Williamson Const
Home addition contractor based in Los Angeles. Licensed since 1984.
- License active
- Workers' comp on file
5 jobs on Los Angeles permits, 2025 to 2026: 4 home additions, 1 remodel. 181st most addition permits of 357 contractors in Los Angeles.
What the public records show
From the state's license records and the city's permits, one question at a time.
| Question | Records show | Mark |
|---|---|---|
| Licensed? | License 451421, active in the state's records on Sep 23, 2026General buildingNo complaints or citations on the board's public record. | Checks out |
| Workers' comp? | Workers' comp policy on file with the stateThis covers their crew if someone is hurt. It is not insurance for your home. | On file |
| In business? | Licensed since 1984 | |
| Jobs on record | 5 jobs on Los Angeles permits, 2025 to 2026: 4 home additions, 1 remodel181st most addition permits of 357 licensed contractors in Los Angeles. That counts jobs, not quality.Our Los Angeles permit records cover September 2023 to September 2026. |
Records: the state license board and City of Los Angeles permits.
State license board record
Last checked Oct 4, 2026. This may have changed. Check it on CSLB.
No complaints or citations on the board's public record.
Source: California Contractors State License Board, checked Oct 4, 2026. Look up license 451421 on CSLB
Cost and timing
All addition jobs in Los Angeles: $38,000 to $120,000
Half of 10,836 city permits list an amount in this range. Permit amounts are often lower than what you pay.
- Second-story additions in Los Angeles: $75,000 to $200,000 (858 permits)
- Garage additions in Los Angeles: $48,000 to $110,000 (3,411 permits)
How to read this range
Contractors write a job value on the permit form, and the city uses it to set the permit fee. It is not the contract price, and it is often lower than what you pay. A quarter of the permits list less than this range, and a quarter list more. Use it to see if a quote is in the normal range.
Permit value (not a price)
Their typical permit lists $77,500 (half list more, half less)
That is the figure written on the permit form, which can be far from what you pay. What addition jobs cost in Los Angeles.
Get 2 or 3 written quotes.
Permit timeline
Across Los Angeles, a addition permit stays open about about 13 months, from permit to final inspection
This is not how long the crew works at your home: most of it is waiting for the inspection. Ask them how many days the work takes. Waiting for the permit adds about about 4 months. How long addition jobs take.
Track record
Where they work most
- 900451 job
- 900661 job
- 902301 job
- 900341 job
- 900641 job
Jobs by kind of work
Latest jobs
Permit values are what the contractor wrote on the permit form, not what the owner paid.
| Date | Work | ZIP | On the permit form |
|---|---|---|---|
| Sep 17, 2026 | AdditionAddition and interior alteration to (E) single family dwelling | 90045 | $85,000 |
| Jul 21, 2026 | AdditionRemodel (e) SFD and (n) first floor addition | 90066 | $100,000 |
| Jun 2, 2026 | RemodelStructural remodel of an (e) attached garage | 90230 | $37,000 |
| Apr 26, 2025 | AdditionSingle story addition & interior remodel | 90034 | $30,000 |
| Mar 29, 2025 | AdditionAddition and interior remodel to (E) SFD | 90064 | $70,000 |
What to ask before you hire
About Williamson Const
- Ask what the warranty covers and for how long, in writing.
Worth asking any home addition contractor
- Can you show me proof of liability insurance and your bond?
- Do you handle the plans and engineering, or do I hire them?
- Who will run the job day to day, and who are the subcontractors?
- Who pulls the permits, and what is the payment schedule?
Get a quote from Williamson Const
Five quick questions. We pass your request to Williamson Const.
Request for Williamson Const
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We pass it to Williamson Const. Replies usually come within a few days.
Your job room keeps the request, your photos and every reply in one place, with an assistant that checks prices against city permits. Keep its link: it is the key to your job.
Open your job roomMore home addition contractors near 90045 and 90066
- Local Construction Remodeling
- American Patio Masters Inc
- Williams Christopher
- South Coast Construction and Development
- Southwest Construction and Home Improvement
- Stay Forever Construction Corporation
See all 357 home addition contractors in Los Angeles, ranked by jobs
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