Building a home in Clyde Hill
Clyde Hill's 25-foot height limit: what it means for your home
Clyde Hill limits a principal home to 25 feet above original grade at every point. The important part is not just the number: original grade refers to the ground when the City incorporated in March 1953. That can make a big difference on a sloped or previously graded lot.
On this page6 sections
Official starting point: Clyde Hill R-1 rules (Chapter 17.16). Verify the current code and parcel-specific rules before fixing a design.
Today's ground level may not be the starting point
Clyde Hill's definition of original grade looks back to March 1953. The public works director determines that grade using evidence such as surveys, plats, and information from a soils engineer. A new topographic survey shows current conditions, but it may not establish historic conditions on its own.
The City says many homes built after incorporation already have an original-grade determination. Start by asking City Hall for that record at cityhall@clydehill.org. If no accepted record exists, follow the City's determination process before assuming a roof elevation.
Height is checked at each point, not from an average
The R-1 limit is 25 feet vertically above original grade at the point being measured. It is not a citywide average-grade calculation or a measurement only at the front door.
For example, where original grade has an elevation of 100 feet, the ordinary height limit is elevation 125 feet. Where original grade drops to 93 feet, it is 118 feet at that point. Those elevations are an illustration, not a survey of your lot, but they show why one roof level may work uphill and fail downhill.
Two stories can work, but the section has to prove it
Two floors, the floor structure between them, ceiling heights, and the roof all need to fit. Tall ceilings and a steep roof pitch use height quickly. A daylight basement on a slope can make the downhill portion harder to fit, even if the house looks like two stories from the street.
Have the architect test a few sections early: through the highest roof point, the downhill rooms, the garage, and any tall stair or living-room space. Stepping the house with the land or changing roof form may work better than forcing a flat-lot design onto a hill.
Adding fill does not raise original grade, and digging down does not create a new legal reference level. Evaluate grading, foundations, retaining walls, and drainage together with the height design.
Chimneys and small accessory structures have separate rules
The R-1 chapter allows limited exceptions for chimneys and small dish antennas, which may extend no more than five feet above any part of the building. Do not treat that as another five feet for the roof, a room, or a large architectural enclosure; have the City confirm the actual feature.
Accessory structures generally have a 12-foot limit and separate area and placement rules. An ADU is a different project type with its own rules, so a generic accessory-structure limit is not an ADU design approval.
Check setbacks and private restrictions at the same time
On lots smaller than 15,000 square feet, the side-yard rules include an additional angled limit on the upper building. A second floor can meet 25 feet overall and still need to move inward from the side boundary.
Recorded covenants or view easements can impose additional restrictions. City approval does not override those private obligations, and the City's tree-view dispute process is not a general right to prevent a code-compliant neighboring house.
Practical worksheet
Put this guide to work
Worksheet updated . This is a planning example. Regulatory sources and data have their own dates.
Ask for a height drawing that can be checked
An illustrative roof elevation of 130 feet is 28 feet above a controlling grade elevation of 102 feet. Whether that complies depends on the applicable local limit and the legal grade-measurement method. Raising the finished yard does not automatically raise the allowed roof.
- Identify the rule
- Write the zone, overlay, applicable height row, grade definition, roof measurement and any separate wall or facade limit.
- Show the inputs
- Use the survey datum and labeled measurement points. Show existing or original grade and proposed finished grade separately, with roof elevations and sections on the downhill side.
- Test design changes
- Recalculate after changing the footprint, floor elevations, roof form or grading. Check chimneys, equipment and other features under their own rules.
- Leave a verification path
- Ask what survey certification or field check is required, at what stage and who will arrange it.
The useful deliverable is a calculation tied to a plan and survey, not ‘two stories are allowed.’ If the concept uses an exception or bonus, show both the base-compliant option and the conditions required for the alternative.
Action plan
What to do next
- 1
Request the property's accepted original-grade record before ordering duplicate work.
- 2
Have a surveyor and architect reconcile current topography with the City's grade determination.
- 3
Test ceiling heights, roof shape, and downhill sections before finalizing the floor plan.
- 4
Show original grade, proposed grade, roof elevations, and the 25-foot dimensions on the permit drawings.
- 5
Preserve surveys, photos, and grade records before demolition or earthwork.
Official resources