Change Orders: How to Stop Them Before They Start
A change order is a written modification to the original contract, usually increasing the price and extending the schedule. On a typical renovation, change orders add 10–20% to the total cost. On poorly-scoped projects, 30–50%. The math of preventing change orders — spending more time on scope and less time on surprises — is one of the highest-ROI decisions a homeowner can make.
What a change order really costs you
The 10–20% rule on typical projects
Budget 10–20% of the contract price for change orders on a well-scoped renovation. That’s the baseline you should expect even when everyone is doing their job. Zero-change-order projects exist, but they’re rare and usually mean someone gave something up to get there.
Why poorly-scoped projects hit 30–50%
On poorly-scoped projects, change orders can consume 30–50% of the total. That’s the difference between a $200,000 project and a $290,000 project — and it’s almost always foreseeable in the bid documents.
The hidden costs beyond the change-order price
The dollar amount on a change order understates the real cost. Change orders also buy you: schedule delay (additional weeks of living in a job site or a rental), decision fatigue (every change requires design and pricing choices under pressure), and the wear on the homeowner-contractor relationship, which is one of the most underrated drivers of a painful project. Every change order you don’t have to process is a week you don’t lose to it.
The four sources of change orders
Homeowner-requested changes
Scope additions or alterations you decide on after construction starts. The mid-project “while we’re at it” decisions.
Unforeseen conditions
Rot, hidden structural damage, outdated electrical, surprises behind walls. The things nobody knew were there until the drywall came off.
Scope ambiguity
Work that could reasonably be interpreted in multiple ways based on the contract documents, and that gets resolved in the contractor’s favor through a change order.
Design changes from the architect
Drawing revisions after construction starts, typically because the drawings were incomplete at permit or because code or constructability issues surface in the field.
Homeowner-requested changes (the most avoidable)
Decide before construction starts
This is the most avoidable category. Make every major design and scope decision before construction begins. Paint colors you can still defer; the location of the kitchen island, the height of the vanity, and whether to move a window you can’t.
Why mid-project changes cost 2–3x
Every scope change during construction runs 2–3x the cost of the same change in planning. The math is simple: work already completed often has to be undone and redone, crews get pulled off schedule, ordered materials may need to be returned or reordered, and inspections that were scheduled get rescheduled. A $2,000 scope decision in design becomes a $5,000–$6,000 change order in week six.
How to handle design impulses during demo
Demo is when homeowners see the bones of the house for the first time and get ideas. Some of those ideas are legitimately good; most are recency bias. Set a rule for yourself: write down every mid-project impulse, but don’t act on any of it for 48 hours. That alone kills most of the expensive impulses before they become change orders.
Unforeseen conditions (mostly unavoidable, but minimizable)
What “unforeseen” actually means
Unforeseen conditions are, by definition, things that couldn’t reasonably have been known before work started. The honest version of this category is small — maybe 5% of the project on a typical older home. The dishonest version is large, when things that were knowable get re-classified as surprises.
Invasive investigation during design
Minimize unforeseens by doing invasive investigation before construction. Selective demo during design, infrared imaging, scope inspection of mechanical systems. Peek behind the walls before you sign the construction contract, not after.
The $2,000 that saves $20,000
The $2,000 you spend investigating during design saves $20,000 in surprises during construction. The ratio sometimes goes higher — a plumbing inspection that reveals a failing cast-iron stack on a 1920s home lets you scope the stack replacement into the original contract rather than discovering it mid-project at change-order pricing.
Common surprises in older homes by era
Pre-1950 homes: knob-and-tube wiring, lead paint, lead water service lines, galvanized supply lines, plaster-and-lath walls hiding framing that doesn’t meet modern spec. 1950s–1970s homes: aluminum wiring in certain years, undersized electrical service, asbestos in old insulation or tile mastic, cast-iron drain stacks nearing end of life. 1970s–1990s homes: polybutylene plumbing, FPE or Zinsco panels, undersized HVAC for current expectations. Knowing your era tells you what to look for during invasive investigation.
Scope ambiguity (the biggest opportunity)
A tight scope leaves nothing to interpret
Scope ambiguity is the biggest single category, and the most preventable. A tight scope leaves nothing to interpret. If both the homeowner and contractor can read the same line and come away with the same understanding of what’s included, you’ve written it well.
The 12 scope items contractors leave vague
See our separate post on the 12 scope items contractors leave vague — demolition and debris removal, permits and permit fees, structural adjustments that reveal themselves mid-project, electrical panel work, flooring transitions, HVAC modifications, paint scope for adjacent rooms, tile underlayment and prep, appliance hookups, final cleaning, punch list, and warranty period. Each one is an opportunity for a change order if left unspecified.
How to read your scope for gaps
Read the scope with the contractor’s incentive in mind. For every line, ask: what’s NOT included here that a reasonable person might assume is? “Install new vanity” — does that include plumbing supply/waste adjustments, counter connection, backsplash, caulking, disposal of old vanity? A good scope answers all of those explicitly. A bad scope lets the contractor interpret them out.
Design changes at the architect level
Incomplete drawings at permit
If the architect’s plans are incomplete at permit, expect field changes. Incomplete drawings defer decisions to the job site, where they get made under time pressure with incomplete coordination between trades.
Getting complete drawings before bidding
Resist by getting complete drawings before bidding, not after. Bidding on 60%-complete drawings invites change orders because every gap in the drawings is priced as the contractor’s best guess — and often as a placeholder that gets revised upward in the field.
What “complete” actually looks like
A complete drawing set for a typical residential renovation includes: floor plans with dimensions and opening specifications, reflected ceiling plans, interior elevations of every wall with cabinetry or trim, electrical plans with fixture and switch locations, plumbing diagrams, structural drawings where needed, and a comprehensive specification section. Photos of “what we want” and a general floor plan is not a complete drawing set, no matter what your architect may tell you.
How to handle the change orders you can’t avoid
Require written change orders before work proceeds
No written change order, no work. This should be in your contract and enforced without exception. Verbal authorizations become “you told me to” disputes later.
Get pricing before authorizing
Require pricing in writing before you approve the scope change. Contractors do not “figure out cost later.” They figure it out now, give you a number, and you decide.
Understand markup
Change orders carry markup. Know what your contractor’s markup structure is going in (it should be in the contract), and verify it’s applied consistently when change orders come through.
Keep a running total
Keep a running total of approved change orders so you know where you stand against contingency at any point in the project. A spreadsheet with date, description, amount, cumulative total, and remaining contingency is enough.
Never authorize verbally
Don’t approve verbally. Don’t approve by text. Sign the change order before the work proceeds. It’s the single most common way homeowners end up surprised by the final invoice.
Contingency math
New-ish homes: 10–15%
Plan 10–15% contingency on homes built in the last 20–30 years. Modern construction, known materials, limited surprises.
1960s–1970s homes: 15–20%
Mid-century construction quality varies widely. Some is excellent; some hides aluminum wiring or asbestos issues. Budget accordingly.
Pre-1950 homes: 20–30%
Pre-1950 homes almost always surprise you somewhere. Old framing, mystery wiring, plaster-and-lath, outdated plumbing systems. 20–30% contingency is appropriate, and on historic homes the top end can go higher.
Contingency is not budget
Treat contingency as separate from the project budget. If you spend $300K on a $400K budget ($100K in contingency), do not spend the contingency on upgrades just because it’s there. Hold it back for real surprises. Treating contingency as discretionary money is how a $500K contract turns into a $650K project when the last surprise hits and there’s nothing left to absorb it.
What to do with unused contingency
If you finish the project with contingency left over, congratulations — you scoped well and were lucky with unforeseens. Use it for deferred upgrades (better appliances, the deck off the back you wanted, landscaping), or put it back in savings. What you should not do is announce the unused contingency to the contractor in week 10; it tends to mysteriously find a home.
Tools that reduce change orders
ScopeWut for tight scope
ScopeWut builds a scope that covers the 12 most-common ambiguous areas and forces the homeowner and contractor to agree on them in writing before work starts.
CostWut for allowance calibration
CostWut benchmarks realistic pricing so allowances in your contract are appropriate — and allowance overruns (when the tile you pick costs more than the allowance assumed) stop being surprises.
PermitWut for code-driven surprises
PermitWut flags code issues that surface mid-project — egress window requirements in basement finishes, updated outlet or GFCI rules in kitchen remodels, upgraded panel requirements when adding new circuits. Together these reduce change-order frequency meaningfully.
Frequently Asked Questions
How much markup do contractors charge on change orders?
10–25% is standard. Higher markup on small change orders is common because overhead doesn’t scale down.
Can I refuse a change order?
You can decline the scope change if it’s homeowner-requested. For unforeseen conditions, you typically need to address the issue somehow — decline means the project stops.
What if my contractor does work without a change order?
Document it in writing. Unauthorized work generally isn’t billable without your approval. Get this requirement in writing in your contract from day one.
How do I price a change order fairly?
A fair change order has the same line-item structure as the original bid: labor hours at a stated rate, materials at a stated markup, and overhead/profit applied per the contract terms. If you’re getting a single number with no breakdown, ask for the breakdown. Any contractor unwilling to show you the math on a change order is telling you something about the rest of the project.
What if the contractor insists on proceeding before I sign?
Say no. The only exception is genuine emergency — an active water leak, an exposed electrical hazard — and even then, get the scope and approximate cost in writing by text or email before work starts. “We had to do it, here’s the bill” is not a conversation you want to have.
Is there a legal limit on change-order markup?
Not typically. Markup is governed by your contract, not statute. That’s why getting markup percentages explicitly stated in the original contract matters so much — it’s your only protection against escalating markup on change orders.
