Who must sign the addendum?

All parties who are bound by the addendum’s terms should sign — typically the property owner, contractor, and any financing party whose consent is required. Authorized signatories and printed names should be included for attribution.

Does the addendum need to be notarized?

Notarization is not universally required for a window addendum, but some states or contract types may require notarized signatures for certain real estate or financing documents. Check local rules or lender requirements.

Can the addendum change the original contract price?

Yes. The addendum can modify price and payment terms if both parties agree. Include explicit payment amounts and tie them to milestones to avoid ambiguity over invoicing.

How are warranty claims handled?

Detail warranty coverage, claim procedures, and notice periods in the addendum. Specify who pays for diagnostics and repairs when defects appear within the warranty period.

What if work needs to be changed after signing?

Use a written amendment signed by the same parties. Avoid oral change orders; document scope, price, and schedule updates to preserve enforceability and payment rights.

Is an electronic signature valid?

Electronic signatures are generally enforceable under the ESIGN Act (15 U.S.C. ch. 96) and UETA (adopted in most states). Exceptions exist for certain testamentary documents and some court filings; verify applicable state law.

Electronic Signature
Templates
Miscellaneous
Window Installation Addendum

Window Installation Addendum

This template is fully customizable. Edit the text, fill out the fields, and send it for signature. Give it a try!

WINDOW INSTALLATION ADDENDUM

Addendum Number: Effective Date:

Original Agreement Date: Original Agreement Reference/Number:

Project / Property Address:

RECITALS

WHEREAS, Client Name: and Contractor Name: entered into the Original Agreement referenced above governing window and exterior improvements at the Project Address; and

WHEREAS, the parties desire to modify the Original Agreement to include the supply, removal (if applicable), and installation of windows and related work as set forth in this Addendum; and

WHEREAS, the parties intend that the terms of this Addendum shall supplement and, in the event of any conflict, control over the Original Agreement to the extent explicitly stated herein.

SCOPE OF WORK

The Contractor shall furnish all labor, materials, equipment, supervision and permits necessary to complete the following window installation work in a good and workmanlike manner in accordance with applicable codes and industry standards.

Detailed Scope of Work (describe locations, removal, flashing, finishes, and any related carpentry) Itemized Window Schedule (complete each applicable line)

Quantity

Description (type, size, frame, glazing)

Unit Price

Line Total

(Complete additional lines as needed; parties may attach an additional schedule if more items are required.)

PAYMENT TERMS

Total Addendum Price: $. This amount represents the total consideration for the work described in this Addendum unless modified by written Change Order executed by both parties.

Payment Schedule: Deposit of $ due within days of Addendum Effective Date. Remaining balance of $ due upon completion and final acceptance, unless otherwise agreed in writing.

Late Payment: Unpaid amounts not received within days after invoice due date shall accrue interest at per month (or the maximum lawful rate), and Contractor may suspend work after providing written notice of intent to suspend.

SCHEDULE; TERM; TERMINATION

Commencement Date: . Substantial Completion Target Date: .

Notice to Cure / Termination: Either party may terminate this Addendum for material breach if the breaching party fails to cure such breach within calendar days after receipt of written notice specifying the breach. Termination shall be without prejudice to any rights or remedies accrued prior to termination.

Effect of Termination: Upon termination for any reason, Contractor shall be entitled to payment for work performed, materials delivered, and reasonable demobilization costs, subject to setoff for Client's damages arising from Contractor's breach.

CONFIDENTIALITY

Each party shall treat as confidential all proprietary information, trade secrets, pricing, and non-public technical or business information disclosed in connection with this Addendum. Confidential information shall not include information that is generally known to the public or rightfully received from a third party without restriction. The receiving party shall not disclose confidential information except to its employees, subcontractors or advisors who have a need to know and are bound by confidentiality obligations no less protective than those herein.

PERMITS, INSPECTIONS AND WARRANTIES

Permits and Inspections: Contractor shall obtain and pay for all permits and arrange inspections required by local authorities for the window installation unless otherwise agreed in writing. Client shall provide reasonably necessary access to the property during normal working hours.

Warranty: Contractor warrants labor and installation workmanship for months from date of substantial completion and warrants that materials supplied are as specified and free from manufacturer defects to the extent of the manufacturers' warranties. Any additional warranty terms must be set forth in writing and signed by both parties.

INSPECTION, ACCEPTANCE AND CHANGE ORDERS

Inspection & Acceptance: Upon completion, Contractor shall notify Client to inspect the work. Client shall promptly inspect and provide written notice of any nonconforming work within days. Failure to provide timely notice constitutes acceptance.

Change Orders: Any change to the Scope of Work or Price shall be by written Change Order signed by both parties, which shall state any adjustments to the Contract Sum and the schedule.

GOVERNING LAW

This Addendum shall be governed by and construed in accordance with the laws of the State of without regard to its conflict of law principles.

ENTIRE AGREEMENT

This Addendum, together with the Original Agreement and any written Change Orders, constitutes the entire agreement between the parties with respect to the subject matter hereof and supersedes all prior negotiations, proposals and representations, whether written or oral. In the event of any conflict between this Addendum and the Original Agreement, the terms of this Addendum shall prevail.

MISCELLANEOUS PROVISIONS

Independent Contractor Relationship: Contractor is an independent contractor and shall be responsible for payment of all taxes and contributions with respect to its employees and subcontractors. Nothing in this Addendum creates an employment, agency, partnership or joint venture relationship between the parties.

Assignment: Neither party may assign its rights or delegate its duties under this Addendum without the prior written consent of the other party, except that Contractor may assign receivables.

SIGNATURES

Client / Homeowner

Printed Name:

By (Signature):

Date:

Contractor / Installer

Printed Name:

By (Signature):

Date:

What the Window Installation Addendum Is

A Window Installation Addendum is a supplemental agreement attached to a primary contract (for example, a purchase agreement, lease, or contract for services) that records specific terms for replacing or installing windows. It defines scope of work, materials, payment terms, scheduling, warranty, access and damage responsibility, and signatory parties. The addendum clarifies changes to the original contract without rewriting the entire agreement and creates an enforceable record of the parties' revised obligations.

Why Add an Installation Addendum to Your Contract

A focused addendum reduces disputes by documenting scope, timelines, payment terms, and warranty specifics for window work. It preserves the original contract while providing clear, enforceable terms tied specifically to window installation.

Who Typically Uses a Window Installation Addendum

The Window Installation Addendum is used by property owners, general contractors, subcontractors, landlords, and property managers whenever window work changes the scope or cost of a primary agreement.

Residential property owners requesting replacement or upgrade of windows on an existing purchase or remodel contract.
General contractors hiring window subcontractors to document scope, lead times, and responsibility for site protection.
Landlords or property managers adding tenant-improvement window work into an existing lease or work order.

Use the addendum whenever window-specific details — product, access, warranty, or payment — are not fully covered by the underlying contract to avoid ambiguity.

Primary Signatories and Roles

Contractor — Project Lead

The contractor or window installer signs to confirm scope, price, warranty, and performance timelines. Their signature binds the installer to specified materials, installation standards, and cleanup responsibilities and should include company name and authorized signatory title.

Owner / Client

The property owner, landlord, or authorized manager signs to accept the scope, cost, and schedule. The owner's signature confirms payment authorization, site access windows, and agreement to hold the contractor harmless for work performed under the addendum's terms.

Core Sections to Include in a Professional Addendum

A complete Window Installation Addendum organizes responsibilities, materials, schedule, payment, risk allocation, and warranty information so both parties understand obligations specific to window work.

Scope of Work

Describe removal, disposal, flashing, framing adjustments, trim work, finishes, and any demolition or repair included; cite applicable code or performance standards.

Materials and Specifications

List manufacturer, model, glass type (e.g., double-pane, low-E), U-factor, visible transmittance, finishes, and accessory components to prevent substitution disputes.

Schedule and Access

State start and completion dates, daily work hours, required site access, and any occupant relocation expectations or weather contingency plans.

Payment Terms

Specify fixed sums or line-item pricing, deposit amounts, progress payment milestones, retainage, and acceptable payment methods.

Warranties and Defects

Detail installer warranty period, manufacturer warranties, responsibilities for leaks or seal failure, and procedures for repair or replacement.

Liability and Cleanup

Allocate responsibility for damage to property, waste disposal, final cleanup, and insurance coverage requirements for the installer.

Step-by-Step: How to Complete the Addendum

Follow these ordered steps to prepare, review, and finalize a Window Installation Addendum tied to an existing contract.

01

Gather Documents: Collect the primary contract, project drawings, and material specs.
02

Draft Scope Details: Write measurable scope items and attach exhibits for complex work.
03

Agree Payment Terms: Confirm deposit, milestone payments, and retainage terms.
04

Execute and Distribute: Sign, date, and provide copies to all parties and contractors.

How to Configure an Online Addendum Workflow

Set up a digital workflow to reduce errors and create an auditable record for the addendum.

Field	Configuration
Addendum PDF	Upload final PDF with fillable fields or use a template
Signer Order	Set party signing sequence (owner -> contractor -> subcontractor)
Authentication	Enable email verification and optional SMS code for higher assurance
Audit Trail	Capture timestamp, IP address, and action log for each signer

Digital Signing and eSubmission Considerations

Use an eSignature platform that supports secure signing, audit trails, and the file formats you need.

File Types: PDF and DOCX are standard; ensure platform preserves PDF formatting
Integrations: Look for integrations with project management or storage tools (e.g., Procore, Box, Google Drive)
Authentication Options: Email, SMS, or knowledge-based authentication depending on risk

Maintain single-source final signed copies and export an audit report to store with contract records.

Where to Send or File the Completed Addendum

Identify distribution and filing targets to ensure the addendum is effective and accessible for enforcement or warranty claims.

Contract Folder: Attach executed addendum to the primary contract file (electronic and physical records)
Project Manager: Provide a signed copy to the onsite project manager and superintendent
Owner Records: Deliver a copy to the property owner or asset manager for accounting and warranty tracking
Permits & Inspectors: If required, submit scope changes to building department or inspector before work begins

Typical Timelines and Deadlines to Note

Window projects and addenda trigger scheduling and payment deadlines; document these dates clearly to avoid disputes and delay claims.

Effective Date:

Enter effective MM/DD/YYYY; governs when work and obligations begin

Start Date:

Specify planned work start to coordinate permits and deliveries

Completion Date:

State expected completion or milestone completion dates

Payment Due Dates:

List specific due dates tied to milestones or inspection

Warranty Notice Window:

Define notice period for defect claims under warranty

Key Milestones from Agreement to Final Acceptance

Track major processing stages so parties know when obligations and inspections occur.

01

Addendum Execution

All parties sign and date the addendum to bind terms.

02

Permit Submission

Submit required permit applications and await approvals where necessary.

03

Material Delivery

Order and receive specified windows and components on site.

04

Final Inspection

Owner or inspector confirms installation meets the addendum and building code.

Common Mistakes to Avoid

Failing to reference the primary contract precisely, causing ambiguity about which terms apply.
Using vague material descriptions that permit substitution without owner approval.
Not specifying payment milestones or retainage, leading to disputes over partial completion.
Skipping permit or inspection clauses and beginning work out of compliance with local codes.

Risks and Potential Consequences of an Incorrect Addendum

Contract Disputes: Ambiguous terms can trigger breach claims and litigation costs

Warranty Loss: Incorrect material or installation language can void manufacturer or installer warranties

Permit Violations: Omitting permit obligations can lead to stop-work orders or fines

Payment Delays: Unclear payment milestones may result in withheld funds and liens

Liability Exposure: Insufficient insurance or indemnity language increases financial risk for property damage

Recordkeeping Gaps: Missing executed copies hinder enforcement and warranty claims

Comparing eSignature Options for Executing the Addendum

Select an eSignature vendor that supports secure signing, audit trails, and integrations you need; this table compares starting pricing and key features for common options.

	signNow	DocuSign	Adobe Sign	PandaDoc	HelloSign
Starting Price	$8/user/mo	$15/user/mo	$14/user/mo	$19/user/mo	$15/user/mo
Free Trial	7-day free trial, no credit card	Verify	Verify	Verify	Verify
Bulk Send	Yes	Yes	Yes	Yes	No
Audit Trail	Yes	Yes	Yes	Yes	Yes

Practical Tips for Accurate, Efficient Completion

Adopt these practices to reduce revisions and ensure enforceable outcomes when using a Window Installation Addendum.

Use Attachments

Attach diagrams, product spec sheets, and photos to the addendum to eliminate ambiguity and prove the expected installation outcomes.

Include Acceptance Criteria

Define objective acceptance tests (e.g., water infiltration tests, square and plumb tolerances) to reduce subjective disputes.

Record Changes

Track any post-signature changes using written amendments signed by the same parties rather than informal emails.

Preserve Signed Copies

Store signed PDFs with the audit trail in a secure document repository and link them to the primary contract record.

Real-World Examples

Illustrative scenarios show how addenda resolve common issues without rewriting the main contract.

Case Study 1

A homeowner requested upgraded double-pane windows during a remodel

The contractor provided a line-item addendum with price and 60-day lead time
The signed addendum clarified cost allocation and warranty, preventing a later dispute over product substitution.

Case Study 2

A property manager needed unit-by-unit replacements after storm damage

The addendum specified phased scheduling and temporary tenant relocation terms
Clear sequencing and tenant notice language kept the project on schedule and provided documentation for insurance claims.

Frequently Asked Questions

Answers to common questions about preparing, signing, and enforcing a Window Installation Addendum.

Need help? Contact support

Who must sign the addendum?
All parties who are bound by the addendum’s terms should sign — typically the property owner, contractor, and any financing party whose consent is required. Authorized signatories and printed names should be included for attribution.
Does the addendum need to be notarized?
Notarization is not universally required for a window addendum, but some states or contract types may require notarized signatures for certain real estate or financing documents. Check local rules or lender requirements.
Can the addendum change the original contract price?
Yes. The addendum can modify price and payment terms if both parties agree. Include explicit payment amounts and tie them to milestones to avoid ambiguity over invoicing.
How are warranty claims handled?
Detail warranty coverage, claim procedures, and notice periods in the addendum. Specify who pays for diagnostics and repairs when defects appear within the warranty period.
What if work needs to be changed after signing?
Use a written amendment signed by the same parties. Avoid oral change orders; document scope, price, and schedule updates to preserve enforceability and payment rights.
Is an electronic signature valid?
Electronic signatures are generally enforceable under the ESIGN Act (15 U.S.C. ch. 96) and UETA (adopted in most states). Exceptions exist for certain testamentary documents and some court filings; verify applicable state law.

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