What Is FuranFlex® and Why Should You Use It in Your Building’s Chimney?
When it comes to chimney liners in commercial and multi-story buildings, the choice of material can significantly impact long-term safety, efficiency, and maintenance costs.
One of the most advanced options on the market today is FuranFlex®, a composite chimney lining system engineered for modern performance and designed to overcome the limitations of traditional liners.
At United Chimney, we’ve trusted and installed FuranFlex® for years across New York City’s most complex buildings, including prewar properties, high-rises, and historic structures, and here’s why we think it’s a game-changer.
What Is FuranFlex®?
FuranFlex® is a resin-based, joint-free composite chimney liner that hardens to the strength of steel. It’s flexible during installation and conforms perfectly to the shape of your flue. Once steam-cured, it creates a corrosion-resistant, airtight interior that can withstand high temperatures and acidic condensate produced by today’s high-efficiency heating systems.
Unlike metal liners, which can corrode or require wall demolition for access, FuranFlex® slides into place and adapts to virtually any chimney configuration; round, square, oval, or irregular.
Key Benefits of FuranFlex® for Building Owners
Seamless and Airtight
FuranFlex® installs as one continuous liner, no joints, no gaps, no weak points, reducing the risk of dangerous gas leaks or compromised draft performance.
No Demolition Required
Because it’s flexible during installation, there’s no need to break walls or brickwork, making it ideal for occupied buildings and landmark structures where preservation matters.
Corrosion and Heat Resistant
Designed to handle the acidic condensate from modern gas and oil boilers, FuranFlex® is backed by a 25-year corrosion warranty. It also holds up under high temperatures, making it safe for demanding venting systems.
Ideal for Complex or Historic Buildings
Whether your flue runs 10 floors through a prewar apartment or curves around an elevator shaft in a commercial property, FuranFlex® can adapt to tight, angled, or variable routes that metal liners can’t reach.
Why Chimneys in NYC Are a Perfect Fit for FuranFlex®
In cities like New York, many buildings, especially prewar or mixed-use properties, have aging masonry, odd-shaped flues, or shared venting systems. These factors make it nearly impossible to use rigid liners without invasive construction.
FuranFlex® solves this challenge by:
- Navigating complex, multi-story paths
- Preserving original architectural elements
- Providing a modern, code-compliant solution without heavy equipment or building-wide disruption
The FuranFlex® Installation Process at United Chimney
As certified installers, our team handles the entire process:
- Video Inspection – We scan and assess your flue to determine size, shape, and challenges.
- Liner Placement – A soft FuranFlex® tube is inserted into the flue.
- Steam Expansion – The liner is expanded with steam, molding to the exact internal shape.
- Curing – It hardens into a rigid, steel-strong shell.
- Final Testing – We perform pressure tests and a final scan to confirm structural integrity.
The entire process is often completed in just one day, making it one of the most efficient options for busy buildings.
Why United Chimney?
With over 30 years of experience working in NYC and the surrounding boroughs, we understand the structural and compliance challenges that building owners face. Our team doesn’t just install liners, we provide turnkey venting solutions backed by engineering insight, DOB compliance knowledge, and unmatched workmanship.
FuranFlex® is only as effective as the team installing it and that’s where United Chimney excels.
Ready to Upgrade Your Chimney Liner?
If your building has an aging flue, corrosion issues, or you’re upgrading to high-efficiency boilers, FuranFlex® is the smart, modern choice. And with United Chimney’s certified team leading the way, you get precision, safety, and peace of mind from start to finish.
Contact us today to schedule an inspection and see if FuranFlex® is the right fit for your building’s venting system.
Douglas Acker
Douglas Acker is the founder and owner of United Chimney Corp., bringing over 30 years of hands-on experience in chimney, flue, and venting systems across New York City and the tri-state area. Known for his deep technical expertise and commitment to safety, Doug has become a trusted resource for property managers, engineers, and building owners tackling complex commercial and residential venting challenges. Under his leadership, United Chimney has earned a reputation for turnkey service, problem-solving, and code compliance excellence in even the most demanding building environments.