Contractor Change Orders: How They Work and How to Handle Them
A change order is a written amendment to a construction contract that has already been signed. It records a change in the work and what that change does to the price and the schedule. Both sides sign it before the extra work starts. If you are a homeowner, property manager or general contractor, that one habit does most of the work of keeping a project on budget.
This guide covers what a change order contains, how it differs from an addendum or a directive, what California requires, and how to handle changes on flooring, tile and bathroom jobs.
TL;DR
A change order is a signed, written amendment to an existing contract. It adjusts scope, cost, time, or all three.
Never start extra work on a verbal “while you’re at it.” Get the price and the schedule impact in writing first.
In California, changes to a home improvement contract must be in writing, and the state’s contractor board tells homeowners to have both parties sign them.
The costliest change orders usually come from vague scope at the start, not from real surprises on site.
A good change order names the work, the exact dollar amount added or removed, and the effect on the completion date.
Table of Contents
What a contractor change order is
According to AIA Contract Documents, a change order is a written agreement that records a change in the work and any adjustment to the contract sum or contract time. Because the necessary parties negotiate and sign it, it carries the same weight as the original contract. On a private residential job, those parties are usually the owner and the contractor. On larger commercial work, the architect often signs too.
Two points matter in practice:
It only exists after signing. Changes you negotiate during bidding are just a revised bid. A change order amends a contract that is already in force.
It needs agreement. Neither side can impose one. If the contractor proposes it and the owner declines, the original contract stands.
In the field, people use “change order” loosely for anything that alters the job. Precision helps. A conversation at the job site is not a change order. A text that says “sure, go ahead” is a weak substitute. The document is the signed page that states the new scope, the new number and the new date.
What goes in a change order
Whether you use a template, a software form or a one-page sheet, a usable change order carries the same elements:
The project and original contract. Address, contract date, and the original contract amount.
A description of the change. Specific enough that a stranger could tell what was added or removed. “Extra tile work in bath” is vague. “Remove and replace 18 sq. ft. of subfloor under the shower pan, then install the same porcelain tile as the main field” is a scope.
The price effect. The exact amount added or deducted. Washington State’s auditor, in its change order best practices, recommends detailed written proposals that itemize labor, materials, equipment and markup. The guidance is written for public agencies, but the discipline applies to a bathroom as much as to a school.
The schedule effect. Added days, or a statement of no change. Owners forget this line and contractors skip it, then both argue about it at the end.
Payment terms. When the extra amount is due: with the next progress payment, on completion, or up front for special-order materials.
Signatures and dates. Both parties, before work begins.
A simple example. A homeowner signs a contract to retile a bathroom floor. When the old tile comes up, the crew finds a section of soft subfloor. The contractor documents it, writes a change order for the repair with a price and one extra day, and the owner signs. Work continues. At the final invoice, nobody is surprised.
Change order vs. addendum vs. directive
These terms get mixed up. In the plainest sense:
Document | What it does | When it is used |
Change order | Amends the signed contract with agreed scope, price and time | After signing, when both sides agree |
Addendum | Adds or clarifies terms, often before signing or as a supplement to the contract | Usually during bidding or contract formation |
Change directive | Owner instructs the change to proceed before cost or time is agreed | When work cannot wait for a negotiated price |
The distinction between a change order and a directive comes from the AIA material cited above: a directive is an owner’s order issued before agreement on cost or time is reached, and once the contractor signs it, it becomes a change order. If the contractor disagrees, dispute resolution procedures apply. Addendum is a looser word. Some contracts use it for what others call a change order, so read what your own contract calls a post-signing amendment and follow that procedure.
On commercial projects you will also see acronyms. The Autodesk Build documentation lists the common ones: a PCO (potential change order) is the early stage where cost is estimated, a COR (change order request) formalizes it for review, and an OCO (owner change order) or SCO (subcontractor change order) is the final executed document. SCO is the answer if you wondered what the letters mean: it modifies the subcontract between a prime contractor and a subcontractor, and either party may initiate it.
What California requires
Our work is in California, so here is what the state’s rules say. Check the current text or ask a licensed professional about your specific contract.
The Contractors State License Board (CSLB) states that a written contract is required for home improvement projects over $500, and that the contract and any changes to it must be in writing and easy to understand. Its consumer pamphlet, What You Should Know Before Hiring a Contractor, says all changes to the contract, or change orders, need to be in writing and signed by both parties.
The statute behind this is Business and Professions Code section 7159, which lists what a home improvement contract must contain. It includes a requirement that the contract carry a disclaimer on change orders, so a compliant California contract should already explain how changes are handled. If your contract does not mention change orders at all, ask the contractor to add the procedure before you sign.
Two practical consequences:
Homeowners can reasonably refuse to pay for extras that were never put in writing and signed. Do not rely on that as a plan. Disputes cost time even when you are right.
Contractors who do extra work on a handshake risk not being paid for it, and risk trouble with their license. A written change order protects both sides equally.
The same pamphlet also notes that the homeowner’s three-day right to cancel (five days if 65 or older) can be waived in certain service and repair contracts. That is a separate rule from change orders, but a reminder that the paperwork you sign carries real consequences. If you have a question about your rights on a specific contract, the CSLB is the body to call, and a construction attorney is the person to see for a dispute.
Why change orders happen
There are three honest reasons, and they cost very different amounts.
1. The owner changes their mind. A different tile, a niche in the shower wall, a bigger hearth. These are legitimate, and the owner controls the cost by deciding early.
2. Hidden conditions. Rot under a vanity, an uneven slab, cracks that were covered by old flooring, moisture trapped beneath a surface. No contractor can see these before demolition or surface prep. A good contract anticipates them with a clear process for pricing them when found.
3. Unclear scope. The contract was vague, so the two sides assumed different things. This is the expensive one. A thesis from the University of Texas at Arlington on rework indicators across 44 construction projects points to design problems, vague scope and poor communication as the main drivers of rework, and found that clear communication and experienced personnel reduce the need for change orders.
The scale of the problem is documented, though in a different setting. Researchers studying change orders on highway projects call them one of the main challenges the construction industry faces. Public infrastructure is not your bathroom, but the lesson carries over: the earlier a change is identified and formalized, the less it disrupts everything after it.
Change orders on flooring, tile and bathroom jobs
Residential finish work has its own predictable change triggers. Knowing them lets you ask the right questions before signing.
Subfloor and substrate surprises
Tile, epoxy and refinished hardwood are only as good as what lies beneath. Soft plywood, deflection, old adhesive, moisture and cracked or uneven concrete all show up once the old surface is removed. Floor leveling and crack repair are common line items for exactly this reason. Ask your contractor up front: what is included if the subfloor needs work, and how will it be priced? A fair contract names a unit price or a process, so the change order is a formality instead of a negotiation.
Material changes
Swapping tile, changing a finish color or upgrading a coating system after ordering may mean restocking fees, lead times or a second trip. Put the selection deadline in the contract and treat any change after that as a change order.
Added rooms and “while you’re here” requests
The most common request on a flooring job is more flooring. It is also the easiest to handle: a short change order with a square-footage price, signed before the crew moves on. Bundling work can also lower the cost of mobilization, which is worth asking about. Our post on bathroom remodel ROI explains how scope decisions affect what a project returns, and it is a good read before you decide to expand one.
Accessibility and code items
Widening a doorway, adding blocking for grab bars or changing a threshold can appear mid-project once someone points out the need. Planning these at the start avoids rework; see our guide to an accessible bathroom remodel. The same goes for converting a tub to a shower, where plumbing and code questions are best resolved before demolition (tub to shower conversion costs and codes).
Water damage
If water has already hit a hardwood floor, the scope of repair can change fast as moisture readings come in. Our 24 to 48 hour triage guide for water damaged hardwood explains why early decisions matter, and why the original estimate may need a documented update.
How to run the change order process
Whether you are the owner, the property manager or the contractor, the sequence is the same.
Stop and describe the change. The person who spots the issue says so in writing, with a photo if it helps.
Price it. The contractor issues a written proposal with labor, materials and any markup broken out, plus the days it adds.
Review. The owner asks questions, compares with the original scope and decides. Saying no is a valid outcome.
Sign before starting. The signed change order is attached to the original contract. Keep a copy on both sides.
Track the running total. Keep a simple log of original price, each change and the revised total. It prevents the shock at the end.
Close out. Final payment matches the original contract plus the signed changes, and nothing else.
The Washington State guidance referenced earlier makes a point worth borrowing for any size of job: the contract’s “changes in the work” clause should require signed authorization before out-of-scope work begins. If your contract lacks that clause, add one.
For property managers and contractors
If you manage multiple units or hire subcontractors, standardize the paperwork. One form, one approval path, one place where signed copies live. It is also worth reading how others handle change in complex environments. This overview of workplace change management for tenants is Australian and commercial-office focused, so the rules it mentions are not US law, but its focus on protecting budgets during fit-out changes applies to any property manager who has watched a small change grow.
If you are a prime contractor engaging a flooring subcontractor, the SCO is your instrument: it modifies the subcontract and should flow from the owner’s change order so that scope and money match up the chain.
Red flags in a change order
No schedule line. Cost without time is half a document.
A lump sum with no detail. Ask for labor and materials separately.
Pressure to sign today. Legitimate hidden-condition changes can be photographed and explained.
Work already underway. If the crew has already done the work, you are being asked to approve, not to decide. Ask the contractor to stop and put it in writing.
Changes that fix the contractor’s own omissions. If the original scope clearly included something, it is not an extra.
Vague words. “Misc.,” “as needed” and “allowance” without an amount invite disputes.
For reassurance: a contractor who writes up changes promptly is usually the one you want. It means they are tracking costs and are not planning to bury them in a final bill.
Our perspective
We build our jobs around epoxy coatings, tile, hardwood refinishing, shower builds and bathroom remodels, and we have learned where the money moves on those projects. It almost always moves at the surface: what is under the old floor, how flat the slab is, which finish the owner finally chooses.
So we try to answer those questions before a contract is signed. A clear, itemized estimate and a real consultation up front mean fewer changes later, and the changes that do come are explained and priced in writing before the work starts. Transparency is how we describe our approach, and a change order is the clearest place to show it.
Our advice to any owner is simple. If a contractor says something will “just be a little extra,” ask what the number is and ask for it on paper. If we are the contractor, we would rather pause for ten minutes to write it down than spend weeks sorting out a misunderstanding.
— Jacob
Planning a flooring or bathroom project?
If you are comparing proposals for epoxy coatings, tile, hardwood refinishing or a bathroom remodel, we will walk you through the scope, explain what could change and put the process in writing. See our full list of services or look at our flooring systems and tile installation pages. If you are weighing refinishing, our hardwood refinishing cost guide shows how method affects price.
FAQ
Does a change order have to be in writing?
In California, yes for home improvement work. The state licensing board says changes to the contract must be in writing and signed by both parties. Even where the law is less strict, a written and signed change order is the only reliable proof of what was agreed.
Can a contractor charge for extra work without a change order?
It is risky for the contractor and a reason for dispute with the owner. Under California’s rules, changes belong in a signed writing, so extra charges that were never documented are open to challenge. If you receive a bill for something you did not approve in writing, ask for the documentation and contact the CSLB or a construction attorney for your situation.
What is the difference between a change order and an addendum?
A change order amends a contract that has already been signed and records the agreed change in scope, price and time. An addendum is a broader term, often used for terms added or clarified around contract formation. Check what your contract calls each one and follow its procedure.
Who pays for a change order?
The change order says. If the owner requested the change, the owner usually pays. If the change is a correction of the contractor’s own error or omission from the original scope, it should not be billed as an extra. Hidden conditions are the gray area, which is why a good contract explains how they will be priced.
What does SCO mean in construction?
SCO stands for subcontractor change order. It modifies an existing subcontract when scope, schedule or cost changes between a prime contractor and a subcontractor.
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