Fence Rules in Portola Valley

The town's Planning FAQs state: "A building permit is not required to build any fence 6' or less in height. However, when a fence, regardless of height, is to be built within your property's building setbacks, on your property line, or adjacent to a trail easement, a fence permit is required."

The municipal code requires a fence permit for construction of all fences built within required yards (§ 18.43.080(A)). The town's fence permit application lists what the zoning review checks, location, height and opacity among them.

The fence chapter answers both by zoning district and by yard.

Where (§ 18.43.020(A)):

• In districts with a minimum parcel area of less than one acre, domestic fences and fences that meet the horse-fence standards are allowed in required yards, including along property lines.
• In districts with a minimum parcel area of one acre, domestic fences and horse fences are allowed in required yards, but a domestic fence in a front yard must be set back at least 25 feet from the front property line.
• In districts with a minimum parcel area of two acres or more, only horse fences are allowed in required yards, including along property lines.
• In districts with a minimum parcel area of one acre or more, fences in required yards are allowed only on slopes of 20 percent or less.
• Along riparian corridors, fences must be set back at least 20 feet from the top of a creek bank; the top of the bank is determined case by case by town planning staff or the ASCC (§ 18.43.020(A)(5)).
• Double fencing — two or more parallel fences — must be located within the building envelope of a parcel.

How tall (§ 18.43.030(B)):

• 4 feet in front yards, 6 feet in side and rear yards, and 4 feet in side yards along road rights-of-way.
• Horse fences: 4 feet.
• Fences adjacent to public trails and paths in districts with a minimum parcel area of one acre or more: 4 feet.

In required yards, fences no more than 2 feet in height and no more than 20 feet in total length are exempt from the permit section, but still have to meet the chapter's other provisions except the opacity limit (§ 18.43.080(B)).

The code sets a threshold: "When a portion of a fence exceeding twenty-five percent of the total length of fencing within required yards on a property is damaged or voluntarily removed, any replacement fencing of that portion shall conform to the fence regulations pursuant to a fence permit" (§ 18.43.080(D)). A storm that takes down a long run of an older fence can turn a repair into a fence that has to meet today's code.

The code defines it by construction (§ 18.43.060): no more than three horizontal wood members, each no more than 6 inches wide, or no more than four horizontal wood or wire members; posts no more than 6 by 6 inches in cross section, no more than 4 feet high and no closer than 5 feet apart; 6-inch by 6-inch wire mesh may be attached, no higher than the fence; opacity no more than 50 percent; height no more than 4 feet.

The town's Conservation Committee has proposed amendments to the fence chapter, including wildlife-friendly fencing. As of October 4, 2026, they are proposed, not adopted. The limits by parcel size above — horse fences only in required yards where the minimum parcel is two acres or more — are not part of that proposal: they are in the code now (§ 18.43.020).

The town's planning staff confirm what applies at a specific address. For fence work in Portola Valley, photos of the fence are enough for the independent contractor assigned to your area to say what the repair involves. Rules for neighbouring towns are in the fence rules and permits guide.