By Johnathan Mason, Ace Chimney Service.
Attached homes complicate a simple question: whose chimney is it? In townhomes and duplexes the flues often run inside a shared chase, the exterior may belong to an association, and the appliance inside belongs to you. That split is where maintenance falls through the gap. It comes up regularly in Lake in the Hills, where attached housing is common.
How these systems are usually built
Most attached homes of this type use factory-built fireplaces venting through metal pipe inside a wood-framed chase, finished in siding, with a sheet-metal chase cover on top. Several units may share a single chase structure, each with its own flue running up inside it. The pipes are separate; the box around them may not be.
Where the responsibility line usually sits
As a general pattern, the appliance, the flue serving your unit, and everything inside your walls is the owner’s. The chase structure, the siding, the cover, and the roof are commonly the association’s. But this is set by your governing documents, not by convention, and the documents disagree with each other from one community to the next. Read yours before assuming, and get any answer in writing.
What goes wrong in shared chases
The chase cover is the big one. A flat or nearly flat sheet-metal lid ponds water, rusts through, and then drips down the outside of the flue pipes inside the chase — rotting framing, staining ceilings, and corroding the pipe. Because it is on top of a shared structure, nobody’s unit obviously owns it, and it goes years without being looked at. After that: missing or damaged caps letting rain and animals in, and gaps in the chase framing that give birds and squirrels access to every pipe in the run.
The neighbour effect
In attached construction your neighbour’s maintenance affects you. A blocked flue two doors down does not put smoke in your living room, but a rotting shared chase, an animal infestation, or water tracking through common framing absolutely reaches you. Coordinating an inspection across the building is more effective than each owner acting alone, and it is usually cheaper per unit as well.
What an inspection covers
Your flue, your appliance, the cap, the chase cover condition, and the accessible parts of the chase. Factory-built systems need listed replacement parts, not improvised ones — that matters when a cover or cap is being replaced on someone else’s budget. Our chimney inspection page explains the process, and caps and covers covers the hardware.
Ace Chimney Service works with individual owners and associations. 29 years, insured and bonded, price up front, seven days a week 7 AM to 7 PM across Crystal Lake and McHenry County. Call (815) 320-0883.
Frequently asked questions
Who pays for chimney work in a townhome?
It depends on the governing documents. Interiors and the appliance are usually the owner’s; the chase exterior and cover are often the association’s.
Do neighbours share a flue?
Rarely. Each unit normally has its own flue, though several flues may run inside one shared chase.
What is a chase cover?
The metal lid on top of the framed chase. Rusted covers are the leading cause of water damage in these systems.
Can my neighbour’s chimney cause my leak?
Water entering a shared chase can travel through common framing, so yes, in shared structures it happens.
Does the association need to approve the work?
For anything on the exterior or the chase, usually yes. Check before scheduling.
Can several units be inspected in one visit?
Yes, and coordinating a building is generally more efficient than booking unit by unit.
Are prefab fireplaces in townhomes swept the same way?
Metal flues collect creosote too and are swept with appropriate brushes for the liner type.
What if the chase cover needs replacing?
It should be replaced with a properly sized, sloped cover in a durable material, not patched with sealant.
Published September 22, 2026