Internal Chimney Seal


Get more range of coverage to stop the flow with Cretex’s newest line of mechanical chimney seals. The LSS Manhole Chimney Seal rubber sleeve is available in four widths to span up to 24 vertical inches of the chimney without using extensions. Ensure your investment is solid with our 50-year warranty
chimney seal


 Experience LESS HASSLE because our revolutionary LSS internal chimney seal is easier to install, and it has more range of coverage, requiring LESS TIME. In addition, the LSS seal is LESS EXPENSIVE than classic seals, and the elimination of extensions produces LESS INVENTORY. And finally, you will have LESS WORRY with our 50-year warranty.

The LSS Manhole Chimney Seal rubber sleeve is available in four widths to cover vertical heights from 0-24 inches. See our Manhole Measurement Worksheet for help with selecting a product.

chimney seal

HIGH GRADE RUBBER and expansion bands

The LSS sleeve conforms to the applicable material requirements of ASTM C-923. It has a minimum thickness of .130 inches for durability and resistance to tearing and puncturing. The one-piece channeled expansion bands are 1-3/4 inches wide and are fabricated from high-quality, corrosion-resistant, 16 gauge stainless steel. Check our Tech-Data Sheet for details.

manhole chimney seal

mechanical chimney seals cost the same as applied seals, but last 3.5 times longer

(ASCE) reported that a mechanical seal and an applied seal cost about the same, but mechanical manhole frame-chimney seals would last 3.5 times longer. Contact a Cretex representative to learn more about the LSS Internal Chimney Seal advantages for new construction and rehabilitation projects.

versatile and expandable

The LSS has a range of coverage for a vertical span of up to 24 inches without an extension. In addition, one size can fit a frame/chimney diameter range of up to 20%. View our specification sheet for more information..