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LFM 1 (800) 237-5791
FSI 1 (800) 953-8202

Fiberglass Manhole Risers


LFM has been building quality fiberglass reinforced manholes, manhole liners, wetwells and wetwell liners since 1982. We utilize the latest in chop and filament winding equipment, herefore providing our customers with the highest quality fiberglass products on the market today.

Quality Built Right-In

LFM incorporates a comprehensive in-plant testing and quality control program. This insures complete and consistent workmanship in all of our fiberglass products. Each manhole that we build is inspected and tested before it is released for shipping. Our testing procedures
include wall thickness reports, raw material analysis, and continuous chemical analysis reports. Individual testing reports are recorded and maintained at our office and are available upon request.


Our fiberglass manholes are light-weight, greatly reducing delivery and installation costs. Due to the anticorrosive nature of LFM's fiberglass manholes, repair and replacement costs due to corrosion are reduced as well.

fiberglass manhole riser

Available Diameters

LFM builds fiberglass manholes to your specified dimensions with the following diameters available from 36 inches through 14 feet. Depths are available by the half foot from 2' through 40'. We manufacture several different wall thicknesses for different load, depth and diameter specifications. Contact your LFM sales representative to find which dimensions best suit your needs.


Fiberglass manholes by LFM can be built with pipe connectors and adaptors already in place. We offer a wide range of pipe stubouts on our manholes from 4" diameter all the way to 48" diameter for larger applications. We also offer Kor-N-SealTM boots, as well as connectors from other manufacturers, from 4" through 24" diameters. LFM's manhole risers can include an FRP anti-flotation bottom flange and a fiberglass bench area with appropriate connecting coupling to join with the pipe manufacturer's "tee" base section.

Summary of Test Results
Tests Performed Average Results
Stiffness 5% Deflection @ 2.45 lbs. / in.2
10% Deflection @ 2.28 lbs. / in.2
Material Composition 54.25 wt. % Resin
Compressive Strength Transverse: 22,700 psi
Longitudinal: 10,500 psi
Flexural Strength Transverse: 56,000 psi
Longitudinal: 11,700 psi
Modulus Transverse: 2,084,000 psi
Longitudinal: 1,114,000 psi
Load Rating 24,000 lbs. - 0.157” Deflection
40,000 lbs. - No Damage
Barcol Hardness Cylinder: 43.1
Reducer: 41.0
Wall Thickness Cylinder: 0.308
Soundness No Leaks Detected at 5 psi
Air Pressure