Home Addition Drawings · Brentwood, CA
Permit-Ready Home Addition
Drawings for Brentwood, CA
Expand your home with a permitted room addition, second story, or family room extension. We deliver complete, code-compliant drawing sets for Brentwood's building department — 14-day money-back guarantee.
14-day money-back guarantee · permit-ready delivery
Local Intelligence
What Brentwood Homeowners Need to Know Before Submitting
Size & Zoning Rules
Any new square footage added to your Brentwood home counts against the same zoning envelope that governs ADU size, meaning large additions may affect your ability to add a future ADU. Brentwood's current ADU size cap is 1,000 sq ft — within the typical range for most floor plan configurations.
Brentwood does not impose an owner-occupancy requirement, so you can rent both the main home and any ADU or conversion as investment units.
If the addition creates a second unit or is later converted to a rental, Brentwood's ADU market supports approximately $2,768/month for a 2-bedroom unit.
Permit Process & Fees
Community Development Department permit fees for this project type typically range from $4,000 to $15,000 depending on project valuation and scope. Plan check runs approximately 12 weeks — though each correction cycle adds 3–6 weeks, which is why code-compliant drawings matter so much.
Addition permit packages submitted to Community Development Department must include a site plan, floor plans, all four elevations, an electrical plan, and energy compliance documentation — plus stamped structural drawings are always required for any load-bearing elements, second-story work, or new foundation.
Visit Community Development Department ↗Construction Cost Context
Brentwood's home addition construction costs run $180–$440 per square foot — a wide range driven by labor markets, local code complexity, and finish level. Our drawings are priced at a fraction of what a full-service architect would charge to produce the same permit set.
⚠ Common Pitfall in Brentwood
If your property is within a Brentwood HOA, expect additional friction during the design phase, as many HOAs enforce architectural consistency rules that go beyond city requirements, potentially delaying approval by weeks or months. Additionally, ADUs over 750 sqft trigger school district impact fees that can add $3.50–$4.14 per square foot, which often surprises homeowners budgeting for smaller units. On older properties, utility upgrades—especially sewer line replacements—are common due to Brentwood's aging infrastructure, often adding $10,000–$15,000 to the project cost.
Expert Verdict — Marcus Reid, Licensed Designer
"In my experience filing ADU plans in Brentwood, that 12-week timeline and the per-square-foot cost figure are both state-level averages, not verified local numbers — I'd get quotes from at least two Brentwood-experienced contractors and call the Community Development Department directly before penciling out a budget or schedule. And don't overlook that HOA hitting 50% of properties here; even with no coastal overlay to worry about, an HOA architectural review can quietly add weeks that never show up in these timeline estimates. — Charlotte Pemberton, Senior ADU Design Consultant"
Market Context
Brentwood has a median home value of $760,000. Comparable renovation projects in this market typically add 25% to resale value.
Neighborhoods in Brentwood with the strongest home addition and resale value potential include Prewett Ranch, Garin Ranch, Shadow Lakes, Apple Hill, Sand Creek. Large-lot contemporary single-family homes ideal for detached ADUs with strong family-renter demand near Downtown Brentwood jobs.
Permit Process
Permit applications are reviewed by the Community Development Department, with a plan check timeline of approximately 12 weeks. Permit fees in Brentwood range from $4,000 to $15,000 depending on project scope.
Brentwood falls within Seismic Design Category D, which affects structural requirements for any new addition tying into the existing structure.
Local Financing Resources
Local Home Addition Lenders in Brentwood
These lenders offer HELOC, construction, and renovation loans for home addition projects in Contra Costa County. Compare terms before committing.
Has a Brentwood branch at 5601 Lone Tree Way and offers a specifically-named ADU Line of Credit (short-term HELOC): $10,000–$400,000, variable starting at 8.25% APR, 2-year interest-only draw / 20-year repayment, allows up to 125% CLTV and considers projected ADU rental income.
Visit Lender ↗Operates a Brentwood branch at 121 Sand Creek Rd and offers fixed-rate home equity loans and variable HELOCs nationwide for ADU/rehab financing, with fixed rates in a published range of approximately 8.24%–10.74% APR.
Visit Lender ↗Bay Area credit union serving the 925 area code (which includes Brentwood/Contra Costa County); offers California's-only HELOC limits with lines up to $200,000, up to 70% CLTV, 25-year term, no application or annual fees — usable for ADU construction or renovation on a primary residence.
Visit Lender ↗Northern California credit union offering construction loans of $50,000–$2,000,000 with future-value (as-completed) qualification — explicitly supports ADU builds by allowing qualification on the home's post-completion value rather than current value.
Visit Lender ↗National specialty ADU/renovation fintech that arranges loans through its credit-union partner network (including California credit unions); the RenoFi Loan is built around as-completed value, letting borrowers tap roughly 11x more equity than a traditional HELOC — accessible statewide including Contra Costa County (loans are arranged through partner CUs, not directly by RenoFi).
Visit Lender ↗Build With A Plan is not affiliated with these lenders. Always compare rates and consult a mortgage professional.
Local Build Partners
Vetted Home Addition Contractors in Brentwood
We draw the plans. These contractors build the addition. Independent — no referral fees paid or received.
Build With A Plan provides drawings only. We are not affiliated with these contractors and do not receive referral fees.
Free — No Obligation
What Will Brentwood Let You Add?
Setbacks, lot coverage, and height limits decide your addition before a single line is drawn. Send us the address and we’ll tell you what’s actually approvable — free, before you commit to a design.
- ✓Maximum footprint your lot and setbacks allow
- ✓Lot-coverage and height limits in Brentwood
- ✓Whether your addition triggers structural or energy upgrades
- ✓Realistic plan-check timeline for your project
- ✓A straight answer within 48 hours
Review My Project — Free
Takes 60 seconds. We'll deliver your personalized report within 48 hours.
Request Received
Your feasibility report is being prepared. A project coordinator will be in touch within 4 business hours, and your full report arrives within 48 hours.
Drawing Package Details
What's Included in Your Brentwood Home Addition Package
What You Get
What's in Your Brentwood Home Addition Package
One-time fee, no retainer, no hourly billing — your exact scope and price confirmed on a free call.
- ✓Site plan
- ✓Floor plans (existing + proposed)
- ✓All 4 elevations
- ✓Electrical plan
- ✓Title 24 energy compliance
- ✓PDF + DWG delivery
- ✓10 business day turnaround
- ✓Everything in Starter
- ✓Stamped structural drawings
- ✓Foundation plan
- ✓Roof framing plan
- ✓Window & door schedules
- ✓1 round of revisions
- ✓Everything in Standard
- ✓3D rendering
- ✓Cross-section details
- ✓Material specifications
- ✓HOA submission package
- ✓2 rounds of revisions
- ✓Priority 5-day turnaround
After You Order
Your Addition Drawings in 3 Steps
Submit Your Project Details
Share your property address, existing floor plan (if available), and the addition scope. We assign your project coordinator within 4 business hours.
We Draft Your Drawings
Our team designs your complete addition drawing set — engineered for Brentwood's building department requirements and CA CBC code. Delivered in 10 business days.
Submit to Your Building Dept
Download your complete package and submit to Community Development Department. We support plan check corrections at no extra charge.
Common Questions
Brentwood Home Addition FAQs
Do I need a permit for a home addition in Brentwood? +
Yes — any structural addition to your home in Brentwood requires a building permit. This applies to room additions, second-story additions, sunrooms, and attached garages. You'll need permit-ready drawings before the building department will accept your application. Our packages are formatted specifically for Brentwood's submittal requirements.
How much does a home addition cost in Brentwood? +
Home additions in Brentwood typically cost between $150–$400 per square foot depending on the scope, finishes, and structural complexity. A 600 sq ft addition ranges from $90,000 to $240,000. Second-story additions cost more than ground-floor extensions due to structural requirements. Contact us to discuss drawing package options for your project.
What drawings are required to permit a home addition in Brentwood? +
Brentwood's building department requires: a site plan showing the addition's footprint and setbacks, floor plans for all affected levels, all four exterior elevations, an electrical plan, and energy compliance (Title 24 in California). Structural plans stamped by a licensed engineer are required for any load-bearing elements — included in our Premium package.
How long does the permit process take for a home addition in Brentwood? +
Plan check in Brentwood typically takes 12 weeks for home additions. Additions with structural components may require additional review. Complete, code-compliant drawings significantly reduce correction cycles — each cycle adds 3–6 weeks. Our drawings are engineered to pass on the first submittal.
What setbacks apply to home additions in Brentwood? +
Brentwood enforces minimum setbacks from property lines for all additions: typically 4–5 ft side setbacks and 5 ft rear setbacks, though these vary by zoning district and lot size. Your addition must stay within the buildable envelope. Our site plan documents existing and proposed setbacks and flags any zoning variances required.
Do I need structural drawings for a home addition in Brentwood? +
Yes, for most additions. Any load-bearing walls, new foundations, second-story construction, or roof structure changes require stamped structural drawings from a licensed engineer. California's CBC (California Building Code) and seismic requirements make structural plans mandatory for most addition types. Our Standard and Premium packages include stamped structural drawings.
How much do home addition drawings cost in Brentwood? +
Our permit-ready home addition drawing packages for Brentwood include everything your building department requires — floor plans, elevations, structural, and energy compliance. Every package is engineered for CA code compliance and formatted for Brentwood's building department. 14-day money-back guarantee.
Will a home addition increase my home's value in Brentwood? +
In Brentwood, where median home values are approximately $760,000, a permitted home addition adds square footage that appraisers value as part of the home's gross living area. Return on investment varies by addition type — master suite additions, family room expansions, and additional bedrooms typically recoup 50–75% of project cost in appraised value in CA markets.
Can I add a second story to my home in Brentwood? +
Second-story additions are permitted in most Brentwood residential zones, subject to height limits and design review requirements. California generally requires ministerial permit approval, but some cities impose design compatibility or neighborhood compatibility review for second stories. Our drawings cover all levels including foundation upgrades, shear walls, and roof framing required for vertical additions.
Also Available in Brentwood
Adding an ADU instead? See our ADU design service.
Next Steps
Ready to Move Forward With Your Brentwood ADU?
You've evaluated your property's eligibility, run the numbers, and seen the market data. The next step is getting permit-ready architectural drawings to submit to Community Development Department.
Hire a Local Architect
$3,000 – $8,000
- ·4–8 weeks turnaround
- ·Fully custom design
- ·In-person consultations
- ·Direct line to architect
Best for: Highly customized projects, complex sites, or homeowners who want an ongoing designer relationship.
Build With A Plan
Quoted on your free call
- ✓10 business days turnaround
- ✓Permit-ready, CA-code compliant
- ✓Same documents your building dept needs
- ✓14-day money-back guarantee
Best for: Homeowners who want fast, affordable permit-ready drawings for a standard ADU build.
Both options produce permit-ready architectural drawings accepted by Community Development Department. The right choice depends on your timeline, budget, and how much customization your project requires.