• Definition of a Hillside Lot
• History and Initial Conditions
• What do you mean by “slope,"or “grade difference?"
• What do you mean by “graded area?"
• Process for Determining a Hillside Lot
• Where do I get a topographic map?
• How long does it take to find out whether I’ve got a hillside lot?
• How big can my house be?
• What are the outside grading limits?
• When do I call for a first inspection of my hillside residential property?
• What happens if I grade more than what was shown on my approved plans?
• What about retaining walls?
• Are there restrictions for fences and walls?
• Why do my neighbors have perimeter fences on their property line?
• What are the building height restrictions?
• Hillside Grading Waivers
• Hardship Considerations
• Do I go through this hillside determination/hillside grading waiver process myself?
• Where do I go to hire an engineer?
• Can I appeal any restrictions?
• Does someone have to check my property?
• What is the process for subdividing a hillside parcel?
• What plants can I use for re-vegetation?
Definition of a Hillside Lot
A lot is considered hillside when it has a slope of 10 percent or greater. This means that in 100 feet there is a difference of 10 feet or more of grade, as shown below:
History & Initial Conditions
The original hillside ordinance was passed in 1972. Grading that occurred before 1972 is “grandfathered,” meaning that it is considered existing grade. Where there is an existing structure, as long as no grading occurs beyond those areas graded in 1972, and the amount of earth moved is minimal, no additional grading plan is required. A plan should be submitted with the revisions, showing that all proposed disturbed areas are within the existing disturbed areas. This can be done on the site plan. However, the 30 feet building height restriction remains, which is 30 feet over “natural” grade (1972 grade) at any “slice” through the structure.
What do you mean by “slope," or “graded difference?"
“ Slope” (grade difference) is the amount of elevation change over a horizontal distance.
What do you mean by “graded area”?
“Graded area” is any area disturbed by construction (including utility services), or where your driveway, patios, pool, walkway, turf areas, planters, retaining walls, site cuts or fills, or backfill areas have disturbed or changed the natural ground. The disturbance within the public utility easement does not count as graded area, but should be re-vegetated.
Process for Determining a Hillside Lot
The city of Phoenix uses a system called “averaging slope”. This method works in the following manner: using a topographic map of the site, starting in the flattest portion, measure a 100 foot length (which may go as much as 50 feet off the site) following up or down the contours of the slope. Where there is 10 feet or more of slope difference in 100 feet, there exists a hillside situation. This analysis is performed by your engineer or architect, and reviewed by the city.
Where do I get a topographic map?
Central Records, located on the 3rd floor of City Hall, has topographic maps and quarter section maps for most areas north of South Mountain. You will need to hire a land surveyor for the areas where the city does not have topographic maps. Sometimes the developer will have topographic maps and topographic information for their subdivision.
How long does it take to find out whether I’ve got a hillside lot?
By overlaying the topographic map on the quarter section map, you can determine the extent of the slope on your lot. To do that, you would measure 100 feet down the slope and count how many feet of change there is. This procedure usually takes a few minutes, depending on one’s knowledge and experience. If you would like to have staff assistance, you may schedule an appointment with the city’s Landscape Architect at 602-262-7811.
How big can my house be?
Unless your zoning is more restrictive, twenty-five percent of the total square footage of the lot may be put “under roof,” which includes everything with a permanent roof over it (from a bird’s eye view), including covered patios and roof overhangs. If all of the 25 percent “under roof” is not used, it cannot be used or added to the graded area beyond the roofline. The 25 percent is a “use it or lose it” amount. However, it can be used in future additions to the building(s).
What are the outside grading limits?
Beyond the “under roof” limit, an additional 10 percent of the total hillside portion of the lot can be graded. This amount includes all grading for driveway, yard areas, parking, pool, planters, walkways, utility corridors, site cuts or fills, and any other disturbed areas on the lot used for any purpose. If the lot is planned residential development, your engineer or architect should check the site plan to determine if the 10 percent grading area is based on the entire parcel or on each individual lot. If the amount of proposed grading exceeds the 10 percent allowable limit, the owner may request an additional 5 percent from the city Manager’s Representative (CMR), who is currently the hillside reviewer. The additional 5 percent must be re-vegetated with natural Sonoran-type desert vegetation.
When do I call for a first inspection of my hillside residential property?
After purchase of the hillside grading (CHG ) and (CSL) permits, the construction fence must be installed as shown on the approved plan. After the fence is in place, an inspection must be requested to inspect the fence prior to starting any work. After the fence is approved, any salvageable trees and cactus should be moved to a holding spot for replanting at the re-vegetation stage of your project. A letter from the salvage company must be provided if any plant material is considered unsalvageable.
What happens if I grade more than what was shown on my approved plans?
This is a violation of city ordinance and city code. All work in that area must stop immediately and the construction fence must be reinstalled. The landscape/hillside section and your inspector are to be notified. Revised hillside plans showing how to mitigate the damage and additional vegetation must be submitted. Violations that go unreported may be subject to fines and will certainly experience project delays.
What about retaining walls?
No retaining wall may be over six feet in height over the footing. If more height is necessary, additional retaining wall(s) may be required. The added wall(s) must be one foot back for each additional foot in height. The distance between walls must be between four and six feet, and must be re-vegetated with screening desert plant material. This area is not included in the total graded area. However, retaining walls shall not be used to terrace or otherwise alter natural terrain, other than to fit the house into the site.
Are there restrictions for fences and walls?
Fences and walls may not be installed along the perimeter; but can be installed within any of the graded portions of the lot, since all areas within the fence/wall are considered graded, and thereby fall under the 10 percent allowable grading area. The maximum height of the fence/wall is six feet. Maximum combined height of the retaining wall plus any screen wall is nine feet. An example would be a three-foot retaining wall plus a six-foot screening wall.
Why do my neighbors have perimeter fences on their property line?
Effective January 1, 1994, the ordinance prohibits property line fences/walls on hillside lots. Many perimeter walls were built prior to 1994, and a few people have requested and received a zoning variance. Also, not all lots within subdivisions are hillside lots.
What are the building height restrictions?
The maximum height of a building is limited to 30 feet over the natural grade at any point throughout the building. This is not averaged across the floor of the building.
Hillside Grading Waivers
Even if the lot was subdivided before 1972, and even if the lot is under the 18,000 square foot minimum for a hillside lot, the lot is still hillside and must meet the hillside requirements. If the owner cannot meet those standards, the owner may apply for a hillside grading waiver, which will be reviewed by DSD staff and possibly approved. The cost of a grading waiver is determined by the current Fee Schedule, and if the result is appealed to the Design Advisory Board, there will be an additional fee.
Hardship Considerations
Staff will generally support a grading waiver to be considered by DSD if there is a hardship caused by the lot size, the hardship is not self-imposed, and the owner has made every effort to meet the intent of the hillside ordinance. Examples of typical hardships include:
• Undersize Lots—Lots with an area fewer than 18,000 square feet, subdivided prior to 1972, and possibly
annexed from the County.
• Lot Preservation—A lot with large rock outcroppings or significant natural features to preserve. This may
push the house farther back on the lot, causing additional grading.
• Natural Washes—The lot has one or more washes that may affect how a house can be
situated on the lot.
• Lot Layout—The flattest area on the lot might be to the rear of the lot causing a longer
driveway; or the lot is extremely narrow at the front, causing the house to be pushed
farther back.
• Lot Orientation—To reduce the cut and fill on the lot, the house has to be set farther
back from the street.
Typical items that are not considered hardships might include:
• The owner wants a large pool, entertainment, or turf area.
• Excessive drive, parking, or courtyard areas.
Do I go through this hillside determination/hillside grading waiver process myself?
The hillside review process requires hiring a licensed engineer to do the grading and drainage plans, which include hillside information and submission of plans to DSD’s Central Log-In section on the second floor of City Hall. Refer to the Hillside Checklist for requirements, but you will need five copies of the plan—two for the grading and drainage review, two for the hillside review, and one for field review. Check the Fee Schedule for the cost. The turnaround time for plan review is approximately two to four weeks, depending on the number of plans the city is currently scheduled to review.
Where do I go to hire an engineer?
We suggest the Yellow Pages or asking your architect to recommend a licensed engineer. city staff is not allowed to recommend any engineers.
Can I appeal any of these restrictions?
Yes. Building height, walls/fences, and the maximum area “under roof” can be appealed through the zoning variance process. Zoning variances may be applied for through the Zoning Division of the Planning Department at the Development Center on the second floor of City Hall.
Does someone have to check my property?
Yes. The Development Services Department checks your construction fence before grading. A construction fence is installed to protect the undisturbed areas of the site. We may check during construction to see that the fence remains up and the undisturbed area remains protected. Before a Certificate of Occupancy will be issued, you must call for a final inspection that will ensure all disturbed areas have been re-vegetated and the grading is consistent with the approved plan. Noncompliance can delay your move-in.
What is the process for subdividing a hillside parcel?
The following outlines the steps needed to process a hillside parcel subdivision:
1. Conduct a slope analysis to determine what part of the property is hillside.
2. Determine the maximum density of development you would be allowed.(See Zoning Ordinance 710 for instructions.)
3. Review and approval of slope lines
4. Site analysis mapping natural features, washes, plant materials
5. Pre-application or preliminary plan