Danville’s permit triggers
| Trigger | Example |
|---|---|
| More than 3 ft of retained soil | A 4 ft wall along a sloped side yard |
| Vehicle traffic surcharge | A wall along a driveway or parking pad |
| Load from nearby structures | A wall near a house, pool or garage |
| Sloping site | Ground continues to rise above the wall |
| Uphill tiered wall | A terrace whose upper wall loads the lower one |
Replacing old wood walls
Timber and railroad-tie walls along Danville side yards and slopes are reaching the end of their life (wood walls last about 10–40 years per HomeGuide). Public permit records include a 6-foot CMU wall replacing a wood wall in Danville at a $7,000 valuation (permit records). At 6 feet a replacement is over the Town’s threshold, so plan for a permit. See repair vs. replacement.
Replacing a failing wood wall? A local contractor can price removal and the new wall together.
Alamo, Blackhawk and Diablo
Outside town limits, the County’s exemption covers walls not over 3 feet from the top of the footing, as long as the ground below doesn’t slope down more than 1:10 and the wall doesn’t support a surcharge or a slope steeper than 1:2; walls on fill need a grading permit (County retaining walls). Blackhawk adds HOA architectural review, so build HOA approval into the schedule.
Trees
Danville regulates removal of certain trees; check the Town’s tree removal requirements before excavating near large oaks.
Costs: cost guide. All rules side by side: permits by city.
Danville-area questions
Do I need a permit for a retaining wall in Danville?
Yes, if the wall supports more than 3 feet of soil, or is loaded by vehicle traffic, nearby structures, a sloping site or an uphill tiered wall (Town of Danville).
Are Alamo, Blackhawk and Diablo under Danville’s rules?
No. They’re unincorporated, so the County’s rules apply: a permit above 3 feet measured from the top of the footing, plus slope and surcharge conditions, and a grading permit for walls on fill. Blackhawk homeowners also need HOA architectural review.
Sources
- Town of Danville: Retaining wall permit
- Town of Danville: Grading permit
- Contra Costa County: Retaining walls (PDF)
- HomeGuide: Retaining wall cost (2026)
- Contra Costa County ePermits (permit records)
- Blackhawk HOA architectural review
- Town of Danville: Tree removal requirements (PDF)
Checked October 2026. Rules and prices change; confirm with the agency or a contractor before you build.