Before you hire a Lake Forest Park or Kenmore architect, know this: the city’s rules decide how much house your lot can take before anyone draws a line: yards, height, how much of the lot roofs and pavement may cover, and what trees, slopes and Lake Washington add on top. The two cities use different numbers, so I treat them one at a time. I design remodels, additions and new houses, and I administer the construction; I do not build. My first basic feasibility check is free and very quick, usually about a day. An in depth analysis goes further than the first check.
Key takeaways
- Lake Forest Park’s single-family zones stop at 30 feet, with roofs capped at 25 to 35 percent of the lot and hard surface at 35 to 45 percent.
- Kenmore’s R-4 and R-6 table allows 35 feet and has no coverage or floor area row; impervious surface is the limit, 45 to 55 percent in R-4 and 60 to 70 percent in R-6.
- In Lake Forest Park, an addition that adds 1,000 square feet of impervious surface counts as major development for tree permits.
- The first basic check is free and very quick, usually about a day. An in depth analysis is $1,500, takes 2 to 3 weeks and goes further.
Who this page is for
This page is for an owner or buyer weighing a remodel, addition or new house in Lake Forest Park or Kenmore, Washington (not Kenmore, New York). The rules differ by city, so each city has its own sections and sources below, and none of one city’s numbers applies to the other. The sources were read on 5 November 2026: ordinances, bulletins, checklists and permit pages posted by each city. Both cities keep their code on a site behind a bot check, which was not bypassed, so current code text was not read. Markup copies and older bulletins are labelled. The current code controls; confirm every number with the city. This is general information, not legal advice.
Request your free feasibility check
Send me the address of your Lake Forest Park or Kenmore house or the one you are thinking of buying, whether you are considering a remodel, an addition or a new house, the year the house was built, and the date any inspection or feasibility period ends. The first basic feasibility check is free and very quick, usually about a day. I will reply to you personally.
Prefer to talk? Call 425 753 6452 or message David on WhatsApp.
Free feasibility check
Planning a custom home or a remodel of $750,000 or more?
Send me the address and a few lines about what you want. The first feasibility check is free and usually takes about a day.
Home remodeling in Lake Forest Park: the permit path and the standards
The path. Lake Forest Park takes building applications through its online permit portal, and its permit page gives a typical review time of 8 weeks for any building permit. The city’s checklist (Help Topic 1.1) asks an addition for a scaled site plan with contours, nearby critical areas, trees of 6 inches or more, and existing and proposed lot coverage and impervious surface in percent. Height is verified by survey for all structures, and a new house needs certificates of water and sewer availability.
The standards. Ordinance 25-1310 (adopted 26 June 2025, effective 5 July 2025) amended the five single-family zones. The city’s copy is a merged markup, so only numbers that match its zoning bulletin (Help Topic 2.4, revised 11/2017) are used. In every zone the front yard is 20 feet, side yards are at least 5 feet each and 15 combined, and height is 30 feet.
| Zone | Lot coverage (buildings) | Hard surface (impervious) | Rear yard |
|---|---|---|---|
| RS-20 (20,000 sq ft lot) | 25 percent | 35 percent | 20 feet |
| RS-15 (15,000 sq ft lot) | 27.5 percent | 40 percent | 20 feet |
| RS-10 (10,000 sq ft lot) | 30 percent | 45 percent | 15 feet |
| RS-9.6 (9,600 sq ft lot) | 30 percent | 45 percent | 15 feet |
| RS-7.2 (7,200 sq ft lot) | 35 percent | 45 percent | 15 feet |
The code caps coverage as a share of “net lot area” and the bulletin says gross lot area; ask the city which it applies to your lot. See my Lake Forest Park zoning guide.
Lake Forest Park: one lot worked line by line
The lot is hypothetical: zone RS-9.6, 80 by 120 feet, which is 9,600 square feet (80 x 120), with a gentle slope that falls 7 feet from the front corners of the house to the rear corners, and no critical area or shoreline. The house is one story, 50 by 38 feet, which is 1,900 square feet of footprint with the garage, set 25 feet from the street. The driveway is 600 square feet, the walk 150 and the patio 250. The owner wants a rear addition 14 by 50 feet, which is 700 square feet, plus 200 square feet of driveway widening and 150 of new patio and walk.
| Rule | What the city says | On the hypothetical lot |
|---|---|---|
| Lot coverage, LFPMC 18.21.050 | Buildings, accessory buildings included: 30 percent of the net lot area. | 9,600 x 0.30 = 2,880. With the addition: 1,900 + 700 = 2,600, or 27.1 percent. Room left: 280 |
| Hard surface, 18.21.080 | 45 percent of the lot area; the bulletin counts footprints, paving and patios. | 9,600 x 0.45 = 4,320. Now: 1,900 + 600 + 150 + 250 = 2,900. With 700 + 200 + 150 of new work: 3,950, or 41.1 percent. Room left: 370 |
| Yards, 18.21.060 | Front 20; sides 5 each and 15 combined; rear 15. | Rear yard: 120 to 25, 38 = 57 now, 57 to 14 = 43 after. Side yards of 12 and 18 total 30 |
| Height, 18.08.160 | 30 feet above the average level of the undisturbed soil at the four corners of the smallest rectangle around the building (the city’s height bulletin, updated 2/6/2018). | Corners at 104, 104, 97 and 97 feet: 402 / 4 = 100.5, so the limit is 130.5. A ridge at 128 is 27.5 feet |
| Tree canopy goal, 16.14.070 Table 2 | 28 percent for single-family lots under 10,000 square feet. | 9,600 x 0.28 = 2,688 square feet of canopy |
Coverage is the tighter limit: 280 square feet remain against 370 of hard surface. The city’s tree sheet counts additions that add 1,000 square feet or more of impervious surface as major development, and the new work here is 700 + 200 + 150 = 1,050, so by the sheet’s wording a tree removed for it would need a major tree permit. Without the driveway widening it is 850. The city decides what counts.
Say the lot has 3,000 square feet of canopy (3,000 / 9,600 = 31.25 percent) and the plan removes trees holding 500 of it. That leaves 2,500, or 26.0 percent, below the 2,688 goal, and the sheet asks for a replacement plan that brings canopy back to the goal: 2,688 to 2,500 = 188 square feet, with an arborist assessing the canopy. My guide to existing conditions drawings covers the survey side.
Lake Forest Park: trees, slopes, the lake and an older house
Trees. The city’s tree sheets (Help Topics 2.8.A, updated 7/2026, and 2.8.B) require a removal permit for any tree over 6 inches across at breast height, and for any tree in a critical area. A viable exceptional tree at its species threshold cannot be removed even with a permit: 42 inches for Douglas fir and western red cedar, 12 for madrona. Three or more significant trees in 36 months need a major permit.
Slopes. City permit decisions, the latest published 4 December 2025, quote LFPMC 16.16.310(A): a buffer of 50 feet from the top, toe and sides of any slope of 40 percent or more, reducible to 25 feet when a qualified professional shows the smaller buffer protects the site, plus a building setback of 15 feet beyond the buffer that is not reducible: 50 + 15 = 65, or 25 + 15 = 40. The city’s older steep slope bulletin (revised 11/2017) also sets a minimum height for a slope to count, and the code chapter was not read, so ask the city whether your slope is mapped. My hillside lot guide has the slope method.
The lake. The shoreline program the city lists as current (Ordinance 1042, May 2013) reaches 200 feet landward of the water. A house gets a 50 foot setback on lots 100 feet deep or more and 40 feet on shallower ones, with 200 square feet of impervious surface allowed inside it; reductions to 25 or 20 feet need mitigation. The city’s page also shows a 2019 periodic review draft, so confirm the current text. See my Lake Washington waterfront page.
An older house. Chapter 18.66 of the city code governs nonconforming buildings, including limits on enlarging a house that does not meet today’s yards or height and a value-based point at which larger work reaches the whole building. The chapter’s current text was not read, so no threshold is given here; ask the city in writing before you design. See when a remodel counts as a new house.
Kenmore home addition: the permit path and the standards
The path. Kenmore takes building applications online through MyBuildingPermit. Its checklist (form 407, dated 8/2025) asks for a site plan with net and gross site area, impervious surface, contours at 5 foot intervals at most, and critical areas and buffers; elevations showing height and average finish grade; structural calculations stamped by a Washington engineer; and certificates of water and sewer availability from Northshore Utility District.
The standards. Table B in KMC 18.21.030 is from the city’s posted copy of Exhibit A to Ordinance 25-0630, adopted 23 June 2025 with an effective date clause of 30 June 2025. That copy prints amendments in red and says the code was current through Ordinance 24-0624, so ask the city to confirm the table in the current code.
| Zone | Street yard | Side yards | Rear yard | Height | Impervious, base and maximum |
|---|---|---|---|---|---|
| R-4 | 15 feet | 5 feet each, 15 combined | 20 feet | 35 feet | 45 percent and 55 percent |
| R-6 | 15 feet | 5 feet each, 15 combined | 20 feet | 35 feet, or 45 on slopes over 15 percent | 60 percent and 70 percent |
Table B has no lot coverage row and no floor area ratio, so none is stated. The base impervious percentage may rise to the maximum with low impact strategies the city manager approves, and for impervious surface an R-4 to R-6 lot under 9,076 square feet is held to the nearest comparable R-6 provisions. The city’s zoning map is dated as of 9 December 2024; ask Community Development to confirm your zone. See my Kenmore zoning guide.
Kenmore: height, the lake, slopes, trees and an older house
Height. The limit is 35 feet in R-4 and R-6, and 45 in R-6 for a building with a footprint on slopes over 15 percent. The city’s checklist asks for elevations showing the building height and where average finish grade strikes the building. The code section that sets the measuring method was not read, and Lake Forest Park measures from the average of four corners, so the two cities may not measure the same house the same way. Ask Kenmore how your slope will be measured.
The lake. The state-approved shoreline program (Ordinance 20-0506, posted by the Washington Department of Ecology as a March 2020 file) lists, for a house on Lake Washington in Shoreline Residential areas, a 25 foot buffer from the ordinary high water mark plus a 25 foot building setback, reducible to 5 feet if buffer vegetation is reestablished or enhanced: 25 + 25 = 50 feet from the water, or 25 + 5 = 30. In Urban Conservancy areas the buffer is 115 feet plus a 15 foot setback. The city’s shoreline map shows which applies.
Slopes. Kenmore’s critical areas code, KMC 18.55, covers landslide, erosion and other geologically hazardous areas, with buffers and building setbacks. The city’s checklist asks for a geologic hazards report from a licensed geotechnical engineer if hazardous areas are located or mapped on or next to the lot, and for the boundaries of landslide, erosion and seismic hazard areas and their buffers on the site plan. The buffer widths could not be confirmed from a city page or ordinance, so none are given; ask Development Services whether your lot is mapped.
Trees. The city’s tree page requires a removal permit unless the tree is under 6 inches across, stands on a lot with an existing single-family house, is not designated for protection and is outside any critical area or buffer. A significant tree permit is $50 and typically takes 2 weeks; an exceptional tree (48 inches or more, or a listed native below that) is $1,450 and an estimated 2 to 6 months. Fees are the city’s 2026 figures.
An older house. Kenmore’s code has rules for modifying a nonconforming structure. Their text was not read, so no rule or percentage is stated here. If your house sits inside a yard, buffer or height limit today, ask the city in writing what an addition or major remodel triggers before you design.
What to ask any architect for a project here
- Which city’s rules are we on, and is my zone confirmed in writing?
- How will height be measured on my slope? Lake Forest Park averages four corners; ask Kenmore for its method.
- How is coverage or impervious surface counted on my lot?
- Do my trees cross a permit threshold, and is my lot in a mapped slope or shoreline area?
- Who administers construction, and does your firm build?
How it works with me
First comes the free basic feasibility check, very quick, usually about a day. If you want more, an in depth analysis is $1,500, takes 2 to 3 weeks and goes further. Then I quote a fixed fee for design and permit, set by project budget and location and agreed before design starts, and design to permit submission typically takes 2 to 4 months. After the permit I administer construction. I do not build.
What it costs
The first basic check is free, the in depth analysis is $1,500, and my design and permit fee is fixed and agreed before design starts. City fees are separate. I give no per square foot construction price here; what a Kenmore home addition costs depends on the drawings, and my addition cost guide and new house cost guide cover cost.
I have been an architect since 1996, and I am a member of the AIA (since 1992) and NCARB (since 1996).
Before you hire an architect
Ask for the free first feasibility check
Send me the address and what you are considering through the request form above, or call or message me on WhatsApp. The first basic feasibility check is free and very quick, usually about a day.
Questions
How much can I add to or remodel my house in Lake Forest Park?
Two limits usually bind: lot coverage, 25 to 35 percent of the lot by zone, and hard surface, 35 to 45 percent. In RS-9.6, for example, 30 percent of a 9,600 square foot lot is 2,880 square feet for all buildings and 45 percent is 4,320 for all hard surface, and height stops at 30 feet from the average of four corner elevations. Source: Ordinance 25-1310 and the city’s Help Topic 2.4, as read on 5 November 2026; confirm with the city.
Do I need a permit to remove a tree in Lake Forest Park?
Yes for any tree over 6 inches in diameter at breast height, and for any tree in a critical area or tree conservation easement. A viable exceptional tree at or over its species threshold cannot be removed even with a permit. A major permit applies to a landmark tree of 24 inches or more, to three or more significant trees in 36 months, and to trees removed as part of work adding 1,000 square feet or more of impervious surface. Source: Help Topics 2.8.A and 2.8.B; confirm with the city.
How does Lake Forest Park measure building height?
The city’s building height bulletin (updated 2/6/2018) measures from the average level of the undisturbed soil under the building to the highest point of the structure. The average comes from the existing elevations at the four corners of the smallest rectangle that encloses the building, leaving out up to 30 inches of eaves. The city’s checklist says height is verified by survey. The limit is 30 feet in the five single-family zones.
How big a home addition can I build in Kenmore?
Kenmore’s single-family standards table has no lot coverage or floor area row, so impervious surface is the main numeric limit: 45 percent base and 55 percent maximum in R-4, 60 and 70 percent in R-6, with height at 35 feet. Yards are 15 feet at the street, 20 at the rear and 5 on each side with 15 combined. Critical area buffers, the shoreline program and trees can shrink the room. The table was read from the city’s posted copy of Exhibit A to Ordinance 25-0630, which marks amendments in red; ask the city to confirm it. What a Kenmore home addition costs depends on the drawings.
How close to Lake Washington can I build in Kenmore?
In the city’s Shoreline Residential environment, a single-family house provides a 25 foot buffer from the ordinary high water mark and a 25 foot building setback beyond it, which is 50 feet from the water. The setback can drop to 5 feet if buffer vegetation is reestablished or enhanced, which is 30 feet. In Urban Conservancy the buffer is 115 feet plus a 15 foot setback. The text is from the Washington Department of Ecology’s posted copy of the state-approved program (Ordinance 20-0506, March 2020); the shoreline map shows your environment.
Do I need a permit to remove a tree in Kenmore?
Usually yes. A permit is not needed only if the tree is under 6 inches across, the lot has an existing single-family house, the tree is not designated for protection and it is not in a critical area or buffer. The city’s 2026 fee is $50 for a significant tree and $1,450 for an exceptional tree, which is 48 inches or more or a listed native below that. A significant tree permit typically takes 2 weeks and an exceptional tree an estimated 2 to 6 months.
How long does a permit take in Lake Forest Park or Kenmore?
Lake Forest Park’s permit page gives a typical review time of 8 weeks for any building permit. Kenmore’s page says the city met the state’s permit timeline requirements in 2025 and states no typical time for a house, so none is given here.
Do I need an architect for a remodel or new house here, and do you build?
Washington’s architect licensing law does not require an architect to design a house of up to four dwelling units: RCW 18.08.410(5) exempts design work on such a residential building, including preparing construction contract documents and administering the construction contract. Whether you hire one is your choice. I design the house and administer construction for you; I do not build.
What does the free feasibility check cost, and what comes after it?
The first basic feasibility check is free and very quick, usually about a day. An in depth analysis is $1,500, takes 2 to 3 weeks and goes further. If you go ahead, I quote a fixed fee for design and permit, agreed before design starts, and design to permit submission typically takes 2 to 4 months.
