Finished attached ADU in Bellevue, WA built by MNBE Construction & Development

Project · Bellevue, WA · 2024

Bellevue Attached ADU. The Heywood residence.

A finished attached accessory dwelling unit on a Bellevue residential lot. Navy lap siding, dual entry doors, full kitchen, full bath, code-compliant ventilation. Built end-to-end by MNBE in 2024. 5-star verified Google review at handover.

Type

Attached ADU (AADU)

Location

Bellevue, WA

Year Completed

2024

Scope

Design + permit + build

The Story

An attached ADU that solved the lot.

The Heywoods came to us with a Bellevue lot. Bellevue's current code only allows attached ADUs (no detached DADUs), so an attached unit was the answer from day one. The challenge was making it feel intentional rather than tacked-on.

Sharing one wall with the existing house cut the foundation scope significantly. Sharing the utility runs eliminated 60 feet of trenching across the existing landscape. The existing house got a small addition for the connection point. The result reads as one cohesive home with a clear second front door.

The scope of work covered everything: concrete foundations, full framing, roofing, kitchen installation, exterior siding, windows and doors, HVAC and mini-splits, complete bathroom, and all construction materials. Aaron also handled all communication with the City of Bellevue, coordinated every required inspection, and made sure the project passed each one without any issues.

The project finished on schedule. Zena Heywood left a 5-star verified Google review describing the experience as "smooth, professional, and stress free."

Scope of Work

What we built.

Concrete foundations and footings tied into existing structure

Complete wood framing, advanced framing techniques

Full roofing tied into existing roofline

Exterior siding (navy lap) and trim

Windows and exterior doors with code-compliant egress

HVAC and mini-split installation

Complete kitchen with cabinets, counters, appliances

Code-compliant bathroom with tile shower

Dedicated electrical subpanel and wiring

Plumbing rough-in and finish

Drywall, paint, flooring, lighting, hardware

City of Bellevue permits + inspections through CO

The Reveal

The Finished Build.

Before we walk you through the build, here is what it looks like finished. The orange-door entry from outside, the open-plan living, the kitchen and island, and a full bath.

Finished AADU exterior with orange front door, navy lap siding, and lavender beds — The orange-door entry

The Build · Chronological

Thirteen stages, four months start to finish.

From excavation to a finished AADU in four months. Every photo from the actual job site, taken by Aaron and his crew during the work.

Stage 01
Excavation & site prep
Lot cleared and excavated for the AADU footprint. Wood form boards laid out around the perimeter. Garden shed visible at back, existing house behind the camera. Day one.
Stage 02
Foundation forms + rebar
Wood foundation forms set with rebar tied inside the perimeter walls. Plywood spans for the footings. Excavator-cleared dirt mounded outside the footprint, ready for backfill after the pour.
Stage 03
Foundation walls poured + gravel pad
Perimeter foundation walls poured (smooth grey concrete visible at edges). Gravel base placed inside the footprint, leveled, and compacted. Ready for vapor barrier and slab pour.
Stage 04
Slab rebar grid + conduit
Full rebar grid tied across the slab footprint. Electrical conduit and plumbing rough-in pre-laid through the rebar. Vapor barrier underneath. Inspector-ready.
Stage 05
Framing crew on site
First wall studs going up. Two crew members on site, measuring, cutting, plating. Cut-list and plans on the slab. The slab is now the floor and the AADU starts to take shape.
Stage 06
Walls framed + tied to existing house
Full wall framing in place, attached at one shared wall to the existing house. The AADU footprint is now defined in three dimensions. Subfloor visible inside the framing.
Stage 07
Interior partitions + door headers
Looking through the AADU framing toward the existing house. Door headers cut, interior partition walls being built. Concrete slab visible underneath, pre-finish flooring.
Stage 08
OSB sheathing + roof structure
Walls sheathed with OSB. Roof framing complete with OSB roof sheathing visible up top. Window and door rough openings cut into the sheathing. Building is now structurally complete.
Stage 09
Tyvek house wrap (dry-in)
Tyvek HomeWrap applied across the full envelope. Door and window openings cut and taped. The structure is now weatherproofed against Pacific NW rain while interior work continues.
Stage 10
Windows installed + siding starting
Three new windows installed, front door hung, and exterior siding starting at the top. Worker carrying a saw mid-cut. The project moves visibly from "under construction" to "almost a building."
Stage 11
Interior MEP rough-in
Interior framing fully complete with skylight rough-in visible at the ceiling. Plumbing PEX (blue), electrical conduit, and HVAC ducting all run inside the wall cavities. Pre-drywall inspections happen at this stage.
Stage 12
Drywall hung + ceilings finished
Drywall hung across walls and ceiling. Green moisture-resistant board in the bathroom area (left). Skylights flood the space with natural light. Recessed lights installed in the ceiling. Mud and tape next.
Stage 13
Finished interior + handover
The finished interior at handover. Full galley kitchen with white shaker cabinets and quartz counters on the left, island with seating, dining and living space at the back. Two skylights flood the AADU with natural light. Hardwood floors throughout. Move-in ready.

From Google

What the Heywoods said.

Zena Heywood

3 reviews

5 months ago

We hired Aaron from MNBE Construction & Development to build our ADU in Bellevue, and the entire experience was amazing. Aaron handled absolutely everything for us from the very beginning until completion. The scope of work included concrete foundations, full framing, roofing, kitchen installation, siding, windows and doors, HVAC and mini-splits, a complete bathroom. The process was smooth, professional, and stress free. The quality of workmanship is outstanding, and the ADU turned out better than we imagined.

Posted on Google

Helpful

Bellevue, WA · December 2025

Service

AADU Service Page

The full attached ADU service breakdown.

See AADU service →

Project

Redmond DADU

100-year-old structure rebuilt to studs. Verified Google review.

See Redmond →

The Law

HB 1337 Explained

The 2023 law that made attached ADUs like this one possible across WA.

Read the guide →

5.0 on Google · HomeAdvisor

Start Your Build

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Contact information

Thank you for considering MNBE for your project. We'll get back to you during normal business hours, Monday through Saturday.

+1 (206) 637-0044 MNBE.service@gmail.com

2014 Fairview Ave Unit 2308
Seattle, WA 98121

Bellevue Attached ADU. The Heywood residence.

An attached ADU that solved the lot.

What we built.

The Finished Build.

The orange-door entry

Open-plan living

Kitchen + island

Full bathroom

Thirteen stages, four months start to finish.

Excavation & site prep

Foundation forms + rebar

Foundation walls poured + gravel pad

Slab rebar grid + conduit

Framing crew on site

Walls framed + tied to existing house

Interior partitions + door headers

OSB sheathing + roof structure

Tyvek house wrap (dry-in)

Windows installed + siding starting

Interior MEP rough-in

Drywall hung + ceilings finished

Finished interior + handover

What the Heywoods said.

More from MNBE.

AADU Service Page

Redmond DADU

HB 1337 Explained

Tell us about your project.