Helical Pile Permits & Building Codes: IRC, IBC and AC358

Helical piles are allowed by U.S. building codes, but they are approved differently depending on the building. Commercial and larger projects fall under the International Building Code (IBC), which covers helical piles directly in Chapter 18. Houses, decks, and small structures fall under the International Residential Code (IRC), which does not prescribe helical piles, so they are accepted as an "approved" alternative, usually backed by an ICC-ES evaluation report under acceptance criteria AC358 or by an engineer's design. Local building departments adopt and amend these codes, so always confirm with yours.

Key takeaways

• IBC projects: design, capacity, installation, and special inspection of helical piles are covered in Sections 1810.3.1.5, 1810.3.3.1.9, 1810.4.11, and 1705.9.
• IRC projects: helical piles qualify as "other approved structural systems" for footings and deck supports, usually through an evaluation report or engineered design.
• AC358: the ICC-ES acceptance criteria that manufacturers test against to earn an evaluation report (ESR) for a helical pile system.
• Paperwork to expect: an ESR number or engineer's letter, a pile layout, target torque and minimum depth, and a torque log after installation.
• Canada: the National Building Code and provincial codes apply, and many residential screw piles carry CCMC evaluations.

Do you need a permit for helical piles?

In most cases, yes, because the piles are part of a foundation or deck that needs a permit anyway. The IRC exempts only small, low, detached decks, meaning 200 square feet or less, no more than 30 inches above grade, not attached to the house, and not serving a required exit door (IRC R105.2). New homes, additions, attached decks, and most foundation repair work typically require a permit. Some cities have their own rules for repair work, so ask before work starts.

What the IBC says about helical piles

The IBC treats helical piles as a type of deep foundation. The core sections are summarized below, based on the 2021 edition; numbering can shift between editions.

The torque correlation in 1810.3.3.1.9 is what makes helical piles practical to verify in the field. Capacity is estimated as Qult = Kt × T, where T is final installation torque and Kt is a factor tied to shaft size. Our article on how deep helical piles go walks through an example, and how much weight a helical pile can hold covers capacity.

Who does the special inspection?

On IBC projects, an independent special inspector watches installation and records the data required by Section 1705.9. The inspector checks the results against the approved geotechnical report and construction documents. The CHANCE evaluation report ESR-2794 adds that the inspector should verify the manufacturer and the installer's certification.

How helical piles are approved under the IRC

The IRC's footing rules list concrete, masonry, crushed stone, and wood foundations, then add "other approved structural systems" that can carry the loads and transmit them to the soil (IRC R403.1). Deck footings use the same phrase: decks must sit on "concrete footings or other approved structural systems" (IRC R507.3). The IRC's alternative materials section lets the building official approve such systems based on valid research reports from approved sources (IRC R104.11, 2021 edition).

In practice, residential approval usually comes through one of two routes:

1. An ICC-ES evaluation report. ESR-2794, for example, allows CHANCE helical piles under the IRC as an alternate foundation system for light-frame construction, porch decks, elevated walkways, stairways, and accessory structures. It lets a geotechnical investigation be skipped for these structures if capacity is based on torque with a safety factor of 2.5, and it states that continuous special inspection is not required under the IRC (Hubbell).
2. An engineer's letter or stamped design. A licensed engineer specifies the pile, the load, the target torque, the minimum depth, and the connection. Many building departments require this even when an ESR exists, especially for additions, heavy loads, or foundation repair.

What is ICC-ES AC358?

AC358 is the ICC Evaluation Service's Acceptance Criteria for Helical Pile Systems and Devices. It spells out the testing, calculations, and quality control a manufacturer must provide to receive an evaluation service report (ESR). Load tests verify the manufacturer's torque correlation, and the resulting report publishes capacities for shafts, helix plates, brackets, and soil.

An ESR matters because it gives a building official a third-party basis for approval without re-reviewing the product from scratch. When an installer tells you a system is "ICC-ES approved," ask for the ESR number and check that the specific pile model and bracket being used are listed in it. The report also sets conditions of use, such as installer certification, minimum spacing, and minimum embedment, that the job has to follow.

What documents does a helical pile permit need?

Treat this table as a starting point. Local amendments, state codes, and individual plan reviewers vary a great deal, and some jurisdictions publish their own helical pile policies. A few large cities also maintain their own building codes.

What happens at a helical pile inspection?

For residential work, an inspector may visit during installation or review the torque log afterward. They typically confirm the pile model, count and locations, the final torque and depth for each pile, and the post or bracket connection. For foundation repair, they may check bracket attachment before backfill. Keep a copy of the torque log and the final inspection sign-off; they are useful at resale and for warranty claims, as covered in our guide to helical piers for foundation repair.

Helical pile codes in Canada

Canada uses the National Building Code of Canada (NBC) as a model, and provinces adopt their own versions, such as the Ontario Building Code, the Alberta Building Code, and Quebec's Construction Code. Residential screw piles are commonly supported by evaluations from the Canadian Construction Materials Centre (CCMC). For example, CCMC 13691-R covers helical screw piles for single-storey homes and accessory buildings such as sheds, sunrooms, and decks under Part 9. It requires piles to be installed below the frost line by manufacturer-certified installers, with a professional engineer determining pile quantity, spacing, and allowable loads. Larger buildings are designed by engineers under Part 4.

How to avoid permit problems

• Call your building department before hiring and ask what they need for helical piles.
• Choose a system with a current ESR or CCMC evaluation that lists the exact components being used.
• Confirm who pulls the permit and who provides the engineer's letter, and whether that is in the quote. Our helical pier cost guide lists common add-ons.
• Ask for a torque and depth log for every pile.

Experienced installers know what local departments expect. Find one through the Helical Pile USA directory by state, for example in New York, California, or Massachusetts. For project-specific rules, see our guides to helical piles for decks and helical anchors vs. helical piles. Installers, engineers, and manufacturers can get featured on Helical Pile USA.

Frequently asked questions

Are helical piles approved by the building code?

Yes. The IBC addresses helical piles directly in Chapter 18, and the IRC accepts them as "other approved structural systems," typically based on an ICC-ES evaluation report or an engineer's design.

What is an ICC-ES evaluation report for helical piles?

It is a third-party report, issued under acceptance criteria AC358, that confirms a manufacturer's helical pile system meets code and publishes its capacities and conditions of use.

Do helical piles need an engineer's letter?

For IBC projects, yes. For residential work it depends on the jurisdiction. Many building departments ask for a letter or stamped detail even when the system has an evaluation report.

Do helical piles require special inspection?

Under the IBC, continuous special inspection is required during installation (Section 1705.9). Under the IRC, reports such as ESR-2794 state it is not required, though local inspectors still review the work.

Are helical piles allowed in Canada?

Yes. Provinces adopt versions of the National Building Code, and many residential screw piles carry CCMC evaluations for Part 9 buildings. Larger projects are designed by an engineer under Part 4.