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Producer and Patent Holder
of low-profile subduct risers for multistory buildings.

Low-Profile Subduct Riser (LSR)
U.S. Patent No. 8,267,759


Subduct Riser Manufacturing offers low-profile subduct risers made of 26 gauge galvanized steel. The LSR is beneficial in applications where a 22 inch subduct riser is necessary to maintain the fire and smoke rating of an exhaust shaft instead of using fire and smoke dampers. The LSR is IBC- and IMC-compliant for bathroom, kitchen, and clothes dryer exhaust shafts.


The LSR is available with female inlet connections of 4, 5, 6, 8 and 10 inches.  Surrounded by a 3/8 inch flange, the LSR attaches firmly to the inside wall of the exhaust shaft, eliminating the possibility of loose or disconnected risers. The LSR pro-vides the minimum 22 inch rise while maintaining a low profile. Using LSR risers as an alternative to conventional field-erected subducts results in lower velocities and less restriction in the main exhaust shaft allowing for smaller main shafts with less generated noise.  

LSR 04
LSR04 (inverted).png


V:  4"

L:  27"

W: 6" 

D:  2"

LSR 04 vs Conventional Subducts
LSR04 Diagram (inverted).png

The flow area through a 10" x 10"  is 52% larger than using tw LSR04s instead of two 4"  convential subducts

LSR 05
LSR05 (White).png


V:  5"

L:  30"

W: 9" 

D:  3.5"

LSR 06


V:  6"

L:  30"

W: 9" 

D:  3.5"

LSR06 (White).png
LSR 08


V:  8"

L:  32"

W: 12" 

D:  4.5"

LSR08 (White).png
LSR 10


V:  10"

L:  34"

W: 15" 

D:  6"

LSR10 (White).png
Features and Benefits
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