What Is the 10% Rule?
The 10% rule is one of the most important � and most misunderstood � concepts in Los Angeles permitting. Simply put, it states that modifications to an existing system can qualify for express permit processing (5 days) as long as the changes don't exceed 10% of the existing system.
Exceeding this threshold means your project requires a regular plan check permit, which can take approximately 3 months � a significant delay for any construction project.
How the 10% Rule Works in Practice
Here are practical examples of how the 10% rule applies:
- Electrical: Adding circuits that represent no more than 10% of your existing panel's capacity
- Plumbing: Adding fixtures that don't exceed 10% of your current fixture count
- HVAC: Modifying ductwork that doesn't exceed 10% of the existing system
- Building: Modifications that don't exceed 10% of the existing structure's elements
Common Mistakes That Trigger Rejections
The most frequent 10% rule violations we see in Los Angeles include:
- Underestimating the scope of modifications � homeowners often don't realize how quickly changes add up
- Not accounting for previous permitted work that already used part of the 10% allowance
- Misunderstanding what counts as "existing" versus "new" in the calculation
- Applying the rule incorrectly across multiple systems simultaneously
How to Stay Within the 10% Threshold
Our recommendation is to have a professional review your project scope before applying. We'll calculate your 10% threshold accurately and ensure your application qualifies for the 5-day express process instead of the 3-month regular permit. If your project exceeds 10%, we can help you determine the most efficient plan check approach.
Concerned about the 10% rule for your project? Contact us for a free evaluation.