Preparing Party Wall Agreements for Duplex Owners and Developers

Are you subdividing a property into a duplex or triplex? Are you developing apartments or condominiums? Are you wondering how to allocate rights between owners or tenants regarding a shared wall—and how to avoid future disputes over maintenance or cost-sharing?

A well-drafted Party Wall Agreement provides structure, promotes cooperation, and reduces the risk of costly legal conflict between neighboring property owners. Geraghty Law Office (GLO) prepares custom agreements for homeowners, developers, and investors involved in buying, subdividing, or constructing shared-wall properties.

What Is a Party Wall?

A Party Wall is a shared wall or structural feature—such as a roof or utility connection—that separates independently owned or leased units. These are commonly found in duplexes, townhomes, condominiums, apartments, office buildings, and other attached structures. The defining feature of a Party Wall is that it serves a functional or structural purpose for both units.

Party Walls may straddle the boundary between parcels, with each owner holding title to the portion on their side and benefiting from an easement that allows mutual support and use. In other cases, the wall may sit entirely on one property but still support both units. Regardless of physical layout, the responsibility for maintenance and repairs is typically shared. Read our blog Sharing is Caring: Party Wall Agreements: Understanding Rights and Obligations for Owners for more information.

What Is a Party Wall Agreement?

A Party Wall Agreement, sometimes referred to as a Shared Facilities Agreement or Common Wall Agreement, is a legally binding contract between property owners who share a structural element. Its purpose is to prevent disputes by clearly defining each owner’s rights and responsibilities related to the shared structure.

These agreements typically address maintenance obligations, cost allocation, and procedures for making repairs or structural changes. They often grant easement rights so that one owner can enter the other’s property when necessary to inspect or maintain the shared wall. Mutual consent is usually required before making any structural alterations.

Party Wall Agreements are often drafted by a developer and recorded in the county land records before any units are sold, ensuring that the agreement becomes binding on future owners. In other cases, owners may choose to create or update a Party Wall Agreement after purchasing their properties. While not a substitute for a homeowners’ association, a Party Wall Agreement can serve a similar purpose by governing shared property and establishing procedures for dispute resolution—without ongoing monthly HOA fees.

Are Party Wall Agreements Binding on Future Owners?

Yes. When properly drafted and recorded, Party Wall Agreements are enforceable against future owners as covenants running with the land. In Colorado, these agreements bind successor owners if the original parties intended to bind future owners, the agreement relates to the use, value, or enjoyment of the property, and the agreement is recorded in the county land records.

While binding, Party Wall Agreements can generally be amended or terminated by mutual consent. Any changes must be documented in writing and recorded to remain legally enforceable. Well-drafted agreements also include mechanisms for dispute resolution—such as mediation or arbitration—to avoid escalation of minor issues into costly litigation.

Why You Need a Party Wall Agreement When Splitting a Duplex

If you are converting a property into a duplex, a Party Wall Agreement is a vital legal tool. It defines maintenance and cost-sharing obligations for shared elements like walls, roofs, and foundations. It provides access rights for inspections and repairs and sets expectations for handling future renovations or disputes.

Without an agreement, each owner is left without a clear legal framework—raising the risk of confusion, conflict, and financial exposure. A Party Wall Agreement also protects future buyers by giving them a defined understanding of their responsibilities. Without a homeowners’ association (HOA), the agreement serves as the only source of governance over shared areas.  It’s an essential part of ensuring cooperation between neighbors and long-term investment stability.

In other words, the goal of a Party Wall Agreement is to anticipate and solve disputes between parties before they ever happen. 

Common Issues Typically Addressed in a Party Wall Agreement

When drafting or reviewing a Party Wall Agreement, it’s important to understand the kinds of issues the document should thoughtfully address. While every agreement is tailored to the property at hand, most well-drafted agreements share a few critical features that help ensure long-term clarity and cooperation between neighboring owners.

First, the agreement should clearly define what elements are shared, often referred to as the common elements. These typically include shared walls and roofs, but may also extend to garages, driveways, walkways, and utility lines. By clearly identifying what is shared, the agreement eliminates confusion and reduces the chance of conflict.

The agreement should also describe how the common elements can be used and maintained. It should outline who is responsible for routine upkeep and what happens if one party causes damage. For example, general maintenance costs are typically shared equally, but if one owner causes damage through negligence—such as from a water leak or unauthorized construction—that owner may be responsible for the full cost of repair. In cases where utilities are shared, the agreement should set out a fair method of dividing those costs.

Next, the agreement should grant appropriate easements—legal rights that allow one owner limited access to the other’s property for specific purposes like making repairs or conducting inspections. Common easements include those for lateral support, utility maintenance, and right-of-way access.

Finally, a sound Party Wall Agreement must provide a process for resolving disputes. Even the best neighbors may eventually disagree, especially when deciding whether to replace a roof or how to interpret maintenance obligations. The agreement should lay out a procedure—such as requiring a vote, mediation, or arbitration—to resolve these conflicts efficiently. For two-unit properties like duplexes, the agreement should include a tie-break mechanism for situations where owners are deadlocked.

A Party Wall Agreement is more than a formality. It is a foundational document that protects both parties and fosters a cooperative environment for shared property ownership.

How GLO Can Help

At Geraghty Law Office, we help real estate investors, developers, and homeowners in Colorado navigate the legal complexities of shared ownership. Whether you are subdividing property, preparing to sell attached units, or looking to establish or review a Party Wall Agreement, we provide tailored legal support to safeguard your investment.

We draft clear, enforceable agreements that cover all essential terms—maintenance, access, alterations, cost-sharing, and dispute resolution. Our goal is to protect you from future liability and create a legal structure that supports long-term property value and neighbor cooperation.

And if you are considering purchasing a property that is subject to a Party Wall Agreement, or if you already own such a property and need help interpreting your rights and obligations, we review existing Party Wall Agreements to help clients understand their legal responsibilities, identify potential risks, and assess compliance with current law. To learn more about how GLO can help, read: Party Wall Agreements.

Please fill out an Intake Form to inquire about working with GLO.

GLO has prepared this blog to provide general information on legal issues that may be of interest. This blog does not provide legal advice for any specific situation and this does not create an attorney-client relationship between any reader and GLO or its attorneys. GLO engages clients only through specific fee arrangements and signed engagement letters. GLO does not guarantee any results.

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