Before a single window gets removed from its frame, you should have a signed contract in hand. A detailed, written agreement protects you if work goes wrong, prices shift, or disputes arise — and it tells you a lot about the professionalism of the contractor you're hiring. Here's what that document needs to cover.
A verbal quote or a one-page estimate is not a contract. Contracts create legal obligations on both sides. Without one, you have little recourse if the installer uses different materials than discussed, the job runs months over schedule, or damage occurs during installation. The more specific the contract, the less room there is for disagreement later.
The contract should clearly name:
Never sign a contract from a business that can't provide a verifiable address and license number. These details matter if you ever need to file a complaint or pursue a legal claim.
This is the core of the contract — and the section most likely to cause disputes if it's vague. It should specify:
If you agreed on a specific product during the sales conversation, it should appear by name in the contract — not just a generic description. Substitutions happen, and a vague scope of work makes them difficult to challenge.
Many homeowners assume this is included. It often isn't by default. The contract should explicitly state:
In some cases — particularly with older homes — existing windows may contain lead paint or other hazardous materials. How that situation will be handled should be addressed before work begins, not during it.
Your contract should state:
Skipping permits might seem like a way to cut costs, but unpermitted work can create problems when you sell your home or file an insurance claim.
The contract should include:
"We'll get to it soon" is not a timeline. Vague scheduling is one of the most common sources of contractor disputes.
The pricing section should be explicit:
| Item | What to Look For |
|---|---|
| Total contract price | Full amount, including labor and materials |
| Deposit amount | What percentage is due upfront |
| Progress payments | When additional payments are triggered |
| Final payment | Due upon completion or inspection |
| Change order process | How cost increases are approved and documented |
Be cautious of contracts that require a large percentage of the total price as an upfront deposit. A reasonable deposit structure depends on the size of the job, but payment should generally track completion — not front-load in the contractor's favor.
Change orders deserve special attention. Any work added or changed after the contract is signed should require a written amendment with a new price before work proceeds.
There are typically two separate warranties involved in a window installation:
The contract should spell out the duration of each, what's covered, what voids coverage, and the process for making a claim. A manufacturer's warranty doesn't help you if the installer's work caused the problem — and an installer's warranty doesn't help if the window itself is defective.
Before signing, confirm the contract addresses:
Ask to see certificates of insurance before work begins. A reputable contractor provides them without hesitation.
The contract should specify:
"Leave the site in broom-clean condition" or equivalent language is reasonable to expect in writing.
Even well-intentioned projects can hit snags. The contract should include:
Read the full contract before signing — every page. If something is unclear, ask for clarification in writing. If something you agreed to verbally isn't in the document, have it added before you sign. Once the contract is executed, keep a copy in a safe place alongside your receipts, warranty documentation, and permit records.
The right contract protects both sides. A contractor who resists putting details in writing is telling you something worth hearing.
