Who Is Responsible for What?
Manufacturer vs. Contractor vs. Owner
Prefab projects can become confusing for a simple reason: there may be several companies involved, and every company is responsible for a different piece.
The manufacturer builds the house.
The licensed contractor builds the site.
Someone prepares the local permit package.
Someone designs the foundation.
Someone arranges transportation.
Someone hires the crane.
Someone connects the utilities.
Someone responds when the building department issues corrections.
And when nobody clearly owns one of those jobs, the owner often discovers that it belongs to them.
The biggest risk in many prefab projects is not that nobody can do the work. It is that everybody assumes somebody else is doing it.
There Is No Universal Division of Responsibility
Do not assume every prefab company operates the same way.
One manufacturer may sell only the factory-built product.
Another may offer design, permitting, foundation, delivery, installation, and site work through affiliated or local contractors.
A dealer may sit between you and the manufacturer.
A licensed general contractor may take responsibility for nearly the entire completed project.
Or the owner may separately hire five or six different parties.
Any of those structures can work.
The important thing is knowing which one you actually have.
The contract - not the sales pitch - should tell you where each company's responsibility begins and ends.
The Manufacturer: Usually Responsible for the Factory Product
For California Factory-Built Housing, the manufacturer is responsible for producing the factory-built unit or components in accordance with the approved factory plans and applicable approval process.
HCD explains that FBH design and construction are inspected and approved through HCD-certified third-party agencies, and qualifying FBH offered for sale to first users in California must bear an HCD insignia before shipment.
Depending on the product and contract, the manufacturer's scope may include:
Factory structural construction.
Factory-installed electrical systems.
Factory-installed plumbing.
Factory-installed mechanical systems.
Insulation.
Windows and exterior doors.
Roof components.
Interior finishes.
Cabinetry and fixtures.
Factory quality-control procedures.
Approved factory plans and documentation.
Required HCD insignia for California FBH.
But do not assume the manufacturer is responsible for the property simply because it manufactured the house.
The manufacturer can deliver a code-compliant factory product without delivering a completed code-compliant project on your parcel.
What the Manufacturer May Not Be Responsible For
Unless the contract specifically says otherwise, the manufacturer may not be responsible for:
Zoning feasibility.
Local planning approval.
The site plan.
Surveying.
Grading.
Site-specific foundation construction.
Septic.
Sewer connection.
Well or water connection.
Electrical service upgrades.
Driveways.
Fire access.
Retaining walls.
Drainage.
Transportation beyond a stated delivery point.
Crane/set.
Onsite assembly.
Local inspections.
Site restoration.
Some manufacturers provide many of these services.
Some provide almost none.
That difference can explain tens of thousands of dollars between two proposals.
The Manufacturer's Plans Are Not the Entire Permit Set
This is one of the most important handoffs to understand.
The factory may provide approved building plans for the manufactured portion of the project.
But HCD states that the approved plans associated with the FBH unit must be submitted to the local agency, and installation remains subject to local building-department inspection.
The local permit package may still need:
Site plan.
Foundation plans.
Site-specific structural details.
Grading information.
Drainage.
Utility plans.
Energy documentation where applicable.
Fire-access information.
Septic or sewer information.
Other jurisdiction-specific documents.
Someone has to combine the factory information with the property information.
Factory plans describe the building. Local plans describe the project.
The Licensed General Contractor: Usually Responsible for the Work They Contract to Perform
A licensed general contractor may become the bridge between the factory and the property.
Depending on the contract, that can include:
Site preparation.
Foundation.
Utility trenches.
Onsite assembly.
Roof or siding completion.
Mechanical connections.
Electrical connections.
Plumbing connections.
Stairs, decks, and landings.
Driveway work.
Drainage.
Coordination of subcontractors.
Inspection coordination.
Correction work.
Cleanup.
But the contractor is responsible for the scope they actually agreed to perform.
If the contract excludes grading, sewer, utility-company work, crane service, permit preparation, or landscaping, those items do not magically become included because the contractor is the general contractor.
California CSLB requires home-improvement contracts over the statutory threshold to be written and to describe the work, payment schedule, permit responsibility, and other agreed terms.
Read the scope. Then read the exclusions.
Who Pulls the Permit?
This should never be ambiguous.
CSLB states that a California home-improvement contract should specify who will obtain the necessary permits.
That person may be:
The licensed contractor.
The owner.
A permit consultant or designer acting within the appropriate arrangement.
Another authorized project participant depending on the jurisdiction and project.
Do not accept:
'Permits are included.'
Ask:
Who prepares the application?
Who prepares the drawings?
Who submits?
Who pays the fees?
Who responds to corrections?
Who coordinates revised factory documents if required?
Who schedules inspections?
Who handles final approval?
Those are different jobs.
Owner-Builder Is Not Just a Signature on the Permit
Sometimes an owner is told:
'Just pull the permit as owner-builder. We do this all the time.'
That deserves careful thought.
CSLB explains that when an owner signs the permit as an owner-builder, the owner assumes responsibility for the project, including permits, code compliance, inspections, ordering materials, paying suppliers, and supervising and paying subcontractors. Employment and workers' compensation obligations can also arise depending on how labor is used.
Owner-builder can be completely legitimate.
But it should be an informed choice.
Do not become the legal general contractor for your project simply because someone else does not want to be.
The Foundation Designer: The Person Who Makes the House Meet the Ground
The factory product and the foundation have to agree.
Someone must prepare the site-specific foundation design and coordinate:
Building loads.
Module or panel dimensions.
Anchor locations.
Hold-downs.
Utility penetrations.
Finished-floor elevations.
Site conditions.
Soils information where applicable.
Local structural requirements.
The manufacturer may provide foundation criteria.
A local engineer may design the actual foundation.
A prefab company may have an engineer who handles both.
Or the owner's contractor may coordinate it.
Ask:
Who is responsible if the factory drawings and foundation drawings do not match?
That is not a theoretical question.
The Site Contractor: Often Doing Work the Pretty Rendering Never Shows
On some projects, the general contractor handles the site.
On others, a separate excavation or site contractor does it.
That work may include:
Clearing.
Excavation.
Grading.
Building pad.
Utility trenching.
Driveway.
Drainage.
Retaining work.
Backfill.
Compaction.
Construction access.
Site restoration.
If the manufacturer says site work by owner, the owner needs to identify who will perform this work before treating the manufacturer's price as the project price.
The Installer or Set Crew: A Critical Handoff
Someone has to turn the delivered factory product into an installed building.
That may involve:
Receiving modules.
Rigging.
Setting units on the foundation.
Joining modules.
Structural connections.
Weatherproofing joints.
Roof completion.
Exterior finish completion.
Interior marriage-line work.
Utility connections between modules.
Touch-up and transportation repairs.
Ask whether the installer works for the manufacturer, dealer, or owner.
Then ask who warranties the installation.
A factory defect and an installation defect may be the responsibility of different companies.
The Crane Company: Responsible for the Lift, Not the Whole Project
The crane company generally needs accurate information about:
Module weights.
Pick distances.
Crane location.
Ground conditions.
Rigging.
Delivery sequence.
Site access.
But the crane operator is not necessarily responsible for determining whether your entire site is ready.
Someone needs to coordinate the crane company, transporter, installer, and foundation contractor.
If the crane arrives and cannot safely set up because the pad is not ready, the resulting standby or remobilization costs may land somewhere.
Know where before set day.
The Transporter: Responsible for Moving What Can Actually Be Moved
The transporter may handle:
Route planning.
Oversize permits.
Pilot cars.
Truck scheduling.
Delivery sequencing.
But who verifies the private road, driveway, gate, bridge, final turn, and building-pad access?
Do not assume the transportation company has accepted responsibility for every foot between the factory and the foundation unless the agreement says so.
Public-road delivery and final-site delivery are not always the same scope.
Utility Companies: They Control Their Part of the Schedule
Your contractor may coordinate utility work.
They do not control the utility company.
Electrical, water, gas, or other providers may have their own:
Applications.
Design requirements.
Fees.
Engineering.
Inspections.
Equipment.
Scheduling.
Lead times.
Determine who submits utility applications and when.
A fast factory schedule cannot compensate for a utility application that was started six months too late.
The Designer, Architect, Engineer, or Permit Consultant
Depending on the project, one or more professionals may be responsible for turning the building and parcel information into an approvable local submittal.
Possible tasks include:
Site plans.
Code analysis.
Foundation coordination.
Structural design.
Grading plans.
Energy documents.
Permit applications.
Agency coordination.
Plan-check responses.
Revision management.
Do not assume the manufacturer handles local corrections because it supplied the factory plans.
Do not assume the local designer can change the factory product without manufacturer or HCD-process implications.
Someone needs to own coordination between the two sets of documents.
The Owner: Responsible for More Than Writing Checks
Even with an excellent manufacturer and contractor, the owner has responsibilities.
At minimum, the owner should understand and approve:
The project scope.
The budget.
The contracts.
The product being purchased.
The property-development assumptions.
The payment schedule.
The major selections.
The schedule.
Changes to scope or price.
Who is responsible for each major task.
The owner may also be responsible for items specifically excluded from the other contracts.
That can include hiring separate consultants, paying agency fees, arranging financing, making selections, obtaining easements, or coordinating work specifically designated as owner responsibility.
The owner does not need to personally manage every detail.
But the owner needs to know who is managing it.
Responsibility for Corrections: Decide This Before Plan Check
Imagine the building department issues corrections involving:
The site plan.
Foundation.
Factory structural drawings.
Fire access.
Electrical service.
Energy compliance.
Drainage.
Who responds?
The answer may be different for every comment.
A good project team establishes this before corrections arrive.
For example:
Manufacturer/design approval team - factory design comments.
Local engineer - foundation or site structural comments.
Designer/permit consultant - site plan and general local corrections.
Civil engineer - grading/drainage comments.
Contractor - construction-method or field-condition information.
Owner - decisions, signatures, fees, or documents assigned to the owner.
Without coordination, correction notices get emailed around while the permit clock stops.
Responsibility for Inspections
HCD states that installation of California Factory-Built Housing is subject to local building-department inspection.
Local inspections may cover site-specific work such as foundation and installation, while the HCD insignia tells the local official that the factory-built portion was inspected and approved under its approved plans.
Someone needs to:
Request inspections.
Make sure the correct approved plans are onsite.
Provide access.
Coordinate subcontractors.
Respond to inspection corrections.
Schedule reinspection.
Track final sign-offs.
That is often the local contractor.
Do not assume it is.
Responsibility When Something Does Not Fit
This is where contracts become very important.
What happens if:
The foundation anchor locations do not match the module?
A module arrives with transportation damage?
The site dimensions differ from the drawings?
A utility penetration is in the wrong location?
The crane cannot make the planned pick?
The building department requires a field correction?
The factory component needs modification after installation?
HCD distinguishes between factory-stage and post-installation modifications: after installation, alterations to FBH are subject to local building-department approval.
That means field improvisation is not always as simple as cutting something and making it fit.
Determine who designs, approves, performs, and pays for corrective work.
Responsibility for Change Orders
With California home-improvement work, CSLB requires changes to the contract price or scope to be documented in a written change order signed before the changed work is performed.
Prefab projects can create change orders at several layers:
Factory changes.
Local contractor changes.
Foundation changes.
Site-condition changes.
Jurisdiction-required changes.
Owner-requested changes.
Ask each party what markup or fees apply.
More importantly, determine who has authority to approve additional cost.
Nobody should be able to create a $15,000 owner obligation through an undocumented conversation between two vendors.
Responsibility for Warranty Work
A completed prefab project can have several warranties.
Potentially:
Manufacturer warranty.
Appliance warranties.
Window or roofing manufacturer warranties.
Installer warranty.
General contractor workmanship warranty.
Subcontractor warranties.
If water enters at the connection between two modules, is that a factory issue or installation issue?
If a pipe installed at the factory leaks after the onsite connection, who responds?
If siding is damaged during transportation, who repairs it?
If the foundation settles, who evaluates it?
Ask for a warranty responsibility map before the project is finished.
'Covered by warranty' is not enough. Covered by whose warranty?
Responsibility for Paying Subcontractors and Suppliers
If you hire a licensed general contractor, understand how subcontractors and suppliers are being paid and use appropriate payment and lien-release practices.
If you act as owner-builder, CSLB warns that you take on responsibility for ordering materials, paying suppliers, and supervising and paying subcontractors.
Prefab adds another layer because the factory product itself may be purchased under a separate agreement.
Keep the payment streams clear:
Manufacturer.
Dealer.
General contractor.
Site subcontractors.
Consultants.
Utility providers.
Government fees.
Do not assume paying one company means everyone else has been paid.
Create a Responsibility Matrix Before You Sign
This is one of the simplest tools I recommend.
Make a spreadsheet with the project tasks in the left column and the project parties across the top.
Rows might include:
Zoning feasibility.
Site plan.
Survey.
Factory plans.
Foundation engineering.
Local permit submission.
Plan-check corrections.
Grading.
Foundation construction.
Septic/sewer.
Water.
Electrical service.
Fire access.
Delivery.
Crane.
Set/installation.
Utility hookups.
Local inspections.
Final corrections.
Final approval.
Warranty.
For every row, identify:
Who performs it.
Who coordinates it.
Who pays for it.
Whose contract includes it.
If a row is blank, you found a gap.
If two companies both claim the same row, you may have found an overlap.
Find both before construction.
A Simple Example
Imagine a modular ADU.
The responsibility map might look like this:
Manufacturer - factory plans, factory construction, HCD approval process, factory finishes, product warranty.
Local designer/permit consultant - site plan, local permit package, coordination of factory and site documents, plan-check responses.
Engineer - site-specific foundation design.
General contractor - excavation, foundation, site work, utility trenches, onsite completion, inspections.
Transporter - factory-to-site transportation.
Crane/set crew - lifting and placement.
Utility company - utility-side service work.
Owner - contracts, financing, fees, selections, approvals, and any specifically excluded scope.
That is only an example.
Your project may allocate responsibility completely differently.
The point is that every task has a name beside it.
When 'Turnkey' Really Can Be Turnkey
Some companies genuinely provide a very broad project scope.
That can be valuable.
A true broad-scope provider may coordinate:
Design.
Engineering.
Permitting.
Foundation.
Site work.
Manufacturing.
Transportation.
Crane.
Installation.
Utilities.
Inspections.
Final completion.
If so, great.
But verify it in the written scope.
Even a turnkey contract may exclude:
Government fees.
Utility-company charges.
Unforeseen rock.
Hazardous materials.
Major offsite improvements.
Special environmental studies.
Owner upgrades.
Unusual site conditions.
Turnkey should reduce the number of handoffs.
It should not eliminate your need to understand them.
When the Owner Is Effectively the Project Manager
At the other end of the spectrum, you may buy the factory unit directly and separately hire everyone else.
That can save money for an experienced owner.
It can also mean the owner is coordinating:
Manufacturer.
Engineer.
Building department.
Site contractor.
Foundation contractor.
Electrician.
Plumber.
Septic contractor.
Transporter.
Crane.
Installer.
Inspectors.
That is project management.
If you want to do it, price your time and understand your responsibilities.
If you do not want to do it, hire someone whose contract clearly includes coordination.
Questions to Ask the Manufacturer
What exactly are you responsible for?
Where does your scope end?
Who handles local permits?
Who designs the foundation?
Who coordinates your drawings with the foundation drawings?
Who transports the unit?
Who hires the crane?
Who installs it?
Who completes onsite finish work?
Who responds to factory-plan corrections?
Who handles factory defects?
Who handles transportation damage?
Who handles warranty service in my area?
Which items are explicitly the owner's responsibility?
Questions to Ask the Contractor
Which portions of the site work are included?
Is the foundation included?
Are utility connections included?
Are utility-company charges included?
Who coordinates delivery and crane work?
Who is responsible for making the site ready for delivery?
Who requests inspections?
Who responds to field corrections?
Does your contract include final completion after the modules are set?
What work is excluded?
Who handles warranty issues involving installation?
What do you expect the manufacturer or owner to provide before you begin?
Questions the Owner Should Be Able to Answer
Who owns the permit process?
Who owns foundation coordination?
Who owns the delivery plan?
Who owns the crane/set plan?
Who owns utilities?
Who owns site work?
Who owns inspections?
Who owns corrections?
Who owns warranty coordination?
Who is the single person I call when two parties disagree?
That last question matters.
Complex projects benefit enormously from one person who understands the whole project rather than only one contract.
Common Responsibility Traps
'The manufacturer said the contractor handles it.' Did the contractor's written scope say that?
'The contractor said the factory provides the plans.' Factory plans may not be the complete local permit package.
'Permit assistance is included.' Who actually prepares, submits, corrects, and closes the permit?
'Foundation by others.' Who are the others?
'Site work by owner.' That means you need to hire and coordinate it unless another contract says otherwise.
'Delivery included.' To where?
'Installation included.' Does that include crane, module connections, roof completion, utilities, finish repairs, and inspection corrections?
'Turnkey.' List the keys.
'Warranty included.' Which company handles which failure?
'We'll figure it out in the field.' Some things can be. Responsibility should not be one of them.
The Bottom Line
A prefab project is not one transaction.
It is a chain of responsibilities connecting a factory-built product to a specific piece of land.
The manufacturer owns the factory work it contracted to provide.
The contractor owns the construction scope it contracted to perform.
Designers and engineers own their professional scope.
Transporters and crane companies own their defined services.
Local agencies regulate and inspect the portions under their jurisdiction.
And the owner owns whatever remains unassigned - intentionally or accidentally.
Your job before signing contracts is to make sure 'accidentally' is as close to zero as possible.
Put every major project task in writing.
Assign it to someone.
Confirm who coordinates it.
Confirm who pays for it.
Then make sure the contracts agree.
That is how a collection of vendors becomes a project team.
Looking Ahead
Next: Prefab Red Flags: What Should Make You Walk Away?
We will look at the sales claims, contract language, deposit demands, approval promises, pricing tricks, missing documentation, and company behavior that should make a buyer slow down - or leave entirely.
If you are coordinating a California prefab, modular, manufactured, panelized, tiny-home, ADU, or SFR project, Buchanan Land Use Consulting can help identify the permitting responsibilities and project gaps before they become expensive construction problems.
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