What a Bothell architect can design on your lot is mostly set before the first sketch. In the R-L1 and R-L2 zones the city’s table allows a house 35 feet tall, with yards of 15 feet in front, 15 in back and 5 on each side, and it caps hard surface (roofs, driveway, patio and walks together) at 55 percent of an R-L1 lot and 60 percent of an R-L2 lot. On the worked lot below, 9,100 square feet in R-L1, that cap is 5,005 square feet, and, reading the city’s 60 percent floor area line for a water and sewer certificate against the existing house, a 1,200 square foot addition crosses it while a 1,100 square foot one does not. My first basic feasibility check is free and very quick, usually about a day: send me the address and what you are thinking of building. An in depth analysis is $1,500, takes 2 to 3 weeks and goes further. I design and administer construction; I do not build.
Key takeaways
- On a 9,100 square foot R-L1 lot the hard surface cap is 9,100 x 0.55 = 5,005 square feet.
- The city checklist asks for a water and sewer certificate when floor area grows by more than 60 percent (it does not say of what). Against a 1,900 square foot house that is 1,140 square feet: a 1,100 square foot addition is 57.9 percent, a 1,200 square foot one 63.2.
- Bothell sits in both King and Snohomish counties. The city’s table has no King or Snohomish column; septic approval comes from King County Health or the Snohomish Health District.
- The city’s listed first review is 4 weeks for an addition or a new house and 3 for an interior remodel, then 2 to 3 weeks per later review.
Who this page is for
This page is for an owner or buyer of a house or lot in the City of Bothell, Washington who is choosing an architect for a remodel, an addition or a new house. The sources were read on 5 November 2026. The city’s online code site sits behind a bot check and was not bypassed. The code figures come from a city PDF titled Proposed Code Redlines, listed with the notice of a 16 September 2026 Planning Commission hearing on land use procedures. Its BMC 12.14.030 pages say they are current through Ordinance 2483 (12 May 2026) and show no markup on the rows used here; the file marks one proposed change elsewhere in that section, on multifamily phasing. A redline file is a draft working document, so the code in force controls. Confirm every number with Planning at planning@bothellwa.gov. This is general information, not legal advice. Washington’s architect licensing chapter does not reach design work on a residential building of up to and including four dwelling units (RCW 18.08.410(5)), so hiring an architect is your choice.
Request your free feasibility check
Send me the address of your Bothell house or the one you are thinking of buying, whether you are considering a remodel, an addition or a new house, and what you want from it. 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.
Two counties, one city
The city’s Imagine Bothell plan update (December 2024) says Bothell straddles the boundary between King and Snohomish County. The Printable Maps page lists a City County Map (October 2026) showing both divisions inside the city limits. Check your parcel there first.
| Question | Who decides | Source |
|---|---|---|
| Yards, height, hard surface | The City of Bothell, one table | BMC 12.14.030 |
| Building permit, plan review | The City Permit Center, online at MyBuildingPermit.com | Permit Center page |
| Septic approval | King County Health or Snohomish Health District, if the lot is on septic | Forms 3 and 3b |
| Water and sewer | The city, or Alderwood, Northshore or Woodinville | Forms 3 and 3b |
The Permit Center page names no separate office for either county, and the table has no King or Snohomish column. My Bothell zoning and permit guide covers the table and the fee forms.
What a Bothell home architect checks first
The residential table has one column per zone. These are its first three, with the rows that size a house:
| Limit | R-C | R-L1 | R-L2 |
|---|---|---|---|
| Front yard, garage door | 20 feet | 20 feet | 20 feet |
| Front yard, all others | 15 feet | 15 feet | 15 feet |
| Rear yard, no alley | 35 feet | 15 feet | 15 feet |
| Side yard | 5 feet | 5 feet | 5 feet |
| Maximum building height | 35 feet | 35 feet | 35 feet |
| Maximum hard surface coverage | 35 percent | 55 percent | 60 percent |
The notes add rules. No hard surface may sit in the front yard except driveways, walkways and structures allowed to project into the setback; a front yard driveway is no wider than three vehicles need. The city’s checklists measure roof area by vertical projection from its widest points, so overhangs appear to count, and add driveways, walkways, patios, porches and decks; a front yard walkway is no wider than 5 feet. Where a critical area is on the lot, BMC Title 14 further regulates impervious coverage, and hard surface legally built before 31 December 2016 that exceeds today’s limit falls under the nonconforming chapter, BMC 12.26; neither was read, so ask Planning.
Height is measured from average city-approved finished grade: the city’s Form H says to draw the smallest rectangle around the building and average the existing ground elevations at the midpoint of each side. Within 2 feet of the limit, or on a sloped lot, a licensed surveyor verifies height at the roof sheathing inspection. Midpoints of 100.0, 102.0, 106.0 and 104.0 feet average (100 + 102 + 106 + 104) / 4 = 103.0, so a 35 foot limit reaches 138.0, and a design at 136.0 or higher is within 2 feet. The roof point that counts is set in BMC 12.14.110, which was not read. The new house checklist (July 2025) still asks for a narrative to justify a height over 30 feet, citing footnote 6, which in the table copy is the hard surface note; ask Planning which reading applies.
Worked lot: an addition on 9,100 square feet
The worked lot is hypothetical, not a real property or a client’s: 70 feet wide and 130 deep, 9,100 square feet, flat, zone R-L1, no critical area or shoreline. The existing house is one story with an attached garage, 1,900 square feet of floor area and of roof footprint (overhangs ignored). The driveway is 18 by 35 feet (630), the walk 150 and the patio 400, so paving is 1,180 and hard surface is 3,080 (1,900 + 1,180), 33.8 percent of the lot.
| Step | Arithmetic | Result |
|---|---|---|
| Building envelope | (70 minus 5 minus 5) x (130 minus 15 minus 15) = 60 x 100 | 6,000 sq ft |
| Hard surface cap | 9,100 x 0.55 | 5,005 sq ft |
| Hard surface room | 5,005 minus 3,080 | 1,925 sq ft |
| 60 percent line, read against existing floor area | 1,900 x 0.60 | 1,140 sq ft of added floor area |
| Option | Hard surface after | Floor area added | What the checklist then asks for |
|---|---|---|---|
| A. One story addition, 1,100 sq ft | 3,080 + 1,100 = 4,180 (45.9 percent), 825 under the cap | 1,100 / 1,900 = 57.9 percent, not over 60 | No water and sewer certificate on that line; a fire flow letter, and footing and roof drains because the footprint changes |
| B. One story addition, 1,200 sq ft | 3,080 + 1,200 = 4,280 (47.0 percent), 725 under the cap | 1,200 / 1,900 = 63.2 percent, over 60 | A water and sewer certificate before you apply; the city says allow 2 weeks if it is your provider |
| C. Second floor, 1,900 sq ft | 3,080, unchanged (33.8 percent) | 1,900 / 1,900 = 100 percent | A water and sewer certificate, and structural calculations, which the checklist asks for on story additions |
On this lot the 60 percent line, not the hard surface cap, is the first rule you meet, and a second floor leaves hard surface alone. The checklist does not say whether a garage counts in the floor area it compares, or what the 60 percent is measured against; this page reads it against the existing house. The May 2026 table has no building coverage row, yet the city’s July 2025 addition checklist still asks for a building coverage calculation under BMC 12.14.140(A); ask whether a cap applies.
What an addition or remodel sets off
The additions and alterations checklist (Form 3b) lists the minimum items the city needs to accept an application. Besides the 60 percent item it asks for:
- A fire flow letter from the water provider for an addition; if the flow is not available, sprinklers may be required.
- Structural calculations for story additions, and a soils report under BMC 14.04.210 where a sensitive area is on the area to be altered.
- A site plan for everything except an interior only remodel, with contours (2 foot intervals under 15 percent slope, 5 foot at 15 percent or more) and sensitive areas within 200 feet.
- Footing and roof drains for any change to the building footprint, the footing drain to the city’s detail 497.
My existing conditions guide explains why the existing house matters to this list, and the structural engineer guide covers story additions.
If the house is new
A teardown starts from today’s table, not the old house’s yards. The new single family checklist (Form 3) adds an assigned address and a water and sewer certificate before you apply (up to two weeks when the city is the provider); a fire flow letter showing 1,500 gpm at 20 psi for 2 hours, with more possible for residential structures over 3,600 square feet, attached garage included; a geotechnical report unless adjacent data shows none is needed; and a drainage report if impervious area grows by more than 5,000 square feet.
On the worked lot, a two story house on a 2,300 square foot footprint with the same 630 driveway, 150 walk and 400 patio has 3,480 square feet of hard surface (2,300 + 630 + 150 + 400), 38.2 percent, under the 5,005 cap. The drainage report line is about an increase: 3,480 minus today’s 3,080 is 400, far under 5,000, though the checklist says impervious surface and the table says hard surface. Two full floors make 4,600 square feet, over the 3,600 line if the garage is attached. The city’s review table lists demolition over the counter, or 2 to 4 weeks if the building is more than 50 years old, historic or significant. See my demolition permit guide and guide to when a remodel counts as a new house.
Slopes, streams and trees
The Imagine Bothell plan update describes the city’s topography as primarily a series of hills with steep slopes sensitive to development. The critical areas form (Form 25) asks whether a lot has slopes greater than about 15 percent, and whether mapped or known wetlands, flood, geologic hazard or habitat areas lie on or within 300 feet. Buffer widths and the slope that triggers review sit in BMC Title 14, which was not read, so none are quoted. See my sloped lot guide.
Three waterways carry shoreline rules. The city’s Shoreline Master Program (state-approved copy hosted by Ecology, adopted 6 February 2013, code print current through Ordinance 2371 of 14 December 2021, later changes not checked) covers the Sammamish River, North Creek and Swamp Creek and land within 200 feet of the ordinary high water mark. Its table lists a 35 foot height and a 5 foot side yard in the Shoreline Residential environment, and buffers of 100 feet on the Sammamish River and North Creek and 150 on Swamp Creek there; the North Creek main stem between 240th and 228th Streets SE has 150 in every environment. BMC 13.13.010(I) in that copy sets buildings back 15 feet from a buffer edge. If the high water mark sat on the rear line of a hypothetical 220 foot deep lot on Swamp Creek, 220 minus 150 leaves 70 feet, the 15 foot setback leaves 55 and a 15 foot front yard leaves 40 for the house, before any buffer reduction or later change. My shoreline exemption guide covers the state permit.
For trees, the Permit Center page says a permit is generally not required only if the lot is an existing lot of record under 20,000 square feet, more than 5 years have passed since the subdivision and no critical area is present (wetlands, streams, slopes steeper than 40 percent, or a shoreline designation). Trees in critical areas need approval to remove. The city is aiming to adopt an updated tree code by early 2027.
The permit path and review times
The Permit Center page says new construction uses the 2021 edition of the building codes. A remodel with no added square footage is priced by valuation, including tax; additions and new houses by square footage and construction type, from a fee quote. I give no fee figures here. The permit processing time sheet (Form B, updated September 2025) lists:
| Permit | First review | Later reviews | Arithmetic on the city’s times |
|---|---|---|---|
| Single family remodel, interior only | 3 weeks | 2 to 3 weeks each | 3 + 2 x (2 to 3) = 7 to 9 weeks |
| Single family addition | 4 weeks | 2 to 3 weeks each | 4 + 2 x (2 to 3) = 8 to 10 weeks |
| Single family new construction | 4 weeks | 2 to 3 weeks each | 4 + 2 x (2 to 3) = 8 to 10 weeks |
| Critical area alteration | 8 weeks | 3 to 5 weeks each | Listed separately |
Two later reviews is my assumption. The sheet says to add one to two weeks, or more, during high permitting volumes: for an addition, 9 to 12 weeks. For cost, see my home addition cost guide; the number depends on the drawings.
What to send me
The address or parcel number is enough to start. It helps to add:
- A remodel, an addition or a new house, and the changes you want.
- Any survey, existing drawings or permit history you already have.
- Whether the lot has a slope, a stream or wetland nearby.
- Whether you are buying, and when your inspection period ends.
How it works with me
The first basic feasibility check is free and 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 than the first check. If you go ahead, my fee for design and permit is fixed and agreed before design starts. Design to permit submission typically takes 2 to 4 months. After the permit I administer construction for you; I do not build.
I have been an architect since 1996, and I am a member of the AIA (since 1992) and NCARB (since 1996).
Before you draw
Ask for the free first check
Send me the address 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 do I choose a Bothell architect for a remodel, an addition or a new house?
Ask for your lot’s numbers before design: yards, hard surface limit, height, slope and stream checks, trees and which county the parcel sits in. Ask how the fee is set and who administers construction. My fee is fixed and agreed before design starts, and I administer construction; I do not build. Washington’s architect licensing chapter exempts design work on a residential building of up to and including four dwelling units (RCW 18.08.410(5)), so the choice is yours.
What can I build on my Bothell lot?
In R-L1 and R-L2 the city’s table allows a house 35 feet tall with yards of 15 feet front, 15 rear and 5 each side (20 feet to a garage door), and hard surface of 55 percent in R-L1 and 60 percent in R-L2. On a 9,100 square foot R-L1 lot that is 5,005 square feet of roofs, driveway, patio and walks. Slopes, streams, shoreline and trees add review. The figures come from a city PDF titled Proposed Code Redlines that prints BMC 12.14.030 as current through Ordinance 2483; the code in force controls, so confirm with Planning.
Is my Bothell property in King County or Snohomish County, and do the rules change?
Bothell straddles the line, and the city publishes a City County Map showing the divisions inside its limits. The city’s table has no King or Snohomish column. Septic approval comes from King County Health or the Snohomish Health District, and water and sewer from the city, Alderwood, Northshore or Woodinville. Check the map and the Permit Center for your parcel.
How much of my Bothell lot can I cover?
Hard surface is capped at 35 percent in R-C, 55 in R-L1 and 60 in R-L2. The city’s checklists count roofs (by vertical projection), driveways, walkways, patios, porches and decks. On a 9,100 square foot R-L1 lot with 3,080 square feet already, an addition of 1,100 square feet reaches 4,180, under the 5,005 cap. The city’s checklist also asks for a building coverage figure, so ask Planning whether a cap applies.
What does a home addition set off in Bothell?
The city’s checklist asks for a fire flow letter from the water provider, structural calculations for a story addition, footing and roof drains if the footprint changes and a soils report if a sensitive area is on the area to be altered. If floor area grows by more than 60 percent, a water and sewer certificate is needed first; on a 1,900 square foot house the line is 1,140 square feet, and the city says to allow 2 weeks when it is your provider.
How long does a Bothell building permit take?
The city’s September 2025 sheet lists a first review of 3 weeks for an interior single family remodel and 4 weeks for an addition or new house, then 2 to 3 weeks per later review. It says to add 1 to 2 weeks or more when volume is high. Critical area alterations list 8 weeks. Actual times vary.
Do I need a permit to remove a tree in Bothell?
Often yes. The city says a permit is generally not required only if the lot is an existing lot of record under 20,000 square feet, more than 5 years have passed since the subdivision and there is no critical area: wetlands, streams, slopes steeper than 40 percent or a shoreline designation. The city is aiming to adopt a new tree code by early 2027.
What does a home addition cost in Bothell?
It depends on the drawings, so I give no figure on this page; see my home addition cost guide. The city prices a remodel with no added square footage by valuation, including tax, and an addition by square footage and construction type through a fee quote it returns within a week.
What does the feasibility check cost, and do you build?
The first basic feasibility check is free and very quick, usually about a day. An in depth analysis is $1,500 over 2 to 3 weeks. If you go ahead, I quote a fixed fee for design and permit, agreed before design starts. Piper Cole Architects designs and administers construction. We do not build.
