How close can a pool be to a house footing or a retaining wall in Pima County?
Verified against the primary source on .
No part of the pool structure may sit inside a 45 degree line drawn from the bottom of any footing. Pima County also requires pool equipment to sit at least 4 feet from a required barrier, which is more stringent than the ISPSC 305.2.10 clear zone of 36 inches.
Two Pima County requirements that are not in the base ISPSC text and that change where a pool can physically go on a lot.
THE 45 DEGREE RULE. No pool structure may fall inside a 45 degree line projected from the bottom of any footing. The purpose is straightforward: excavating a pool inside that line removes the soil wedge that the footing is bearing on, and the footing loses support. On a typical residential footing 18 to 24 inches below grade with an 8 foot deep pool, the rule pushes the pool substantially further from the house than a setback table would suggest. It applies to house footings, garage footings, casita footings and retaining wall footings alike.
What to do when the rule is violated by the desired layout. The answer is not to move the pool 2 feet and hope. It is either to move the pool out of the influence zone, or to underpin, or to design a structural solution and have the engineer show it. An Arizona PE seal is already required on every in-ground pool structural plan, so the engineer is already on the job.
THE 4 FOOT EQUIPMENT RULE. Pima County requires pool equipment to sit at least 4 feet from a required barrier. The base ISPSC clear zone at 305.2.10 is 36 inches. Pima’s figure is more stringent, and it exists for the obvious reason: equipment next to a barrier is a climbing aid. A pad sited at 36 inches because someone read the model code will fail inspection here.
Both rules were verified against Pima County’s own adopted 2024 ISPSC amendment exhibit on 2026-09-10, adopted at Pima County Code 15.04.020(A)(11) by Ordinance 2025-15.
A citation caution worth carrying. The codified 15.04.020(A)(11) calls the ISPSC amendment Exhibit K, while the published exhibit PDF and staff report P25TA00001 call it Exhibit J. Cite the ordinance number, not the exhibit letter.
Correction. Designs that site pool equipment at the ISPSC base 36 inch clear zone in Pima County, where the local figure is 4 feet.
Authority: Pima County Code 15.04.020(A)(11); Ord. 2025-15; 2024 ISPSC as amended, cf. base 305.2.10. Verified 2026-09-10. Evidence grade: VERIFIED. Read from the adopting ordinance or the published code section.