Does Your Altadena Rebuild Need a Grading Plan?

LA County has been changing requirements every week since the Eaton Fire. If you have been trying to rebuild in Altadena, you already know this. Contractors, civil engineers, and homeowners are all trying to figure out the same thing: what does LA County actually require to issue a permit?

We have been in the middle of this since day one. Here is what we have learned.

Drainage Plan vs. Grading Plan: What Is the Difference

A drainage plan handles water flow, minor grading, and keeping slopes at reasonable angles. A grading plan is full civil engineering. It is required when a site has more complex work happening outside the building footprint.

The difference matters for timeline and coordination. But here is the thing. LA County has not published clear thresholds for what triggers a grading plan on fire rebuilds specifically. We have all been figuring this out as we go.

What We Have Learned About What Triggers a Grading Plan

Through working through plan check with LA County DPW week after week, we have a better idea of what pushes a project into grading plan territory. Most fire rebuild applications are going through the One-Stop Permit Centers, which has been changing how things move.

When a Full Grading Plan May Be Required

You likely need a grading plan when:

• Large cuts or fills beyond the building footprint
• Retaining walls beyond the building footprint
• Driveway requiring tall retaining walls
• Rear hillside needing slope stabilization

When a Drainage Plan May Be Enough

If the work stays within or under the building footprint and we can keep slopes at 5:1 or gentler and blend into existing grades, a drainage plan is often all you need.

In some cases, a hydrology report is also required to document pre-fire drainage patterns and show LA County how post-development drainage compares to pre-fire conditions.

LA County has not made this official. The rules have been shifting since early 2025. But this is what we have seen work in practice.

How We Approach Each Site

We look at your specific lot and your proposed structure. We try to design in a way that keeps you in drainage plan territory when possible. Keeping slopes at 5:1 or gentler and blending into existing grades is the goal.

If your site needs more than that, we will tell you upfront. We are not going to tell you that you need a full grading plan when a drainage plan will get your permit approved.

Contractors have been coming to us for this reason. They have projects in Altadena and they need a civil engineer who can give them a straight answer about what the site actually needs. That is what we do.

Questions to Ask Before You Start

Ask your civil engineer these questions before you commit:

• Can we design this to stay within drainage plan requirements?
• What on my specific lot would trigger a grading plan?
• How has LA County been handling fire rebuild plans recently?

If your civil engineer cannot answer these questions, that tells you something.

Start a Conversation About Your Altadena Lot

We are still learning alongside LA County as they continue to shift requirements. When you talk to us, you are talking to people who are in the thick of it every week.

If you have a lot in Altadena and you are trying to figure out what your rebuild needs, start a conversation. We will look at your specific site and tell you what you actually need.