San Diego, California Sep 14, 2026 (Issuewire.com) - Streamline Design & Permitting, a pre-construction services firm specializing in ADU design in San Diego, residential drafting, and building permit assistance, today released an analysis of cost and timeline patterns it has observed among residential construction projects across San Diego, Los Angeles, Riverside, and Orange counties. The analysis draws on the firm's internal project records alongside publicly available data from local permitting agencies and industry research organizations.

Pre-Construction Costs and Permit Review Timelines

According to the firm's analysis, the pre-construction phase of a residential project, including site assessment, architectural drafting, Title 24 energy compliance, and permit preparation -- typically represents 3-4 percent of total project cost. As an illustrative example, for an ADU or home addition budgeted at $400,000, that range would translate to approximately $12,000-$16,000 in drafting and permitting fees.

The City of San Diego's Development Services Department (DSD) reviews residential drawing submittals for code compliance through a plan check process. Per DSD's published review policy, each round of plan check is intended to address only the corrections identified in the prior review or changes initiated by the applicant, meaning incomplete or non-compliant drawings can result in additional correction cycles before a project reaches approval. 

Under SB 543, which took effect January 1, 2026, local agencies are required to complete permit reviews within 60 days of a complete application. The 60-day clock begins only once an application is deemed complete; incomplete submittals reset the review period.

Industry Cost Data on Pre-Construction Planning

The Construction Industry Institute (CII), a research consortium of owners, contractors, and academic institutions focused on construction performance, developed the Project Definition Rating Index (PDRI) to measure how thoroughly a project's scope is defined before design and construction begin. Research using the PDRI has found that well-defined projects can come in roughly 2 percent under budget on average, while poorly defined projects have exceeded their budgets by an average of 14 percent (Collins et al.). Using the same $400,000 example, that gap is roughly equivalent to a $64,000 difference in outcome between a well-defined and a poorly defined project. 

Taken together, the DSD and CII data point to the same underlying factor: the completeness of a project's drawings and scope before submission, rather than any single design firm's involvement, is what most consistently affects review timelines and budget outcomes. Streamline Design & Permitting also reported a 30 percent reduction in its own ADU plan approval times earlier this year, which the firm attributes to more thorough pre-submittal documentation. 

"Our data shows a consistent pattern: the completeness of drawings submitted for plan check has a measurable effect on how many review cycles a project goes through," said Devin Way of Streamline Design & Permitting. "We're sharing this analysis so homeowners have accurate figures when planning an ADU or remodel project."

About Streamline Design & Permitting

Streamline Design & Permitting is a San Diego County pre-construction services firm specializing in accessory dwelling units, residential additions, whole-house remodels, code compliance documentation, and commercial tenant improvements. The firm serves property owners across San Diego County, Los Angeles County, southern Orange County, and southwestern Riverside County.

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