How to Read a Contractor or Prefab Bid Without Getting Burned

Why the Lowest Number Is Often Not the Lowest Price

You have the property. You have a plan. You have found a licensed contractor, modular company, prefab builder, or tiny-home manufacturer that looks promising.

Then the bids arrive.

One says $165,000. Another says $212,000. A prefab company advertises the house itself for $119,000.

At first glance, this looks like a price comparison. Usually it is not.

The most important question is not: What is the bid? It is: What exactly does that number buy me?

Two companies can appear to be bidding the same ADU or house while actually pricing completely different scopes of work. With prefab, modular, and tiny-home projects, the gap between the advertised unit price and the completed project price can be enormous.

Start With Scope, Not Price

Before comparing numbers, compare scope. A useful bid should make it possible to understand what the contractor or company is actually providing.

Look for plans and engineering, permitting, surveying, site preparation, grading, foundation, the building or structural shell, roofing and exterior finishes, windows and doors, interior finishes, plumbing, electrical, HVAC, appliances, utility connections, sewer or septic, water, fire-access work, transportation, crane or setting costs, assembly, cleanup, and final inspections.

If one bid includes all of those and another includes only the structure, they are not competing bids.

Normalize the scope before you compare the price.

The Word 'Turnkey' Does Not Tell You Enough

Prefab and modular companies love the word turnkey. Ask what it means.

Does turnkey include the foundation? Site excavation? Utility trenching? Sewer or septic? Water connection? Electrical service upgrade? Transportation? Crane? Module setting? Exterior site completion? Decks and stairs? Driveway work? Fire requirements? Permits and local fees? Title 24 or site-specific engineering? Final inspection?

A company can legitimately call its portion turnkey while leaving the owner responsible for a large amount of site work. The word itself has no value unless the scope behind it is clear.

Prefab Price vs. Project Price

The price of a factory-built, modular, panelized, or tiny-home product is not necessarily the price of a completed legal dwelling on your property.

California factory-built housing may be inspected and approved during factory production, but installation remains subject to local building-department inspection. Your project may still require local planning and building permits, site plans, foundation engineering, grading and drainage, utilities, sewer or septic, water, electrical service, fire access, transportation, crane or setting, on-site assembly, and local inspections.

So when you see a beautiful $99,000 or $149,000 prefab home online, do not ask only whether you can afford the home.

Ask what it will cost to make that product a completed, permitted dwelling on your specific parcel.

Find the Exclusions Before They Find You

I often learn more from the exclusions than the total.

Look for phrases such as by owner, by others, not included, allowance only, TBD, subject to field conditions, permit fees excluded, utility fees excluded, engineering excluded, and site work excluded.

Some costs genuinely cannot be known until the site is evaluated. But every exclusion represents either a cost you must pay somewhere else or a risk you are accepting. Create an exclusion list and put an estimated number next to every item you can.

Allowances Are Not Fixed Prices

An allowance is money included for an item that has not been finally selected or priced. Examples might be a $3,000 appliance allowance, $4-per-square-foot flooring allowance, or $8,000 cabinet allowance.

Allowances can be reasonable, but they can also make a bid look artificially low. If you know you want $18,000 worth of cabinets and the bid carries an $8,000 allowance, the project is already effectively $10,000 over the apparent price.

Ask whether labor, sales tax and delivery are included, what quality the allowance realistically buys, what happens if the actual cost is lower, and what markup applies if it is higher.

An unrealistic allowance is simply a future change order wearing nicer clothes.

Look for Missing Site Work

Site work is one of the easiest places for a project budget to explode. A building price may not include clearing, demolition, excavation, exporting soil, imported fill, rock excavation, grading, retaining walls, drainage, driveways, construction access, erosion control, tree removal, or utility trenching.

On a flat suburban lot some of those may be minor. On a rural or sloped property they can be enormous.

Do not let a detailed building quote distract you from an almost blank site-work section.

Utilities Need Their Own Budget

Ask who gets the new dwelling connected to the world.

For electrical, determine whether the existing service is adequate, whether a service upgrade is included, who coordinates with the utility, and whether trenching, meters and panels are included.

For water, determine whether the connection or meter is included and, on rural property, whether well work or storage is required.

For wastewater, determine whether the sewer lateral and connection fees are included or whether septic work is required.

A bid that says plumbing included may mean plumbing inside the house. It does not necessarily mean the house will be connected to functioning water and wastewater systems.

Foundation: Included Means What?

Prefab buyers should be especially careful here.

Ask whether foundation engineering is included and site-specific, who excavates, who forms and pours, whether reinforcing and connections are included, who coordinates the foundation with the factory drawings, and what happens if field dimensions do not match the manufactured unit.

Factory approval and local site approval are different parts of the process. The interface between the factory product and the site work matters.

Transportation and Crane Costs Can Be Real Money

Ask how many loads are required, whether transportation is included, whether there is a mileage limit, who handles oversized-load requirements, who evaluates the delivery route, whether trucks can physically reach the site, whether crane service is included, how many crane hours are assumed, and who pays for delays.

A modular unit that cannot get around the last corner of a rural road is not a minor inconvenience.

Delivery feasibility belongs in the budget before the unit is ordered.

Permitting: Find Out Exactly Who Does What

Do not accept we help with permits as a complete answer.

Ask who prepares the site plan, foundation plans, site-specific structural engineering and energy documentation; who submits to the jurisdiction; who responds to corrections; who coordinates factory plans with local plans; who pays permit and impact fees; and who handles inspections and final approval.

For California home-improvement contracts, the written agreement should identify who obtains necessary permits. Prefab projects often involve both factory-approved documents and local site-specific approvals, so the responsibility line needs to be especially clear.

Permit ready is not the same thing as permitted.

Do Not Pay Twice - Or Leave a Gap

Complex projects can involve a manufacturer, dealer, designer, engineer, licensed contractor, site contractor, installer, and subcontractors.

You may discover that two parties both priced foundation coordination, electrical connection, crane coordination, engineering, permit support, or finish work. Or worse, each assumes the other included it.

Create a responsibility matrix. List every major scope item and identify exactly one party responsible for it.

Gaps cost money. Overlaps cost money too.

The Bid Should Match the Plans

Confirm the plan date and revision used for the bid.

If the bid was based on preliminary drawings and you now have approved construction documents, ask for it to be updated.

Look for assumptions such as standard foundation, no retaining walls, flat lot, normal soil, adequate existing electrical, sewer available at the property line, no rock, no hazardous materials, and easy site access.

A detailed price based on the wrong project is still the wrong price.

Beware of the Suspiciously Low Bid

Sometimes the lowest bidder is simply more efficient. Sometimes they have lower overhead or found a better construction approach.

And sometimes they missed half the job.

If several credible bids cluster around one number and one is dramatically lower, ask that bidder to walk through the scope line by line. Give them the opportunity to show you why they are cheaper.

If the explanation is vague, the difference may come back later through change orders, downgraded materials, schedule problems, or unfinished scope.

Change Orders: Know the Rules Before Construction

For California home-improvement contracts, changes to price or scope generally need to be documented in a written change order before the changed work begins.

Before signing, ask what markup applies to change orders, whether overhead and profit are added, whether there is a minimum fee, how credits are handled, what documentation supports unforeseen conditions, and who has authority to approve a change.

Change orders are part of construction.

Undefined change-order rules are optional chaos.

Payment Schedule: Do Not Let the Money Get Ahead of the Project

For California home-improvement work, the down payment generally cannot exceed $1,000 or 10 percent of the contract price, whichever is less. Progress payments should track the value of work performed or materials delivered.

The contractor should not be substantially ahead of you financially.

Factory or prefab purchase agreements may have a different payment structure because you may be buying a manufactured product under a separate agreement. That makes it especially important to ask who receives each payment, what has actually been produced at that stage, when title transfers, whether deposits are refundable, and what happens if the manufacturer fails, the permit is denied, or the unit cannot be delivered.

Do not assume contractor-payment protections answer every risk in a separate factory purchase agreement.

Compare Bids With a Spreadsheet, Not Your Memory

Create columns for each bidder and rows for the major scope items: base building, plans, engineering, permits, foundation, grading, transportation, crane, assembly, electrical, water, sewer or septic, HVAC, finishes, appliances, site work, fire requirements, access, cleanup, allowances, exclusions, and contingency.

Then calculate an estimated completed-project cost for each option.

That number is far more useful than the advertised base price.

Build a Contingency

Even a good bid cannot predict everything. Existing construction hides surprises. Soil can surprise you. Utility companies can require upgrades. Inspectors can identify field conditions. Owners change their minds.

A project budget with zero contingency is not a precise budget. It is an optimistic budget.

The appropriate contingency depends on the project and how many unknowns remain, but financial room for uncertainty should exist before construction begins.

Questions I Would Ask a Prefab Company Before Paying a Deposit

What exactly am I buying? Is it factory-built housing, manufactured housing, panelized construction, a tiny home on wheels, or something else? Is it approvable as the permanent SFR or ADU I intend to build? Which plans and California approvals are included? What still requires local approval? Is foundation design included? Site work? Transportation? Crane/set? Who assembles and finishes it onsite? Who connects utilities? Who handles local corrections? What happens if the jurisdiction requires design changes or the product cannot be delivered? What is excluded from the advertised price? What happens to my money if the project cannot proceed? Who handles warranty work after installation?

Questions I Would Ask a Licensed Contractor Before Signing

Which plan set did you bid? Can you give me a written scope? What is specifically excluded? Which items are allowances? Who obtains permits? Are permit fees included? Is site work included? Are utility connections included? What assumptions did you make about soil and access? Who are the major subcontractors? What is your change-order markup? How are credits handled? What milestone triggers each payment? Will you provide lien releases?

And one of my favorite questions:

What is not in this bid that you expect I will probably need?

A good contractor often knows exactly where owners underestimate the project.

Common Bid Traps

Turnkey: $149,000. Define turnkey.

Foundation included. Which engineering, excavation and site conditions are included?

Plumbing included. Inside the structure, or all the way to functioning sewer/septic and water?

Permit assistance included. Assistance is not necessarily preparation, submission, correction response or permit issuance.

Site work by owner. That may represent tens of thousands of dollars.

Allowance. Treat it as a placeholder, not a guaranteed finished price.

Starting at $99,000. Starting is doing a lot of work in that sentence.

We can figure that out after you sign. Sometimes true - but identify the financial risk before you sign.

The Bottom Line

A bid is not just a number. It is a description of who is responsible for what.

Read the scope. Read the exclusions. Challenge the allowances. Identify site work. Follow the utilities. Understand foundation responsibility. Price transportation and crane work. Clarify permitting. Make sure the bid matches the current plans. Understand change orders. Keep construction payments tied to progress.

And when prefab is involved, separate the price of the product from the cost of creating a completed legal dwelling on your parcel.

The cheapest bid is not the bid with the smallest number. It is the option that delivers the project you actually need at the lowest realistic completed cost and acceptable level of risk.

Looking Ahead

Next: Site Work: The Costs Nobody Includes in the Pretty Prefab Price.

We will break down grading, foundations, utility trenching, sewer and septic, wells, electrical upgrades, fire access, driveways, drainage, retaining walls, cranes, and the other work that can turn an inexpensive building into a very different project budget.

If you are comparing contractor, modular, prefab, or tiny-home proposals for a California property, Buchanan Land Use Consulting can help identify the permitting and site-development scope so you can compare proposals based on the whole project rather than the advertised building price.

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