"A 'reasonable amount' of impact," the San Mateo County planning staff wrote, "is not possible to quantify." That line comes from the January 2026 staff report behind the County's new Design Review Ordinance, and it explains why the County deleted its standards on blocking private views and protecting privacy. Before, those standards let some impact through as long as it stayed reasonable. Now they appear only as recommendations that applicants may consider.
This matters most in Emerald Hills, where homes carry a Redwood City 94062 mailing address but sit in unincorporated San Mateo County, so County rules govern what gets built there. Since July 23, 2026, design review for a new home or addition in the Emerald Lake Hills district has been a staff-level pass/fail check with no public notice. For anyone paying for a view of the lake or the valley, the protection now comes from fixed numbers on the lot next door. No hearing decides it.
The Last House Decided the Old Way
The clearest picture of what changed is a case that started under the old rules and ended weeks after the new ones were adopted. It involved a planned 5,935-square-foot, two-story house with a 744-square-foot three-car garage on Jefferson Avenue. The new house would replace an existing home on a 21,979-square-foot parcel next to Upper Emerald Lake. The County file, PLN2025-00201, lays out the timeline:
- July 7, 2025: the application is received.
- October 16, 2025: the project is deemed complete.
- November 4, 2025: the Emerald Lake Hills Design Review Officer hears public comment on house size and placement, lake views and privacy, and recommends approval.
- November 26, 2025: the Director of Planning and Building issues the decision letter.
- December 11, 2025: an appeal goes to the Planning Commission.
- April 8, 2026: the Planning Commission upholds the approval, 3 to 0.
- April 23, 2026: a second appeal goes to the Board of Supervisors.
- August 11, 2026: the Board upholds the approval and adds conditions.
From application to final action took about 13 months. The project's approval never seriously changed. What changed was the details. The required privacy screening between the two lots went from 5-gallon plantings to 15-gallon evergreens that reach 20 to 25 feet when mature, and they have to be kept as separate trees outside the lake pathway easement. The County also recommended, but did not require, a clerestory window in the back second-floor bedroom.
That kind of negotiation, over tree size, window placement and screening height, is what the old hearings produced. It was also slow, and the timing of a public hearing was not in the owner's control.
What Replaced the Hearing on July 23
The Board of Supervisors adopted the updated Design Review Ordinance on June 23, 2026, and it took effect outside the Coastal Zone on July 23, 2026. The County's Emerald Lake Hills Design Review Officer page now says that hearings will be scheduled only as needed for projects submitted before that date.
Under the ministerial review process, a planner checks the project against the written standards. Staff decide the result, the County lists that decision as "not appealable," and if a project fails, the owner can apply for a minor or major design exception for an extra fee. The County estimates the process at 2 to 4 weeks and about $861.
The County's reason was state housing law. Staff described how the legislature, starting with ADUs in 2016 and then SB 9 and SB 35, limited local design review for those housing types to objective standards. In the words of the staff report:
"State law generally requires ministerial review of these qualifying housing projects, effectively prohibiting public comment periods, potential hearings, and appeals associated with discretionary review procedures."
The County applied objective standards across the board, so ADUs and SB 9 projects now meet design standards they had largely skipped before. A custom single-family home or second-story addition gets the same treatment, so neighbors have lost the hearing on those projects too. The staff report names Emerald Lake Hills and Oak Knoll Manor, Devonshire and Palomar Park as the Bayside districts where hearing-based review ended.
The Numbers That Now Protect a View
Because the hearing is gone, a view's protection comes from the measurable limits on the lots around it. The Jefferson Avenue staff report includes a table showing those limits for the RH/DR zone, next to what the approved house proposed:
| RH/DR standard | Required | Jefferson Avenue proposal |
|---|---|---|
| Maximum building height | 28 ft | 27 ft 10 in |
| Maximum floor area ratio | 30% | 29.86% |
| Maximum building site coverage | 25% | 22.76% |
| Minimum front setback | 20 ft | 21 ft 1 in |
| Minimum rear setback | 20 ft | 20 ft 2 in |
| Minimum side setback | 7.5 ft | 11 ft 3 in |
| Minimum combined side setbacks | 20 ft | 46 ft 5 in |
| Minimum lot size | 12,000 sq ft | 21,979 sq ft |
The approved house came within 2 inches of the height limit, within a fraction of a percent of the floor area limit, and within 2 inches of the rear setback. The process worked as designed. A house that meets every number gets approved, and after July 23 there is no hearing where a neighbor can ask for it to be smaller.
So for a buyer looking at a view home, the useful question is what the lot downhill or next door is allowed to hold under these limits. A one-story house on a large lot below you may have plenty of unused height and floor area left.
The new Design Review Standards in Section 8.256.180 also set rules that shape what goes up on a hillside. On steep Emerald Lake Hills sites, they limit raised building pads, how far a garage can be dug into a steep uphill lot, and excavation for flat yard areas. The main house color can't have a light reflectance value of 50% or higher, and the palette leans toward warm grays, beiges, natural wood and muted greens. Reflective materials are generally prohibited, and chain-link fences are not allowed in residential areas. Separately, the County's Protected Tree Ordinance protects trees 6 inches or more in diameter in Emerald Lake Hills and Oak Knoll RH/DR, and removing one requires a permit unless an exemption applies. Many of the trees that screen views and privacy here fall under that rule.
A Redwood City Address With County Rules
The same split between mailing address and governing agency applies to more than design review. Inside Redwood City limits, building permits go through the City's Building & Code Enforcement division. In Emerald Hills, they go through County Planning & Building. The Jefferson Avenue parcel shows how this plays out. Its water comes from the Redwood City Municipal Water Department, its sewer service from the County's Emerald Lake Sewer District, and its design review came from the County. The County routed that project to its Roads, Sewers, Drainage, Geotechnical and Parks reviewers and to the Woodside Fire Protection District.
There is a recurring cost tied to the County as well. The Emerald Lake Heights Sewer Maintenance District, formed November 4, 1947 and governed by the Board of Supervisors, serves this area. On the County's sewer service rate schedule, the Emerald Lake SMD charge is $1,995 per residential unit for FY 2026-27 and is scheduled to rise to $2,065 for FY 2027-28. Service depends on the parcel, and the County's sewer services page lets anyone check it by address. Roads vary too. The County's maintained-roads map shows which street segments it maintains. According to the County's right-of-way maintenance guide, a road the County has not accepted into its maintenance system stays the responsibility of private parties.
All of this sits within the same 94062 that covers Edgewood Park & Natural Preserve, 467 acres of County parkland, and the nine-hole par-3 Emerald Hills Golf Course on Wilmington Way.
Pricing a View in a Market Running Above List
Countywide reporting doesn't break out Emerald Hills. The closest current figures are citywide. According to SAMCAR's September 2026 sales report, Redwood City single-family homes sold in September 2026 at a median of $2,455,000 across 41 sales, averaging 21 days on market and 104% of list price.
When homes sell over asking, buyers have little time to research before writing an offer. A view premium gets priced at offer time, and the rules that limit a downhill lot are now fixed, published numbers that can be looked up. A seller can lay out a neighboring parcel's zoning envelope in the disclosure package, and a buyer can ask for it. For projects filed after July 23, the published standards decide the outcome.
Projects filed before July 23 can still go to legacy hearings. The County's 2026 calendar lists an Emerald Lake Hills Design Review hearing for December 1. Any neighboring project filed after that date gets a staff check against the numbers.
Frequently Asked Questions
Can I still appeal a neighbor's new house in Emerald Lake Hills? For projects reviewed under the ministerial process, the County describes the staff decision as not appealable. The code does allow an appeal to the Planning Commission of a decision on a minor design exception.
Did the County drop all view and privacy language? The standards that couldn't be measured were deleted as requirements and kept as recommendations for applicants to consider when designing a project.
Does the change affect ADUs and SB 9 projects? Yes. Applying objective design standards to ADUs and other housing that state law streamlines was one of the main reasons for the update.
This post is general information about published County rules and isn't legal, tax or financial advice. Confirm how any rule applies to a specific parcel with County Planning & Building and with your own attorney or other professional.
If you're weighing a view property in Emerald Hills or planning a sale where a neighboring lot's building limits affect your price, Dana Rae Stone can go through the County file, the zoning numbers and the disclosure package with you before you commit. Let's talk about your home.
