Backyard cottages, detached ADUs, garage conversions, and home additions across King and Snohomish County. Precision framing for ADU builders, GCs, and owner-builders.
Request a Free Bid Call 425-829-5660Seattle now allows up to two accessory dwelling units per residential lot — and demand for backyard cottages has never been higher. Whatever shape your ADU takes, Twin Brothers Group frames it right the first time.
Stand-alone backyard cottages from 400 to 1,000+ sq ft. We frame walls, floors, and roof systems from your stamped plan set — including Seattle's pre-approved DADU plans — with full shear wall and hardware installation per the structural drawings.
In-law suites, basement conversions, and attached secondary units. We handle structural modifications to the existing frame, new bearing walls, and floor system upgrades while keeping the main house weathertight.
Garage-to-ADU conversions including new floor framing over slabs, wall furring and insulation-ready framing, ceiling joists, and structural headers where garage doors come out and windows go in.
Room additions, second-story additions, and major structural remodels. We tie new framing into the existing structure cleanly — matching floor elevations, roof lines, and load paths per the engineer's drawings.
ADU and DADU projects move fast when the framing is planned right. Here is how we keep your backyard build on schedule.
Send us your permitted plan set — including pre-approved DADU plans — and we deliver a detailed framing bid within 48 hours, with scope, exclusions, and schedule.
ADU lots are tight. We plan material staging, crane or telehandler access, and delivery timing around your backyard site conditions before day one.
Walls, floor systems, roof framing, and sheathing — typically 2 to 4 weeks for a standard DADU. We frame to pass inspection the first time.
Punch items completed fast so MEP rough-in, windows, and siding can follow without delay. Clean handoff to your next trade, every time.
Real photos from TBG jobsites — no stock images. A West Seattle backyard DADU and a full home addition with elevated deck framing.
West Seattle DADU — wall framing and floor deck complete on a tight backyard lot.
Seattle-area home addition — new framing tied into the existing structure, with elevated deck and stairs.
TBG crew completing deck and stair framing — railings, guardrails, and structural posts per plan.
Full wraparound deck and lower-level build-out — framed, inspected, and handed off on schedule.
Twin Brothers Group is an ADU framing contractor serving general contractors, ADU builders, and owner-builders across Seattle, Bellevue, Kirkland, and the greater King County region. With Washington's middle housing laws and Seattle's two-ADUs-per-lot rules, backyard cottage construction is booming — and the framing stage is where most ADU schedules are won or lost.
We self-perform all DADU framing with our own crews — no subbing out. That matters even more on accessory dwelling units than on big projects, because ADU sites are tight, neighbors are close, and there is no room for a crew that improvises. One foreman, one point of contact, and framing that passes inspection the first time.
Looking for an experienced DADU framing contractor in Seattle? Get your free bid in 48 hours.
Seattle's DADU program — including the city's pre-approved DADU plan library — has made backyard cottages one of the fastest-growing project types in the region. Twin Brothers Group frames detached ADUs from both custom architect-designed plans and pre-approved plan sets, handling everything from sill plates and floor systems to complex roof framing and sheathing.
Our recent accessory dwelling work includes a backyard DADU in West Seattle, a combined SFR + ADU + DADU project, and full home additions across the Seattle metro. We install all Simpson hardware, holdowns, and shear wall systems per the structural drawings, and coordinate directly with your structural engineer when field conditions require it.
Whether you're a GC building a portfolio of DADUs or a homeowner managing your first ADU permit, we bring the same crews and standards we use on 200-unit multifamily projects to your backyard. Request a bid for your ADU or DADU today.
If you run an ADU construction or design-build company in Seattle, your bottleneck is rarely design or permitting — it's reliable field crews. Twin Brothers Group works as the dedicated framing subcontractor behind ADU builders, DADU specialists, and custom home builders across the metro. We frame your backlog so you can keep selling: consistent crews, fixed bids from your plan sets, and schedules you can promise clients with confidence.
Garage conversion projects get the same treatment. Converting a garage to an ADU in Seattle means structural headers where doors come out, new floor framing over existing slabs, and ceiling upgrades to meet dwelling code — work that punishes inexperienced framers. We've done it, and we bid it accurately the first time.
Building several ADUs a year? Ask about repeat-builder scheduling — we reserve crew capacity for partners with a steady pipeline. Talk to us about your next ADU project.
An ADU (accessory dwelling unit) is a secondary living unit attached to or inside the main house — like a basement apartment or attached in-law suite. A DADU (detached accessory dwelling unit), often called a backyard cottage, is a stand-alone structure on the same lot. Seattle allows up to two accessory units per residential lot, and we frame both types.
Most DADUs and backyard cottages are framed in 2 to 4 weeks depending on size, complexity, and weather. A typical 800–1,000 sq ft single-story DADU frames faster than a two-story unit with a complex roof line. We provide a framing schedule with every bid so your project timeline stays predictable.
Both. Most of our ADU and DADU framing work comes through general contractors and ADU builders, but we also frame for owner-builders who are managing their own permit and acting as their own GC. Either way, you get a detailed written bid within 48 hours.
Framing cost depends on square footage, number of stories, roof complexity, and structural requirements like shear walls and engineered beams. Rather than quoting a generic per-square-foot number, we review your actual plan set and return a detailed line-item bid within 48 hours — free, with no obligation. For background on framing costs, see our guide: How Much Does Framing Cost in Seattle?
Yes. In addition to new ADU and DADU structures, we frame garage-to-ADU conversions, home additions, second-story additions, and structural remodels throughout King and Snohomish County.
Send us your plan set or describe your project and we will respond with a detailed framing bid within 48 hours.