Residential Services
Five of the custom homes in E-Project's portfolio are contemporary hillside residences — Troon North, Desert Highlands Lot 361, Garmo, Wing and the two Kent houses. Hillside work is a distinct discipline: the ordinance decides how much of the lot you may disturb, and the design has to be good inside that number.
On a hillside parcel in the Valley, three numbers govern before anything else: how much of the lot you may disturb, how tall you may build measured from natural grade, and how deep a cut you may make. Get those from the ordinance first and the house designs itself around them. Get them last and you redesign.
Jurisdiction by Jurisdiction
An overlay, not a hillside district. It covers roughly 134 square miles north and east of the Central Arizona Project canal, and superseded the older Hillside Ordinance. The governing requirement is Natural Area Open Space (NAOS): a percentage of the parcel must be dedicated as undisturbed natural area, set by landform and slope.
Source: City of Scottsdale — Environmentally Sensitive Lands
Applies to all land in the mapped Hillside Development Area and to any land where natural terrain under the building pad slopes 10% or more — mapped or not. Review runs through the Hillside Building Committee, and a pre-application review is mandatory for every hillside application before a permit application.
Source: Town of Paradise Valley — Hillside Building Committee
Triggered where natural terrain on any lot or portion of a lot has a slope of 10% or greater, in all zoning districts. Density is capped by slope band, from 1.80 dwelling units per gross acre at 10–14.9% slope down to 0.20 per acre above 35%.
Source: Phoenix Zoning Ordinance §710
Ordinances change. These figures are cited from each jurisdiction's published materials as of 2026 and are given to show how differently the three regimes work — E-Project verifies the current standards against your specific parcel at the start of every hillside project.
Design Approach
Before massing, we map slope bands across the parcel and calculate the allowable disturbance or NAOS obligation. That produces a buildable pad envelope — usually much smaller and differently shaped than the owner expects — and every subsequent decision happens inside it.
Level changes that follow the landform cost less in retaining and cut than a single flat pad, and they read better from below. On a plane-based height limit like Paradise Valley's, stepping is also the only way to get volume without breaching the plane.
Access is frequently the constraint that kills a scheme. Grade limits, width minimums, surface restrictions and how the driveway counts against the disturbance allowance all need resolving before the house is designed, not after.
Hillside drainage is a design problem — where water goes, what it does to the neighbor downhill, and what the engineer will need to seal. Several jurisdictions require an engineer-sealed grading and drainage plan at thresholds far below what owners assume.
Hillside ordinances are, at bottom, view-shed ordinances. Materials, colour, reflectivity, exterior lighting and wall lengths are all reviewed for visual impact. Designing to that from the beginning is cheaper than defending it at a committee hearing.
The house is rarely the expensive part on a steep lot. We reconcile site work — cut, fill, retaining, driveway, utilities — into the construction budget at schematic design, when it can still change the scheme.
Built Hillside Work
| Project | Size | Status |
|---|---|---|
| Troon North Residence — Scottsdale | 6,500 SF | 2020 |
| Garmo Residence | 6,500 SF | In construction |
| Kent Residence 1 | 4,800 SF | 2018 |
| Kent Residence 2 | 4,800 SF | 2018 |
| Wing Residence | 4,100 SF | 2021 |
| Desert Highlands Lot 361 — Scottsdale | 3,800 SF | 2021 |
It depends on the jurisdiction, and the thresholds are specific. The City of Phoenix applies its Hillside Development standards where natural terrain on any lot or portion of a lot has a slope of 10 percent or greater, in all zoning districts. Paradise Valley applies Article XXII Hillside Development Regulations to all land in the mapped Hillside Development Area and to any land where natural terrain under the building pad slopes 10 percent or more, whether mapped or not. Scottsdale instead uses an Environmentally Sensitive Lands Overlay covering roughly 134 square miles north and east of the CAP canal, with requirements keyed to landform and slope.
Far less than the lot area suggests, and the calculation is written into the ordinance. Scottsdale's ESLO requires a percentage of the parcel be dedicated as Natural Area Open Space based on landform and slope — on Hillside landform this ranges from 50 percent at gentle slopes up to 80 percent above 25 percent slope. Paradise Valley's Article XXII sets allowable Disturbed Area by building-site slope, dropping from 60 percent at a 10 percent slope to about 13 percent at 25 percent and 10 percent at 40 percent. Phoenix caps lot coverage at 25 percent where slopes exceed 10 percent. This is why hillside design starts with the disturbance budget, not the floor plan.
Lower than you would expect, and measured differently. Scottsdale's ESLO design standard limits building height in single-family residential districts to 24 feet measured from natural grade — stricter than the 30-foot base district limit. Paradise Valley limits the primary building to a 24-foot plane paralleling pre-development natural grade, accessory structures to a 16-foot plane, and sets an overall 40-foot maximum from the highest point of the structure to the lowest natural grade. The shift from a flat height limit to a plane following natural grade is the single biggest surprise for owners coming from flat-lot experience.
In Paradise Valley, yes. Hillside applications go to the Hillside Building Committee, and a pre-application review is mandatory for all hillside applications before one of several review tracks is assigned. The Town's own guidance is that hillside committee review happens prior to applying for a permit. Small work may qualify for an administrative Hillside Chair review if it does not increase the footprint by more than 100 square feet, create more than 100 square feet of additional disturbed area, increase wall length by more than 15 linear feet, or exceed the main residence height. In Phoenix, hillside status also removes eligibility for both the Self-Certification program and Priority Expedited Plan Review.
Usually yes, and the cost sits in site work and structure rather than finishes. Cuts, retaining, driveway grade, drainage, and foundation systems stepping down a slope all add cost, and ordinances limit how much you can regrade your way out of the problem — Paradise Valley caps cut height at 30 feet and prohibits asphalt driveways, with a 30 percent maximum driveway grade. The design response is to work with the landform rather than flatten it, which is also what the ordinances are written to produce.
Have the disturbance budget and height plane checked before you close. It is the cheapest hour in the whole project.
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