What's the difference between permit drawings for new construction and an addition?

New construction starts from a blank site: every dimension, assembly, and code compliance item is established without anything to reference. An addition requires existing conditions to be documented first, then the proposed work is drawn and dimensioned against that existing baseline so the plan checker can verify how new construction ties into what's already there.

Do commercial permit drawings require anything residential drawings don't?

Yes. Commercial and mixed-use projects typically require occupancy classification, accessibility compliance, fire and life safety documentation, and MEP coordination that residential projects usually don't trigger. Tenant improvements add their own layer of build-out-specific requirements.

Can you get a permit for work that was never permitted?

In most jurisdictions, yes, through an after-the-fact or legalization permit process. It starts with as-built documentation of the existing unpermitted work, followed by a compliance review to identify what does and does not meet current code, and a permit application addressing any required corrections.

What is required for an after-the-fact permit?

Requirements vary by jurisdiction, but most require as-built drawings of the unpermitted work, a code compliance review, and sometimes an inspection to verify the work meets structural and life safety standards. Some jurisdictions require partial demolition of work that cannot be brought into compliance.

Do remodel permit drawings need a structural engineer?

Only if the remodel affects load-bearing elements: removing or relocating a wall, adding an opening, or changing the roof or floor structure. Cosmetic remodels that don't touch structural elements typically don't require engineering.

How detailed do permit drawings need to be?

Detailed enough for the plan checker to verify code compliance and for a contractor to build from without guessing. That generally means complete dimensions, clearly distinguished existing and proposed work, cross-referenced details, and schedules that match what's shown on the plans.

What's actually different between commercial and residential drawings?

Commercial drawings carry occupancy classification, accessibility, and fire and life safety requirements that most residential projects never trigger, along with MEP coordination that's typically more involved. A residential-focused drafter taking on a commercial tenant improvement is a common source of correction comments.

Do I need ADA compliance drawings for a commercial project?

In most cases, yes, if the space is open to the public or employs people outside the owner's household. ADA and accessibility documentation is typically required as part of the commercial drawing set, not an optional add-on.

What drawings do I need for something as simple as a bathroom remodel?

It depends on scope and jurisdiction, but a non-structural bathroom remodel typically needs, at minimum, an existing and proposed floor plan and any plumbing or electrical changes noted. Moving walls or fixtures that affect structure or egress adds requirements from there.

Permit Drawings

Permit drawings for new construction, additions, remodels, and after-the-fact permits.

From a ground-up commercial building to a single-room addition to legalizing work that was never permitted, every project needs a drawing set built to what the building department actually requires. CADTRI produces permit-ready drawings for residential and commercial projects at every stage.

What's in a Permit Drawing Set

The sheets a plan checker actually reviews.

The exact scope varies by project, but nearly every permit drawing set is built from the same core components. What changes between a new construction set and an after-the-fact permit is how much of it has to be documented from an existing condition versus designed from scratch.

Site Plan

Property lines, setbacks, existing and proposed structures, easements, and site improvements drawn to the jurisdiction's required scale.

Floor Plans

Existing and proposed layouts with complete dimensions, room labels, door and window locations, and any structural elements shown.

Exterior Elevations

Every building face showing proposed materials, heights, window and door placement, and any changes to the existing exterior.

Building Sections and Details

Cross-sections and construction details showing how assemblies go together, required for framing, insulation, and waterproofing review.

Schedules and Notes

Door, window, and finish schedules along with the general and code compliance notes referenced throughout the set.

Code Compliance Documentation

Zoning conformance, energy compliance, and accessibility documentation coordinated with the drawings, not produced as an afterthought.

By Project Type

New construction, additions, remodels, and after-the-fact.

What a permit drawing set needs to show depends heavily on what already exists on the property, or doesn't.

New Construction
Ground-up residential and commercial projects require a complete drawing set built from a blank site: site plan, full floor plans, elevations, sections, structural coordination, and all applicable code compliance documentation. Nothing exists to reference, so every dimension and assembly is established from scratch.
Additions
Room additions, second-story additions, and building expansions require existing conditions drawings paired with the proposed new construction, dimensioned and detailed so the plan checker can see exactly where new work ties into the existing structure.
Remodels
Interior remodels and renovations focus on existing floor plans and proposed layout changes, along with any code triggers the renovation activates: egress, accessibility, or energy compliance, depending on the scope and occupancy.
After-the-Fact Permits
Work completed without a permit needs as-built documentation of the existing condition before a legalization application can move forward. We measure and draw the unpermitted work as built, then prepare the compliance documentation needed to bring it into the permit record.

Requirements Matrix

What each project type actually requires.

The four project types side by side: whether existing conditions documentation is required, whether structural engineering is triggered, and what that means for the timeline.

Permit Drawing Requirements by Project Type

Project Type	Existing Conditions	Structural Engineering	Timeline Impact
New Construction	Not required — blank site	Required for the full structural design	Longest: full design plus full plan check
Additions	Required, to tie new work to existing	Required if any load-bearing element is affected	Moderate: existing conditions plus addition design
Remodels	Required only for the areas being altered	Only if load-bearing elements change	Fastest of the four, when non-structural
After-the-Fact Permits	Always required — as-built baseline	Required if unpermitted work affected structure	Longest: as-built documentation plus compliance review

Residential and Commercial

Two building types, two different scopes.

The project type sets the drawing structure. The building type sets how much code compliance documentation rides alongside it.

Residential

Single-family homes, ADUs, additions, and remodels typically require a site plan, floor plans, elevations, sections, and energy compliance documentation. Structural engineering is required for additions and any work affecting the load path.

Home Addition Packages

Commercial

Commercial and mixed-use projects carry additional occupancy classification, accessibility, and fire and life safety requirements. MEP coordination, exiting analysis, and tenant-improvement-specific scope are typically part of the drawing package.

Tenant Improvement Packages

Permit Drawing Services We Provide

A drawing package for every scope.

From a full new-construction set to as-built documentation for a legalization application, these are the drawing-specific services CADTRI delivers most often.

Common Pitfalls

What makes a permit drawing incomplete.

Most correction comments on the drawings themselves, as opposed to administrative or zoning issues, trace back to one of these gaps.

Missing Dimensions

Plans without complete dimension strings force the plan checker to guess, a fast path to a correction comment.

Existing vs. Proposed Not Distinguished

Renovation and addition drawings that don't clearly differentiate what's existing, new, and demolished.

Unreferenced Details

Callouts on a plan that don't point to an actual detail or section drawn elsewhere in the set.

Missing Structural Callouts

Headers, beams, and connections required by the scope but not shown or cross-referenced to the structural set.

Incomplete Schedules

Door, window, and finish schedules that don't match what's actually shown on the plans.

No Egress Analysis

Missing occupant load, exit width, or travel distance calculations on projects where occupancy or layout changes trigger the requirement.

Scale and Sheet Size Errors

Drawings not produced at the scale or sheet size the jurisdiction requires for the project type.

Missing Existing Conditions

After-the-fact and remodel projects submitted without a documented existing condition baseline to compare the proposed work against.

Glossary

Drawing sheet terms, defined.

The names of the sheets that make up a permit set, and what each one is actually for.

Site Plan: The sheet showing property lines, setbacks, and existing and proposed structures. Often the sheet that decides whether a project can be permitted at all.
Floor Plan: A scaled top-down view of a building level showing walls, rooms, dimensions, and door and window locations.
Elevation: A straight-on view of a building face showing height, materials, and window and door placement as seen from outside.
Section: A vertical cut through the building showing how floors, walls, and roof assemblies stack and connect.
Title Block: The sheet border identifying the project, scale, date, and revision history. Missing or inconsistent title blocks are a common source of delay.
Code Analysis Sheet: The sheet documenting how the project meets applicable building and zoning code, referenced throughout the set.

Frequently Asked

Permit drawings, explained.

What's the difference between permit drawings for new construction and an addition?: New construction starts from a blank site: every dimension, assembly, and code compliance item is established without anything to reference. An addition requires existing conditions to be documented first, then the proposed work is drawn and dimensioned against that existing baseline so the plan checker can verify how new construction ties into what's already there.
Do commercial permit drawings require anything residential drawings don't?: Yes. Commercial and mixed-use projects typically require occupancy classification, accessibility compliance, fire and life safety documentation, and MEP coordination that residential projects usually don't trigger. Tenant improvements add their own layer of build-out-specific requirements.
Can you get a permit for work that was never permitted?: In most jurisdictions, yes, through an after-the-fact or legalization permit process. It starts with as-built documentation of the existing unpermitted work, followed by a compliance review to identify what does and does not meet current code, and a permit application addressing any required corrections.
What is required for an after-the-fact permit?: Requirements vary by jurisdiction, but most require as-built drawings of the unpermitted work, a code compliance review, and sometimes an inspection to verify the work meets structural and life safety standards. Some jurisdictions require partial demolition of work that cannot be brought into compliance.
Do remodel permit drawings need a structural engineer?: Only if the remodel affects load-bearing elements: removing or relocating a wall, adding an opening, or changing the roof or floor structure. Cosmetic remodels that don't touch structural elements typically don't require engineering.
How detailed do permit drawings need to be?: Detailed enough for the plan checker to verify code compliance and for a contractor to build from without guessing. That generally means complete dimensions, clearly distinguished existing and proposed work, cross-referenced details, and schedules that match what's shown on the plans.
How much do permit drawings cost?: Most residential permit drawings cost between $500 and $8,000, with the final number driven by project type, jurisdiction, and how much existing-conditions documentation is required. Commercial and tenant improvement drawings typically run higher due to added code compliance scope.
What's actually different between commercial and residential drawings?: Commercial drawings carry occupancy classification, accessibility, and fire and life safety requirements that most residential projects never trigger, along with MEP coordination that's typically more involved. A residential-focused drafter taking on a commercial tenant improvement is a common source of correction comments.
Do I need ADA compliance drawings for a commercial project?: In most cases, yes, if the space is open to the public or employs people outside the owner's household. ADA and accessibility documentation is typically required as part of the commercial drawing set, not an optional add-on.
What drawings do I need for something as simple as a bathroom remodel?: It depends on scope and jurisdiction, but a non-structural bathroom remodel typically needs, at minimum, an existing and proposed floor plan and any plumbing or electrical changes noted. Moving walls or fixtures that affect structure or egress adds requirements from there.

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Permit drawings for new construction, additions, remodels, and after-the-fact permits.

The sheets a plan checker actually reviews.

New construction, additions, remodels, and after-the-fact.

New Construction

Additions

Remodels

After-the-Fact Permits

What each project type actually requires.

Two building types, two different scopes.

Residential

Commercial

A drawing package for every scope.

What makes a permit drawing incomplete.

Drawing sheet terms, defined.

Permit drawings, explained.

Go deeper on permit drawings.

What Drawings Do You Need for a Building Permit?

How to Read a Permit Drawing Set

Commercial vs. Residential Drawings

ADA Compliance Drawings

How Much Do Permit Drawings Cost?

What Is a Code Analysis Sheet?

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Permit guides, code updates, and project insights.