post base on the footing, and install a ground-contact–rated replacement post or column mounted to that base. [3][6][8]
If the cause is deeper bearing failure, expansive soils, or poor subgrade, replacing a single post and its shallow footing may not stop further movement; engineered underpinning such as helical piles or push piers is appropriate where footings cannot be made to bear on competent soil. [5][7][10]
Helical piles and other driven or torqued pier systems are established permanent solutions to support settled or undermined footings, and manufacturer/installer documentation shows use-cases where underpinning is needed instead of shallow footing repair. [7][10] See our deeper primer on helical piers & screw piles for more on sizing and contractor selection.
Exterior footings must be placed not less than 12 inches (305 mm) below the undisturbed ground surface and, where applicable, at or below the local frost depth per the IRC; frost depth requirements vary widely by region, so consult local code tables or authorities for the correct frost-protection depth in your area. [1]
For deck footings and post details use the AWC DCA6 prescriptive tables together with IRC R507 guidance for prescriptive deck construction and connections. [3][2]
Typical homeowner-oriented cost and planning resources cover post replacement and pier solutions, but specific prices vary by location and project scope and should be checked against current local estimates and contractor quotes rather than inferred from a single source. [9][10]
Do these porch or deck post issues apply to you?
Quick checkWork through these checks before you remove any post or start repairs:
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