Contracts for Construction: A 2026 Complete Guide

What Contracts for Construction Actually Do (and Why Most People Choose the Wrong Type)

A construction contract is a legally binding agreement that defines the scope of work, the price, how payment flows, who absorbs cost overruns, and how disputes are resolved. The contract type you sign is not administrative paperwork — it is the primary financial risk allocation decision of the entire project, made before a single shovel breaks ground.

Key takeaways

• Construction projects average 28% cost overruns; poor contract planning and change-order mismanagement account for roughly 70% of those overruns.
• The five main contract structures — lump-sum, cost-plus with GMP, cost-plus without GMP, unit price, and time-and-materials — each transfer cost risk to a different party.
• Signing a lump-sum contract before drawings are 90% complete routinely converts a "fixed price" into an uncontrolled cost-plus project through uncontested change orders.
• California (Cal. Civ. Code § 8811) and New York (N.Y. Gen. Bus. Law § 757) both capped retainage at 5% in late 2025/early 2026 — contracts using higher rates are now void in those states.
• AIA Document A201-2017 is the industry-standard set of general conditions; it must be coordinated with A101-2017 (lump sum) or A102-2017 (cost-plus with GMP) to form a complete contract.

Which Contract Type Should You Use? (A Decision Table)

Every article on construction contracts lists the contract types. Almost none explain how to choose. The decision is not about preference — it is about matching the level of cost-risk you can accept to the level of scope clarity you actually have at bid time.

Project Condition	Recommended Contract	Standard Form	Who Bears Overrun Risk
Drawings 90%+ complete, scope fully defined	Lump Sum (Fixed Price)	AIA A101-2017	Contractor
Drawings 50–90% complete, fast-track start needed	Cost-Plus + GMP	AIA A102-2017	Contractor above GMP ceiling
Drawings under 50% complete, scope still evolving	Cost-Plus, No GMP	AIA A103-2017	Owner (fully)
Infrastructure with variable final quantities (roads, utilities)	Unit Price	Custom / ConsensusDocs	Shared by quantity
Emergency repair, exploratory demolition, or early mobilization	Time and Materials (T&M)	Custom	Owner
Single-point accountability, fast delivery	Design-Build	AIA A141-2014	Contractor (integrated)

The single most expensive contracting mistake owners make is choosing a lump-sum contract before design is complete, then being surprised by change orders that nullify the fixed price. Research published in the journal Sustainability (Asiedu & Adaku, 2019) found that poor contract planning and change-order mismanagement together explain approximately 70% of cost overruns on public construction projects. Contractors, meanwhile, often add a 5–15% contingency to lump-sum bids precisely to price the risk of incomplete drawings — meaning the owner pays for the uncertainty either way.

For owners who need price certainty but cannot wait for 100% design completion, a cost-plus with GMP is typically the better answer: the contractor's fee is transparent, savings below the GMP can be shared, and the ceiling caps worst-case owner exposure.

A Worked Example: One Project, Three Contracts, Three Very Different Bills

Consider a $900,000 commercial office fit-out. The architect has delivered 65% design documents — enough to describe the general scope but with mechanical, electrical, and plumbing (MEP) coordination still unresolved.

Scenario A — Lump Sum at 65% design: The contractor prices risk into the bid. The contract is signed at $900,000. During construction, 22 Requests for Information (RFIs) reveal uncoordinated MEP drawings. The contractor submits $135,000 in change orders — all legitimate, all owner-approved because the gaps were real. Final cost: $1,035,000 (15% over the signed price).

Scenario B — Cost-Plus with GMP negotiated after 95% design: The owner delays signing four weeks to reach 95% design completion. The contractor sets a GMP of $945,000 (cost estimate of $858,000 + 10% fee). The MEP coordination issues that would have become RFIs are caught in design review and resolved before bid. Final cost: $921,000 — under the GMP, with a 50/50 savings split returning $12,000 to the owner. Total owner cost: $909,000.

Scenario C — Cost-Plus without a GMP at 65% design: Same early start as Scenario A. No ceiling on owner cost. The same $135,000 in unresolved MEP scope flows through as reimbursable cost. Owner pays the $900,000 estimate plus the contractor's 10% fee on actual costs, plus the unresolved scope. Final cost: $1,068,000.

The difference between the best and worst outcome is $159,000 — not from contractor dishonesty or bad luck, but purely from contract structure selected at signing. Spending four weeks on design before executing the contract was worth $126,000 in this example.

What Clauses Must Every Construction Contract Include?

Regardless of contract type, these provisions are non-negotiable. Missing any one of them converts ordinary project friction into formal disputes.

1. Scope of Work A construction contract's scope must reference specific drawings and specifications by revision number and date. "Generally as shown on plans" is not enforceable. Any item not described — even if obvious — becomes a change-order candidate.

2. Contract Price and Schedule of Values The price and its breakdown into a schedule of values sets the baseline for every progress payment application. Under AIA A201-2017 § 9.2, the contractor must submit a schedule of values before the first payment application; the architect certifies it as a precondition to payment.

3. Change Order Process Specify: who initiates, who approves, the maximum number of days to respond, and what happens if a party fails to respond. California's SB 440 (the Private Works Change Order Fair Payment Act, effective January 1, 2026) establishes statutory deadlines for large private projects that cannot be waived by contract. Review your payment terms clause alongside this provision.

4. Progress Payments and Retainage Progress payments are typically submitted monthly against the schedule of values. Retainage — the holdback withheld as security — is now legally capped at 5% in California (Cal. Civ. Code § 8811) and New York (N.Y. Gen. Bus. Law § 757) for contracts executed after those statutes took effect. Both laws require the cap to flow down to all subcontractor tiers.

5. Lien Waiver Procedure Require conditional lien waivers from the general contractor and all listed subcontractors with each payment application, and unconditional waivers once payment has cleared. In California, Texas, Nevada, and Florida, lien waivers must follow statutory form; non-compliant language can render the waiver invalid or overbroad.

6. Liquidated Damages A liquidated damages clause specifies a pre-agreed daily dollar penalty for each day the contractor misses the completion date. Courts will enforce liquidated damages provisions if the stated amount is a reasonable pre-estimate of delay costs — not a penalty. For commercial projects, common rates range from $500 to $5,000 per calendar day depending on the owner's carrying costs and lost revenue.

7. Indemnification The scope of indemnification — who defends whom against third-party claims — is heavily regulated by state law. New York's General Obligations Law § 5-322.1 voids any construction contract provision requiring a contractor to indemnify an owner against the owner's own sole negligence. California Civil Code § 2782 contains similar restrictions on broad-form indemnification in construction agreements. Read your indemnification clause carefully before signing.

8. Force Majeure Post-pandemic contracts now routinely specify whether material price escalation, supply chain delays, and extreme weather events qualify as force majeure excusing delay. Courts in most U.S. jurisdictions have held that COVID-19 supply disruptions were not force majeure events under pre-2020 boilerplate language that limited the clause to "acts of God." Explicit, updated force majeure language is essential in new construction agreements.

9. Dispute Resolution AIA A201-2017 requires the parties to attempt mediation before filing for arbitration or commencing litigation. Consider adding a "project neutral" clause — a standing neutral expert who issues non-binding (or binding) interim decisions during construction, preventing disputes from freezing project progress. The average U.S. construction dispute in 2022 was valued at $42.8 million and took 13.6 months to resolve; a project neutral costs a fraction of that.

10. Termination Include both termination for cause (contractor default, owner non-payment) and termination for convenience. A termination-for-convenience clause allows either party to exit the contract without proving breach, limiting the terminating party's exposure to the cost of work completed plus overhead and a negotiated fee — rather than lost profits on the entire remaining contract.

2026 Law Changes Every Construction Party Needs to Know

Jurisdiction	Law	What Changed	Effective Date
California	SB 61 (Cal. Civ. Code § 8811)	5% mandatory retention cap on most private contracts; applies to all subcontract tiers	January 1, 2026
California	SB 440 (Private Works Change Order Fair Payment Act)	Standardized claim submission and dispute timelines for large private projects; sunsets January 1, 2030	January 1, 2026
California	AB 1327	Homeowners may cancel home improvement contracts within 3 days via email	January 1, 2026
New York	N.Y. Gen. Bus. Law § 757 (Prompt Payment Act amendment)	Any retainage exceeding 5% in private contracts is void — courts will not reduce to 5%, they will void the clause entirely	December 19, 2025
New York	Amended CPLR § 1007 (AVOID Act)	Rigid deadlines for filing third-party actions in construction litigation	April 18, 2026
North Carolina	S.L. 2026-9 (amending G.S. 143-128)	Separate trade specifications now required on all public building construction contracts regardless of dollar amount	June 19, 2026

These are not hypothetical risks. A New York private construction contract signed after December 19, 2025 with a 10% retainage clause does not become a 5% retainage contract by operation of law — the retainage provision is void in its entirety, potentially leaving the owner with no retainage protection if the clause is not severable from the rest of the payment terms.

How to Draft or Review a Construction Contract

Use this process whether you're drafting from scratch or reviewing a contractor's standard form.

1. Confirm design completion percentage before choosing contract type. Below 90%: do not sign a lump-sum contract. Negotiate cost-plus with GMP or delay signing.
2. Audit the scope of work against the drawing index. Every sheet referenced in the contract should exist and have a revision date. Gaps are future change orders.
3. Check retainage language against your state's current cap. California and New York owners and contractors should verify their forms have been updated for 2026 law changes.
4. Define the change order procedure precisely. Specify response deadlines (e.g., 14 days for owner response to contractor change-order proposals) and state that work does not proceed until the change order is signed.
5. Confirm insurance and bonding requirements are complete. Under AIA A201-2017 Article 11, builder's risk insurance, commercial general liability, and (on larger projects) performance and payment bonds all have specific coverage and endorsement requirements. Misaligned insurance requirements are a common cause of uncovered losses.
6. Insert a project neutral clause for projects above $500,000. Name a specific individual or designate a process for selecting one at project start — not after a dispute arises.
7. Review with a licensed construction attorney before signing. A contract review session with counsel typically costs far less than a single unresolved change-order dispute.

For straightforward contractor-owner relationships, Pactlio can generate a contractor agreement or services agreement as a starting point. For multi-party engagements spanning design, general contracting, and subcontractor tiers, a master services agreement can govern the framework with project-specific statements of work attached. All Pactlio drafts should be reviewed and tailored by a licensed construction attorney before execution.

Common Mistakes to Avoid

• Signing a lump-sum contract before drawings are complete. The "fixed price" becomes a floor, not a ceiling, once change orders begin flowing.
• Using a 10% retainage clause in California or New York after 2025. The clause is void — not reduced. The owner may end up with zero retainage protection.
• Accepting a broad lien waiver form without reading it. A broadly worded waiver can release rights to pending change orders, unpaid retainage, and delay damages beyond the payment actually received.
• Omitting a written change order requirement. Verbal authorizations for extra work are routinely disputed. Courts in most states require written change orders; oral modifications may not be enforceable.
• Specifying liquidated damages without calculating them. A daily rate plucked from a prior contract without basis in actual delay costs may be struck as an unenforceable penalty.
• Failing to flow down contract terms to subcontractors. The 5% retainage caps in California and New York explicitly require flow-down to all subcontract tiers. A GC who withholds 10% from subs while accepting 5% from the owner is in violation of state law.

Sources

• California SB 61 (Cal. Civ. Code § 8811): https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202520260SB61
• California SB 440 (Private Works Change Order Fair Payment Act): https://www.hansonbridgett.com/publications/251230_8187_construction-laws-2026
• New York General Business Law § 757 (Prompt Payment Act, 2025 amendment): https://andersonkill.com/article/essential-contract-considerations-for-construction-projects-in-2026/
• New York General Obligations Law § 5-322.1: https://andersonkill.com/article/essential-contract-considerations-for-construction-projects-in-2026/
• North Carolina S.L. 2026-9 (G.S. 143-128 amendments): https://canons.sog.unc.edu/blog/2026/06/24/legislative-changes-affecting-local-government-building-construction-contracts/
• AIA Document A101-2017 (Owner-Contractor, Stipulated Sum): https://store.aia.org/products/a101-2017-owner-contractor-standard-agreement
• AIA Document A201-2017 (General Conditions of the Contract for Construction): https://help.aiacontracts.com/hc/en-us/articles/1500010259162
• Construction cost overrun statistics (Flyvbjerg 2002; SmartPM): https://budgetoverrun.com/construction
• Construction dispute statistics — average US dispute value $42.8M, 13.6 months (Arcadis 2022): https://www.planradar.com/us/construction-litigation-and-disputes/
• Cost overruns: contract planning and change orders explain ~70% (Asiedu & Adaku, 2019 via MDPI): https://www.mdpi.com/2071-1050/17/5/2119
• Top causes of construction disputes (Arcadis / Construction Dive): https://www.constructiondive.com/news/the-dotted-line-how-to-avoid-skyrocketing-dispute-costs/691927/
• Federal Acquisition Regulation Part 36 — Construction Contracts: https://www.acquisition.gov/far/part-36
• Retainage law overview: https://constructioncoverage.com/glossary/retainage

This article is general information, not legal advice. Laws vary by jurisdiction. Pactlio generates professional drafts for review — have a licensed attorney review anything important.