If your property has brush management overlays, fire access constraints, environmentally sensitive land, steep slopes, or unusual easements, you may hear your ADU designer recommend a Preliminary Review with the City before moving into full construction documents.
A Preliminary Review is not about approval. It is about deciding whether to resolve high-risk issues now or during plan check.
In some cases, it materially reduces redesign risk and sharpens the path to permit. In others, it just accelerates expenses without improving the outcome. When feasibility is grounded in construction realities, it becomes clear whether Preliminary Review will actually move the needle. This article explains:
- What a Preliminary Review is
- What it costs
- When it makes sense and when it does not
- How it fits into the SnapADU feasibility process
If you are evaluating whether to pursue one, this will help you decide with clarity.
What Is a Preliminary Review?
In the City of San Diego, a Preliminary Review is a written feedback process conducted with specific City departments before full ADU permit submittal.
It is not a permit application. It is not an approval. It is not binding.
Instead, it is a structured way to submit plans and written questions to one or more City departments and receive formal written comments about potential issues.
Relevant departments often include:
- Fire
- Brush Management
- Development Engineering
- Environmental / ESL
- Landscape
You can review the City’s formal description here: City of San Diego Preliminary Review Process
The goal is to identify major constraints early, particularly those that could affect:
- ADU location on the lot
- Required setbacks beyond standard zoning
- Brush management zones
- Fire access requirements
- Impacts from environmentally sensitive land
Does a Preliminary Review Lock in Approval?
No. It provides written feedback based on the information submitted at that time. If the design changes materially, the feedback may change. It reduces uncertainty. It does not eliminate it. No City process is entirely without risk.
Preliminary reviews allow us to obtain written feedback from city planners, providing more clarity on potential hurdles and ensuring our approach aligns with their expectations. By engaging early, we can more readily work collaboratively to address concerns before investing in a full set of construction documents (CDs).
So while a Preliminary Review does not guarantee approval, it can sometimes streamline later plan check by resolving major placement or fire concerns before full submittal. When departments have already weighed in on high-risk issues, subsequent review cycles may be more focused and efficient.
Virtual Appointments vs. Preliminary Review
Sometimes we schedule a Virtual Appointment with Planning, Engineering, Fire, Brush Management, or Landscaping before submitting a Preliminary Review.
Important distinction is that a Virtual Appointment is informal guidance. A Preliminary Review produces written feedback.
The virtual appointment can help us decide:
- Whether a Preliminary Review is necessary
- Whether multiple departments must be reviewed
- Whether the City will require additional drawings before commenting
But virtual guidance is not binding, and the helpfulness of the call can vary greatly. The city notes that virtual meetings are for informational purposes only.
What Does a Preliminary Review Cost?
There are two cost components:
- SnapADU coordination fee: Typically $500 for a single discipline review. This is for our team to handle pulling together the submission and questions for the city.
- City departmental review fees: Approximately $1,500 per department. So if Fire, Engineering, and Landscape are all required, City fees alone may total around $4,500.
Notable point to understand: most of this same feedback would be issued during normal plan check at no additional departmental cost.
So the key question becomes: are we paying upfront to reduce risk, or are we paying to get the same information earlier?
How Long Does a Preliminary Review Take?
In most San Diego jurisdictions, Preliminary Review comments are issued within 20-30 days of submission.
That timeline can vary depending on the number of departments reviewing, staff workload, whether additional information is requested, and the complexity of the site.
It is important to factor this into overall project sequencing. While a Preliminary Review can reduce the likelihood of redesign later, it does introduce an additional review step that typically adds about one month to the front end of the project timeline.
As with cost, the decision comes down to whether that month meaningfully improves the clarity of placement, fire compliance, or environmental constraints before advancing.
Do Other Cities Offer Preliminary Reviews?
It depends. Preliminary Review processes vary significantly by municipality and by the local fire district.
Certain jurisdictions offer a clearly defined, fee-based preliminary review program similar to the City of San Diego’s written feedback model. Many jurisdictions in San Diego County do not have a formal Preliminary Review program at all.
Instead, they may offer:
- Informal staff meetings
- Counter appointments
- Email guidance
- Or no pre-review option whatsoever
In those cases, the first formal feedback typically comes during standard plan check.
Even if a city does not offer a formal preliminary review, the fire authority having jurisdiction may operate independently. For example, a city may handle zoning and planning. A separate fire district may review fire access, hose pull distances, or brush management requirements. Some fire districts allow early consultation. Others only review during formal permit submittal.
Strategic Considerations
Before electing a Preliminary Review, ask:
- Would City comments meaningfully change layout or cost?
- Are we trying to reduce risk, or are we trying to reduce anxiety?
- Does sequencing it first avoid downstream wasted effort?
- Does information from the preliminary review affect your next course of action?
The right answer depends on your lot specifics, as well as your own risk tolerance.
When a Preliminary Review Makes Sense
We typically recommend one when:
- The lot contains Environmentally Sensitive Land
- There is significant slope
- The site is in a high fire severity zone
- Brush Management overlays are complex
- The ADU location is tight and requires precision
- There are unclear access constraints
- Easements appear to restrict placement
In these situations, a Preliminary Review can prevent a material redesign later.
When We Often Recommend Skipping It
We frequently advise proceeding without a Preliminary Review when:
- The lot is flat and unconstrained
- There are no ESL overlays
- Brush management zones are straightforward
- The ADU placement is clearly compliant
- Risk of relocation is low
In these cases, it may be more efficient to advance into Construction Documents, submit for full permit, and simply receive agency comments through normal plan check.
Yes, this carries some risk. But often that risk is small relative to the added cost and time of a Preliminary Review.
Real Example: When We Recommended Skipping Preliminary Review
A homeowner recently asked whether we should pursue a Preliminary Review before moving into Construction Documents due to concerns about potential environmentally sensitive vegetation, fire review, slope, easements.
The core question was simple: What is the likelihood that plan check would force a footprint reduction or redesign?
In this case, the proposed ADU footprint sat entirely within existing flatwork, meaning construction would not impact native vegetation or environmentally sensitive habitat.
So based on current site conditions, the fact that the structure avoided natural grade, and prior experience navigating similar reviews, we assessed the likelihood of a material redesign as very low. Because of that, our recommendation was to proceed directly into Construction Documents and obtain formal agency feedback through standard plan check rather than pay for a Preliminary Review.
A formal Preliminary Review would have required separate departmental fees for Fire, Engineering, and Landscaping. In this scenario, that meant approximately $4,500 in City fees for information that would surface during normal plan check at no additional cost.
In short: The risk of redesign was low. The added cost was certain. So we advanced at measured risk.
How Preliminary Reviews Fit Into the Feasibility Process
At SnapADU, feasibility is always construction based… because we want you to be able to build the ADU that you design. So we start with assessing:
- Buildable envelope
- Fire access
- Utility routing
- Grade and slope
- Easements
- Brush and ESL overlays
If a property triggers concerns in those areas, we may recommend sequencing the project like this:
- Produce an initial Feasibility Report
- Submit for Preliminary Review with relevant departments
- Incorporate City feedback
- Revise feasibility before advancing to survey, utility mapping, and full design
This sequencing helps avoid paying for detailed design work that might need to move if Fire or Brush requires adjustments.
How This Connects to Feasibility and Fire Requirements
If you are reading this because of brush or fire overlays, you may also want to review:
- Our article on ADU Feasibility Studies in San Diego
- Our article on ADU Fire Requirements in San Diego
Preliminary Reviews are not a substitute for feasibility. They are a tool within it.
A Preliminary Review is a risk management tool. It can provide earlier written clarity, reduce chance of late-stage redesign, and increase confidence before investing in construction documents
It also adds cost and adds time, plus can duplicate plan check feedback. For constrained lots, it can be valuable. For straightforward lots, it is often unnecessary. So the decision should be strategic, not automatic.
If you are unsure which category your property falls into, the right first step is a construction based feasibility review that evaluates real constraints before money is spent in the wrong order.
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