How to Cut a Stainless Steel Flexible Chimney Liner

How to Cut a Stainless Steel Flexible Chimney Liner

Proper Tools for Cutting the Flexible Liner

When installing a new chimney liner, most likely you will need to cut your liner to the correct size. This is a job you can handle with proper preparation.

A good pair of gloves and safety glasses are essential; the liner will be sharp! If cutting it on the ground, wrap duct tape around the cut end for your safety.

The best tool to use, for the quickest and cleanest cut, is a grinder with an abrasive metal cut off wheel. Circular saws with metal cutting blades will also do a great job. A Sawzall (reciprocating saw) with a metal blade will work, but it does vibrate and the finish cuts aren't always the prettiest; but when everything is attached, the cut end of the liner is not visible anyway. Of course, a new blade in a hack saw, or a pair of heavy duty metal snips, will get it done too.

You'll need to decide on whether to cut the liner before or after the installation, as there are advantages and disadvantages to both options.

Cutting the Flexible Liner

If you plan on cutting it before installing, you will be able to work more comfortably. Cutting it on the ground it allows for stable footing and extra hands if needed. But you will need VERY accurate measurements for the total length. Make sure to add 3 inches above the top of the chimney for the top plate collar that secures the liner. Once you are sure of your measurements, mark the liner. I suggest wrapping a piece of duct tape or masking tape at that mark to ensure a straighter cut. DO NOT try to follow one of the seams on a flexible liner while cutting, you could end up 3 inches off by the time you get all the way around!

If you plan on cutting the liner after the installation (my preference), the collar on the top plate gives you a good reference point for a straight cut. Everything will be connected and there will be no doubt if you will have enough liner. Make sure you have a long enough extension cord, if you are going to need one, and if you are working from a ladder, do not try to over reach.

The amount of liner left above the top plate collar should be at a minimum. There should be at least 5 inches of space between the end of the liner and the chimney cap lid for proper ventilation.

As always, if you have any questions or problems, feel free to give us a call. We're happy to help!

DIY Center

(AKA ‘The Rockford Files’)

From video tutorials to product walkthroughs, we have a variety of DIY resources just for you! Click the button below to view our entire library.


Need Help?

We are here to answer all of your questions




Our 316Ti flexible chimney liner and chimney liner components have passed the rigorous testing at the Underwriters Laboratories with best in class status and are UL Listed. So if you are looking for UL listed chimney liner sold directly to homeowners, then look no further than Rockford Chimney

Customer Testimonials

Back in July you gave me excellent advice re. sizing/purchasing a flue liner for the chimney associated with my wood stove. I'd like to thank you once agai... More

—AE Northfield, MN

A few weeks ago I ordered a chimney liner system for my fireplace insert. Your salesman recommended the liner system plus the insulating blanket. I just wa... More

—AH Happy customer

Just got around to installing my new smooth flexible liner and deluxe terra cotta cap (wow). The quality of your product is second to none. Very pleased an... More

—B.B. from Massachusetts

Thanks so much for the great tech service from Dennis, very knowledgable, friendly and proffessional.Your website is the best, beats your competition by fa... More

—Bill in Knoxville

Sue and Dennis, I received the final part of my order yesterday (the chimney cap that actually fits over the chimney chase). It looks wonderfu... More


Hello, I was shopping for an fireplace insert and called RCS to ask why they were so much cheaper than my local guy, the reply was " we sell thousand of th... More

—Chris, PA.