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California / Concord / ADU builders

ADU builders in Concord, California

The short answer

23 licensed contractors building accessory dwelling units in Concord. Every licence below was checked against the California state register. Concord does not publish contractor names on building permits, so this list ranks on licence standing and pre-approved plans.

California Contractors State License Board, checked 2026-08-15
How to read this. Licence details come from the California Contractors State License Board and are dated on each profile. Permit counts reflect only those cities that publish the contractor's name on a building permit, so a builder with none listed may simply have worked where nothing is published. A city that pre-approves a plan has vetted the plan, not the builder, and does not endorse it. ADU Standards takes no payment for placement. Confirm any licence at cslb.ca.gov before you sign.

Ordered by what the records confirm

The list
1

Acton Construction Inc

Nearby permits Licence clear 34 years licensed Workers’ comp on file

CSLB #638333 · CAMPBELL

3

Quartz Construction

Licensed Licence clear 11 years licensed Workers’ comp on file

CSLB #1003436 · SAN JOSE

5

Imkat Construction Corp

Nearby permits Licence clear 4 years licensed Workers’ comp on file

CSLB #1094866 · SACRAMENTO

6

Jaws Construction Inc

Licensed Licence clear 8 years licensed Workers’ comp on file

CSLB #1037590 · BYRON

7

New Key Construction

Licensed Licence clear 7 years licensed Workers’ comp on file

CSLB #1050306 · WALNUT CREEK

8

Mana Construction Inc

Licensed Licence clear 7 years licensed Workers’ comp on file

CSLB #1043320 · VALLEJO

9

Green Group Roofing

Licensed Licence clear 7 years licensed Workers’ comp on file

CSLB #1051717 · CONCORD

10

Built Icon

Licensed Licence clear 6 years licensed Workers’ comp on file

CSLB #1060193 · CLAYTON

12

Hamilton Exteriors

Licensed Licence clear 5 years licensed Workers’ comp on file

CSLB #1078806 · CASTRO VALLEY

14

Type Five Inc

Licensed Licence clear 4 years licensed Workers’ comp on file

CSLB #1086540 · BERKELEY

15

Lecut Construction Inc

Licensed Licence clear 4 years licensed Workers’ comp on file

CSLB #1080990 · SAN JOSE

16

Nest Builders

Licensed Licence clear 2 years licensed No workers’ comp on file

CSLB #1117837 · MILL VALLEY

19

Ironnest Construction

Licensed Licence clear 1 years licensed Workers’ comp on file

CSLB #1130134 · SACRAMENTO

20

Optivest Build Inc

Licensed Licence clear 0 years licensed Workers’ comp on file

CSLB #1144711 · WALNUT CREEK

21

Royalty Builders Inc

Licensed Licence clear 7 years licensed No workers’ comp on file

CSLB #1048623 · WOODLAND HILLS

23

Sidex Siding & Decking

Licensed Suspended: no workers’ compensation on file 2 years licensed Workers’ comp on file

CSLB #1118697 · EL DORADO HILLS

What Concord charges

The city’s published schedule

Concord does not publish a fee schedule specific to accessory dwelling units. What follows is from its general schedule (current, adopted 2026-04-28), so expect to confirm the figures with the permit counter. These are city fees only. They do not include what a builder charges to design and build the unit.

Plan check
basis valuation-based table (General Building Valuation-Based Plan Review Fees)
detail $0.00 to $2,000: flat $83.93. $2,000.01 to $25,000.00: $83.93 base plus $9.93 per additional $1,000 or fraction thereof. $25,000.01 to $50,000.00: $312.32 base plus $23.78 per additional $1,000. $50,000.01 to $100,000.00: $906.82 base plus $18.76 per additional $1,000. $100,000.01 to $500,000.00: $1,844.82 base plus $13.70 per additional $1,000. Includes required plan review for all construction codes adopted by the City; includes one round of comments plus one back check. Additional plan review after back check is charged at the additional plan review hourly rate. Paid at time of application.
pre approved adu discount Pre-Approved ADUs will be assessed reduced plan review fees. These will be hourly fees for review of the site plan only.
as of 2026-04-28
Building permit
basis valuation-based table (General Building Valuation-Based Inspection Fees), plus an administrative fee
detail Inspection Fees: $0.00 to $2,000: flat $130.09. $2,000.01 to $25,000.00: $130.09 base plus $14.78 per additional $1,000. $25,000.01 to $50,000.00: $470.03 base plus $18.81 per additional $1,000. $50,000.01 to $100,000.00: $940.28 base plus $25.33 per additional $1,000. $100,000.01 to $500,000.00: $2,206.78 base plus $20.93 per additional $1,000. Administrative Fee: $70 + 0.000789V where V = valuation of construction, applied to each permit application or revision application, maximum $550, paid at time of application.
valuation method Construction Cost = (Square feet of construction) x (ICC Square Foot Construction costs), per the Construction Valuation Determination handout. Valuation is set by the Building Official.
as of 2026-04-28
School district fees
rate Not published by the City.
note Concord's ADU FAQ and fee documents do not address school facilities fees. Mt. Diablo Unified School District sets and collects.
Utility connections
water Contra Costa Water District, not a City fee.
sewer Central Contra Costa Sanitary District (Central San), not a City fee.
note There is a separate FAQ, 'What are the Engineering fees for an Accessory Dwelling Unit', at https://www.cityofconcord.org/Faq.aspx?QID=203 that was not retrieved.
Impact fees
under 750 language verbatim What kind of city fees do I have to pay to build an ADU? According to the current state law, cities are not allowed to impose impact fees on ADUs less than 750 square feet. You are required to pay plan check and permit fees to the building division, which are often a few thousand dollars.
source url https://cityofconcord.org/DocumentCenter/View/9200/ADU-FAQs-English-PDF
source document Accessory Dwelling Units - FAQs, Concord Development Code Section 18.200.180
rates for 750 plus Not published in the ADU materials or the Building Division fee schedule reviewed.
Worked example
verbatim You are required to pay plan check and permit fees to the building division, which are often a few thousand dollars.
precision qualitative only, no dollar figure

Concord fee scheduleFee schedule PDF

Common questions

How is this list ordered?

By what can be confirmed in public records: the number of accessory dwelling unit permits each contractor has on file in Concord, whether Concord has pre-approved their plans, and their licence standing with the California Contractors State License Board. No builder pays for position and none can request removal.

Are these builders licensed?

Every company listed has been matched to an active California contractor licence and its standing is shown on the card. California law requires a contractor to display its licence number in all advertising, and we check the number shown against the state register before publishing anything a company says about itself.

Why do some show no permit history?

Most California cities do not publish the contractor's name on a building permit. Where a city does not publish it, we cannot confirm completed work, so the card says the licence is verified and nothing more. Ask a builder directly for recent addresses and permit numbers you can look up.

What does it mean that Concord pre-approved a builder's plans?

Under Government Code section 65852.27 every California city must accept ADU plans for pre-approval and publish the resulting list. A pre-approved plan has cleared plan check in advance, which shortens permitting. It is an approval of the plan, not an endorsement of the company that drew it.

Companies we looked at and left out

Also considered

These came up when looking for ADU builders in Concord but did not meet the bar for the list above, usually because they do not advertise a California licence number, do not name Concord as an area they serve, or do not present accessory dwelling units as a service they offer. They are shown so the list above can be checked rather than taken on trust.

Four checks worth ten minutes.

Before you sign
  1. Look the licence up yourself at cslb.ca.gov. It takes under a minute and shows the current status, any suspensions, and the bond.
  2. Ask who carries workers’ compensation for the crew and for every subcontractor. A licensee with no employees may lawfully be exempt, but if someone is hurt on your property you can end up treated as the employer.
  3. Ask for two recent permit numbers in any city, then look them up. A builder who has done the work can produce them immediately.
  4. Get the price in writing against a drawing set. A published starting price is for a base model and rarely includes site work, utilities, or Concord fees.