Construction Contracts 101: What Every Contractor Needs to Know

A handshake used to be enough. Your word was your bond, and the job got done.

Those days are gone.

Today, a solid construction contract is the single most important document on any job. It protects your business, guarantees you get paid, and gives you a clear path forward when things go sideways. And in construction, things always go sideways eventually.

Whether you are a general contractor running million-dollar commercial builds or a specialty sub doing residential remodels, understanding contracts is not optional. It is survival.

This guide covers everything you need to know: the main contract types, the clauses you cannot skip, the red flags that should make you walk away, and when it is time to bring in a lawyer.

Why Construction Contracts Matter More Than You Think

Here is the reality. About 60% of construction disputes come down to poorly written contracts or misunderstandings about what was agreed to. That is not a legal statistic you read in a textbook. That is what happens on real jobsites every single week.

A good contract does three things:

1. Defines exactly what you are building. No guessing, no assumptions.
2. Spells out how and when you get paid. Cash flow is everything in this business.
3. Creates a roadmap for problems. Because problems will come up.

Without a written contract, you are relying on memory, goodwill, and luck. None of those hold up in court.

The Four Main Types of Construction Contracts

Every construction contract falls into one of four categories. Each one shifts risk differently between the contractor and the owner. Understanding that risk is the key to picking the right contract for the right job.

1. Fixed Price (Lump Sum) Contracts

This is the most common contract type in residential and small commercial work. You agree to do the job for one set price. The owner knows exactly what they are paying, and you know exactly what you need to deliver.

How it works: You estimate the total cost of labor, materials, equipment, overhead, and profit. You give the owner one number. If you finish under budget, you keep the difference. If you go over, you eat the loss.

Best for: Projects with a clear, well-defined scope. Remodels with detailed plans. New builds where the specs are locked in. Repeat work where you know your costs cold.

Watch out for: Scope creep. If the plans are vague or incomplete, a fixed price contract can destroy your margins. You need detailed plans and a tight scope of work before you commit to a number.

The estimating connection: Your fixed price is only as good as your estimate. If your estimate is sloppy, your contract price will be wrong, and you will lose money. Tools like Projul’s estimating features help you build accurate estimates so your lump sum actually protects your profit.

2. Cost Plus Contracts

With cost plus, the owner pays for the actual cost of the work (labor, materials, equipment) plus a fee for your overhead and profit. That fee can be a flat amount or a percentage of costs.

How it works: You track every dollar spent on the job and bill the owner for those costs plus your agreed markup. The owner carries most of the financial risk because they are paying actual costs.

Best for: Renovation work where surprises are likely. Projects where the full scope is not clear at the start. Emergency repairs. Custom homes where the owner wants to make decisions as they go.

Watch out for: Owners getting nervous about the final number. Cost plus contracts need clear documentation and regular updates. If the owner feels like costs are running away, the relationship breaks down fast.

Pro tip: Set a guaranteed maximum price (GMP) on cost plus contracts when you can. This gives the owner a ceiling and gives you a target. It is a good middle ground.

3. Time and Materials (T&M) Contracts

T&M contracts pay you for the actual time your crew works plus the cost of materials. You set hourly or daily rates for each trade, and materials are billed at cost plus a markup.

How it works: You track hours by worker and bill for materials as they are used. The owner pays based on actual time and actual materials.

Best for: Small jobs, service work, repair projects, and situations where the scope is truly unknown. When a homeowner says “we will figure it out as we go,” T&M is often your safest bet.

Watch out for: Disputes over hours worked and material costs. Keep detailed daily logs. Take photos. Track everything. If you cannot prove the hours, you will not get paid for them.

4. Unit Price Contracts

Unit price contracts break the job into measurable units. You price each unit (per square foot, per linear foot, per cubic yard), and the final price depends on the actual quantities installed.

How it works: You bid a price per unit for each work item. As work is completed, quantities are measured and you are paid based on actual installed amounts.

Best for: Site work, paving, concrete, excavation, and any job where quantities are estimated but not exact. Government projects often use unit pricing.

Watch out for: Quantity overruns or underruns that throw off your overhead recovery. If the actual quantity is much less than estimated, your per-unit overhead allocation might not cover your fixed costs.

Essential Clauses Every Contractor Must Include

The contract type is the framework. The clauses are the details that protect you. Skip any of these and you are asking for trouble.

Scope of Work

This is the most important section of any construction contract. Period.

The scope of work defines exactly what you are building, what materials you are using, what quality standards apply, and where your responsibility ends. If it is not in the scope, it is not your problem.

What to include:

• Detailed description of all work to be performed
• Materials and specifications
• What is specifically excluded (this is just as important)
• Reference to plans and drawings by date and revision number
• Quality standards and code requirements

A vague scope of work is an invitation for the owner to expect more than you priced. Be specific. Be detailed. Leave nothing to interpretation.

Using Projul’s project management tools to organize your scope documentation keeps everything in one place. When a dispute comes up six months into the job, you need to pull up exactly what was agreed to, and you need it fast.

Payment Terms

You are in business to make money. Your contract needs to spell out exactly how and when that money shows up.

What to include:

• Payment schedule (progress payments, milestones, or schedule of values)
• Payment terms (net 30, net 15, due on receipt)
• Retainage percentage and release conditions
• Late payment penalties and interest rates
• How to handle disputed amounts (pay the undisputed portion)

Critical detail: Your contract should state that you have the right to stop work if payment is more than a set number of days late. Without this clause, you could be forced to keep working while the owner holds your money.

Setting up your invoicing through Projul ties your billing directly to your project milestones, which makes payment disputes much harder for owners to win.

Change Order Process

Change orders are where contractors make money or lose money. There is no in-between.

Your change order clause must cover:

• All changes require a written change order before work begins
• The change order must include the cost impact and schedule impact
• Both parties must sign before changed work starts
• No verbal change orders are valid

This is non-negotiable. If you start change order work without a signed authorization, you are gambling that the owner will pay for it later. Sometimes they do. Often they do not.

Dispute Resolution

When disagreements happen (and they will), your contract needs to tell both parties what to do next.

Common options:

• Negotiation first. Sit down and talk before anything formal happens.
• Mediation. A neutral third party helps you find common ground. Cheaper than litigation.
• Arbitration. A neutral party makes a binding decision. Faster than court but you give up your right to appeal.
• Litigation. Full court process. Expensive and slow but sometimes necessary.

Most construction contracts use a stepped approach: negotiate first, then mediate, then arbitrate or litigate. This keeps small problems from becoming expensive lawsuits.

Important: Specify which state’s laws govern the contract and where disputes will be heard. You do not want to fight a legal battle in another state.

Termination Clause

Sometimes a project needs to end early. Your contract should cover two types of termination:

Termination for cause: One party has failed to perform. The contract should list what counts as cause (non-payment, abandonment, material breach) and what notice is required before termination.

Termination for convenience: The owner can end the project at any time for any reason. This clause should require the owner to pay for all work completed, materials ordered, and a reasonable cancellation fee.

Without a termination clause, ending a project early becomes a legal mess.

Insurance and Indemnification

Your contract should specify:

• Minimum insurance requirements for all parties
• Types of coverage required (general liability, workers comp, auto, umbrella)
• Certificate of insurance requirements and additional insured status
• Who is responsible for what types of claims

Do not gloss over this section. One uninsured accident can bankrupt your company.

Schedule and Delays

Your schedule clause should address:

• Project start and completion dates
• Milestone dates for key phases
• What qualifies as an excusable delay (weather, force majeure, owner-caused delays)
• How delay claims are handled
• Liquidated damages for late completion (if applicable)

Make sure the contract distinguishes between delays you cause and delays caused by others. You should not be penalized for delays that are not your fault.

Red Flags That Should Make You Walk Away

Not every job is worth taking. Here are the warning signs that a contract (or a client) will cost you more than you make.

”We’ll figure out the details later”

If the scope is vague and the owner resists putting details in writing, run. Vague scopes lead to arguments, unpaid work, and claims.

Pay-if-paid clauses

These clauses say the GC only has to pay you after the owner pays the GC. If the owner goes bankrupt or refuses to pay, you get nothing. Pay-when-paid (which sets a reasonable timeframe) is slightly better, but pay-if-paid is a dealbreaker for most subs.

No retainage release date

If the contract says retainage is held but never says when it is released, that money might sit in someone else’s account forever. Insist on a specific release date tied to substantial completion or final completion.

Waiving lien rights upfront

Some contracts ask you to waive your mechanic’s lien rights before the work is done. Your lien rights are your strongest tool for getting paid. Never waive them in advance. Conditional lien waivers (tied to actual payment) are fine. Unconditional waivers before payment are not.

Unreasonable indemnification

If the contract asks you to indemnify the owner for problems you did not cause, push back. You should only be responsible for claims arising from your own work, not the owner’s negligence or someone else’s mistakes.

No change order process

If the contract does not address how changes are handled, every change becomes a fight. Walk away or add a change order clause before you sign.

Protecting Yourself: Best Practices for Every Job

Document everything

From day one, document every conversation, every decision, every change, and every problem. Photos, emails, daily logs, meeting notes. If it is not written down, it did not happen.

Projul’s project management features make this easy by giving your whole team one place to capture photos, notes, and documents tied directly to each project.

Read before you sign

This sounds obvious, but too many contractors sign contracts they have not fully read. Read every page. Understand every clause. If something does not make sense, ask about it before you sign.

Keep copies of everything

Signed contracts, change orders, payment applications, lien waivers, insurance certificates. Keep organized copies of everything, both digital and physical. When a dispute hits two years after the job is done, you need to find those documents.

Build your estimate right

Your contract is only as strong as the estimate behind it. If you underestimate a fixed price job, the best contract in the world will not save your profit margin. Take the time to build accurate, detailed estimates for every project.

Projul’s estimating tools help you build professional estimates with real cost data so your contract price reflects the actual cost of the work.

Know your lien rights

Mechanic’s lien laws vary by state, and the deadlines are strict. Missing a lien filing deadline by even one day can cost you your right to file. Know the rules in your state and track your deadlines.

Get insurance certificates before work starts

Do not let subs on your jobsite without current insurance certificates. If an uninsured sub gets hurt on your job, you are on the hook.

When You Need a Lawyer

You do not need a lawyer for every contract. But there are situations where legal review is not optional.

Call a construction attorney when:

• The project value is over $50,000
• The contract includes unusual risk allocation or indemnification
• You are working as a sub on a government project (prevailing wage, bonding requirements)
• The other party’s attorney drafted the contract (it is written to protect them, not you)
• You are entering a new market or contract type for the first time
• There is a dispute that negotiation and mediation have not resolved

A few hundred dollars for a contract review is cheap insurance against a six-figure dispute.

Finding the right attorney: Look for a lawyer who specializes in construction law, not a general practice attorney. Construction has its own rules, customs, and case law. You want someone who understands the industry.

Building Your Contract Template

Every contractor should have a solid contract template as a starting point. Here is how to build one:

1. Start with an industry standard form. AIA, ConsensusDocs, and AGC all publish standard construction contract forms. These have been tested in court and cover the major issues.
2. Customize for your business. Add your specific payment terms, change order process, insurance requirements, and dispute resolution preferences.
3. Have it reviewed. Pay a construction attorney to review your template once. Fix the issues they find.
4. Update regularly. Review your template at least once a year. Update it based on lessons learned from recent projects.
5. Customize the scope for each job. The template stays the same, but the scope of work should be written fresh for every project.

Putting It All Together

Construction contracts are not just legal paperwork. They are business tools that protect your company, define your relationships, and make sure you get paid for your work.

Here is your action plan:

1. Pick the right contract type for each project based on how well-defined the scope is.
2. Include all essential clauses. Do not skip any of the sections covered above.
3. Watch for red flags. If something feels wrong in a contract, it probably is.
4. Document everything from estimate to final payment.
5. Know when to call a lawyer. Some situations demand professional legal help.

The contractors who succeed long-term are not always the best builders. They are the ones who run their business like a business. And that starts with solid contracts.

Ready to tighten up your project documentation and estimating? Check out Projul’s pricing to see how the right software supports better contracts and better projects from the start.