Build More Homes on the Lot You Already Own

ZH Construction designs, permits and builds duplexes, triplexes, fourplexes, townhomes and cottage clusters on residential lots in Snohomish County and North King County — from the first zoning check to the final inspection.

Check What My Lot Allows Estimate Build Cost & Return

1Single-family lot

1 HOME

STREET

2Tier 2 & Tier 3 baseline

UNIT A

UNIT B

DRIVE

STREET

4Tier 1 baseline · Tier 2 near major transit

TH 1

TH 2

TH 3

TH 4

SHARED DRIVE

STREET

6Tier 1 near major transit

1

2

3

4

5

6

STREET

Lynnwood-basedMiddle housing onlyWA registered contractorOne team from feasibility to keys

A new row of townhomes below a hillside neighborhood, with a lake and mountains behind

New townhomes

Townhomes

Several wood-framed homes under construction on one street

New construction

01

Single-Family Lots Are No Longer Single-Family Only

Washington's middle housing law (HB 1110, later amended by ESHB 2321) requires most cities in the Puget Sound region to allow two, four or even six homes on lots that used to permit just one house. The law sets a statewide minimum; many cities have written codes that go further.

That change turns an ordinary 7,200-square-foot lot with a tired 1960s rambler into a site for a duplex, a row of townhomes or a small cottage court. Most owners have never built anything like this. That is the gap ZH Construction fills.

Definition

Middle housing is the range of home types between a detached house and an apartment complex: duplexes, triplexes, fourplexes, fiveplexes, sixplexes, townhouses, stacked flats, courtyard apartments and cottage housing.

02

What the State Law Requires — At Minimum

City size (state "tier")	Units per lot, baseline	Within ¼ mile walk of a major transit stop	With affordable units
75,000+ residents (Tier 1) — e.g. Everett	at least 4	at least 6	at least 6 if 2 are affordable
25,000–75,000 (Tier 2) — e.g. Lynnwood, Edmonds, Shoreline, Bothell, Marysville, Lake Stevens	at least 2	at least 4	at least 4 if 1 is affordable
Under 25,000 inside the contiguous urban growth area (Tier 3) — e.g. Mountlake Terrace, Mill Creek, Mukilteo, Kenmore, Lake Forest Park	at least 2	no added transit minimum	no added minimum

These are floors, not ceilings. A city's own code can allow more, and some do. Our lot review reads the current code for your parcel, not just the state baseline.

Read the full plain-English breakdown

03

What We Build

UNIT A

UNIT B

DRIVE

STREET

Duplexes

two homes side by side or stacked; the simplest way to add a unit and the easiest to finance.

Duplexes

1

2

3

4

BIKES

STREET

Triplexes & Fourplexes

three to six homes in one building where the city allows it.

Triplexes & Fourplexes

TH 1

TH 2

TH 3

TH 4

SHARED DRIVE

STREET

Townhomes

attached homes on their own unit lots, each sellable separately.

Townhomes

GREEN

C1

C2

C3

C4

C5

SHARED PARKING

STREET

Cottage Housing

small detached homes around a shared green.

Cottage Housing

OLD HOUSE

STREET

TH 1

TH 2

TH 3

TH 4

SHARED DRIVE

STREET

Teardown & Rebuild

remove the old house and replace it with multiple new homes.

Teardown & Rebuild

ONE HOME

NEIGHBOR

NEIGHBOR

STREET

Custom Infill Homes

one new home on a narrow, split or leftover lot.

Custom Infill Homes

LOT 1

LOT 2

LOT 3

LOT 4

EASEMENT

STREET

Unit Lot Subdivision

divide the parcel so each new home gets its own lot and title.

Unit Lot Subdivision

UNIT A

UNIT B

DRIVE

STREET

Option A

TH 1

TH 2

TH 3

TH 4

SHARED DRIVE

STREET

Option B

GREEN

C1

C2

C3

C4

C5

SHARED PARKING

STREET

Option C

Feasibility, Design & Permits

the pre-construction work, sold on its own if you want it.

Feasibility, Design & Permits

04

Two Tools to Start With

Tool 01What Can I Build?Enter your city, lot size and distance to transit. The tool shows the state-minimum unit count, the parking cap and the housing types that typically fit — plus the site issues that most often stop projects.What Can I Build?Tool 02Build Cost & Return CalculatorEnter unit count, size and finish level. See an estimated all-in project cost, the projected value of the units if sold, and the rental income if held.Build Cost & Return Calculator

05

Who We Work With

Homeowners who want to stay

Build a duplex, live in one side and rent the other — or replace your house with townhomes and keep one for yourself.

Owners of an inherited or aging house

Instead of selling an old rambler as-is, redevelop the lot and capture the value of two to six new homes.

Small investors and first-time builders

You have the land or the capital but not the construction team. We act as the general contractor and run the whole process.

Families planning multigenerational living

Separate front doors, separate kitchens, one property.

06

How a Project Runs

01Lot review (free)Zoning, unit count, utilities, slopes, trees and access — in writing.

02Feasibility packageSite plan options, cost range and a simple pro forma.

03Design and engineeringArchitect, civil and structural coordinated by us.

04PermitsPre-application meeting, submittals, corrections, approvals.

05ConstructionDemolition, site work, utilities, building, inspections.

06CloseoutFinal inspections, unit lot recording, warranty walk-through.

Full detail → Process

07

Why Owners Choose ZH Construction

01

We only build middle housing

Not kitchens, not roofs, not decks. Every project on our schedule is a multi-unit infill build, and the team knows its specific traps: fire separations, separate utility meters, shared-wall details, unit lot plats.

02

We start with the numbers

Every project starts with a pro forma, not a sales pitch. If the lot does not pencil out, we say so.

03

One contract, one point of contact

Design, permits and construction under one agreement, with a single project manager from day one.

04

Local permit experience

Snohomish County cities each handle middle housing differently. We plan around the review process of the specific city, not a generic timeline.

08

Where We Build

LynnwoodT2 EverettT1 EdmondsT2 Mountlake TerraceT3 ShorelineT2 BothellT2 Mill CreekT3 MukilteoT3 MarysvilleT2 Lake StevensT2 KenmoreT3 Lake Forest ParkT3

All service areas

09

Frequently Asked Questions

QCan I really build a duplex on my single-family lot?

In most Puget Sound cities with 25,000 or more residents, yes — state law requires them to allow at least two units per residential lot. Smaller cities inside the urban growth area must also allow at least two. Site conditions such as sewer access, steep slopes or wetlands can still limit a specific parcel.

QDo I have to sell the units?

No. You can keep and rent all of them, live in one, or sell some through a unit lot subdivision. The best route depends on your financing and tax situation.

QHow long does a middle housing project take?

A duplex usually runs 14–20 months from first meeting to move-in; a four- to six-unit townhome project, 18–28 months. Permitting is typically the longest single phase.

QDo you build ADUs?

No. We focus on attached and multi-unit housing.

QWhat does a lot review cost?

Nothing. You get a written summary within two business days.

Free lot review

Find Out What Your Lot Can Become

Send us the address. Within two business days you get a written lot review: how many units the city allows, what the site will cost to prepare, and which housing type makes the most sense for your goals.

Get a Lot Review Call (425) 555-0164