Modern modular ADU with glass frontage and silver exterior finish

California modular ADU cost intelligence

Modular ADU Cost System.

ADU Cost is the product-first quoting hub for a fold-out modular ADU package with California Factory Built Housing approval documentation, interior finish catalogs, and a calculator built for the true all-in scope: unit, freight, foundation, utilities, permits, setting, and finish allowances.

Open cost calculator View product package

CA FBH approvals referenced 1L + 3L plan packets No fake price promises

Codex product upgrade

The site now sells the decision system, not just the module.

A serious ADU buyer needs to see the product, the approvals, the unknowns, and the cost stack at the same time. This upgrade turns the homepage into a product command center: model choice, proof documents, site-scope boundaries, and a calculator path that never hides missing numbers.

Budget readiness Product-first

Model packet1L + 3L

Approval filesR-22345 / R-22348

Scope ruleFactory vs site separated

Pricing ruleNo invented numbers

Open 3L approval PDF

Model lab

Two real product paths: compact 1L or larger 3L.

R-22348

1L one-bedroom ADU

Best positioned as the lean backyard rental, guest unit, parent suite, or fast feasibility option when the buyer wants a smaller footprint and a cleaner budget conversation.

One-bedroom plan packet
Kitchen orientation noted as left side
CA FBH approval dated 2026-07-15

Review 1L model

R-22345

3L three-bedroom ADU

The larger product story: a 962.40 sf gross area package with a 931.63 sf net indoor area shown in the plan packet, built for buyers comparing a real dwelling, not a shed.

37.23 x 25.85 x 10.50 ft unfolded size
9.84 ft interior ceiling height
One set noted for a 40 ft open-top container

Review 3L model

Product motion

The fold-out sequence makes the product easy to understand in seconds.

The homepage now uses the real product demo video, plus frame-derived education stills, so a buyer can see that this is a modular dwelling system with assembly stages and not a generic ADU stock photo.

Scope ledger

Every serious quote needs six cost buckets before it can be trusted.

01Factory packageModule, plan packet, product selection. 02Freight + settingContainer, route, crane, staging. 03FoundationPad, anchors, drainage, engineering. 04UtilitiesWater, sewer, electric, gas, trenching. 05PermitsCity review, plan check, impact fees. 06FinishesFlooring, wall panels, upgrades, contingency.

Search-demand gap map

The next content layer follows what ADU buyers are already searching.

The keyword-gap research showed strong intent around prefab ADU cost, ADU building permits, ADU cost calculators, modular ADUs, and the real cost to build an ADU. The site now answers those searches with focused pages instead of repeating the same generic ADU pitch.

Prefab ADU costFactory package vs installed budget ADU building permitsPermit and plan-check cost buckets ADU cost calculatorKnown numbers vs missing allowances ADU site work costFoundation, utilities, setting, access

ADU education center

Teach the buyer what an ADU is, then teach this product specifically.

The stronger site is not only a calculator. It explains accessory dwelling units, the California factory-built housing lane, what the fold-out product package includes, what the R-22345 and R-22348 documents prove, and which local costs still need a real site review.

01What is an ADU?Plain-English accessory dwelling unit basics. 02How this product worksFold-out module, transport logic, and buyer path. 03Factory approval vs local permitThe important boundary before money moves. 041L and 3L specsSource-backed facts from the approval packets. 05Site work and installationFoundation, utilities, access, setting, inspection. 06FinishesFlooring and wall-panel catalog education.

Structural engineering layer

Show the drawings before asking a buyer to trust the budget.

The R-22345 and R-22348 packets are now used as visible education assets. A buyer can see the approval criteria, model drawings, steel-frame logic, SIP assembly notes, wind-pressure path, and engineering-analysis outputs before opening the calculator.

This section keeps the honest boundary in view: the factory-built structure documentation supports product review, while foundation, anchorage, utilities, placement, and local inspection remain site-specific work for the project team and authority having jurisdiction.

3L structural page 1L structural page

R-22345 steel connection details from approval packet — 3L steel member and connection sheet

R-22348 ETABS steel analytical model from engineering packet — 1L ETABS steel analytical model

The product

Modern fold-out dwelling shell, finish systems, and plan documentation in one quoting flow.

The source packet includes a 3L three-bedroom plan package, a 1L one-bedroom plan package, Kingdom flooring, Kingdom wall panels, exterior product photos, and an unfold video. The site is designed to make those pieces understandable for a homeowner, investor, or contractor before a formal quote.

962.40 sf3L gross area shown in the plan package

931.63 sf3L net indoor area shown in the plan package

2029R-22345 and R-22348 approval expiration year

Top view of compact modular ADU interior layout — Video-derived unfold frame used as product education, not a permit drawing.

Cost stack

ADU cost is not one number. It is a stack.

Factory unit package Freight, crane, and setting Foundation and pad Water, sewer, electric, gas Permits and local fees Finish allowances

Truth gate

Factory approval is not the same as full site approval.

The engineering letters state that the approval covers the factory-built structure only, and that foundation, site work, utility connections, roofing/sealing items, and local authority review remain part of the project. ADU Cost keeps that boundary visible so the sales conversation stays credible.

Read approval boundary

R-22345 3L three-bedroom ADU package Approval date 2026-07-15 / Expiration 2029-07-14

R-22348 1L one-bedroom ADU package Approval date 2026-07-15 / Expiration 2029-07-14

Copper exterior finish modular ADU product photo — Copper finish option

Wall panel frame detail from unfold video — Wall panel assembly

Floor connection detail from unfold video — Floor connection detail

Next move

Build the first budget with real allowances, then tighten it with a supplier quote.

Start with the calculator, then send the scope packet with your preferred model, target city, site access notes, and utility assumptions.

Start calculator