Drainage Reference · Load Ratings A–F

Load Class Recommendation Guide

Q: What is the difference between load class and PSI?

Load class is a category (A to F) that bundles a tested weight capacity, application type, and material recommendation. PSI is one of the underlying pressure measurements used to define each class.

Every trench drain and grate is rated for the traffic it can carry. Use this guide to match a load class to your site — from pedestrian walkways to airport aprons — by pressure (PSI), weight capacity, material, and application.

Quick Comparison — All Load Classes
Class	Duty Level	Load (PSI)	Capacity (kN)	Capacity (lbs/ft)	Typical Use
A	Light Duty	1–60	15	3,372	Sidewalks, parks
B	Medium Duty	61–175	125	28,100	Driveways, parking lots
C	Heavy Duty	176–325	250	56,200	Warehouses · H-20
D	Extra Heavy Duty	326–575	400	89,920	Airports, freight · H-20
E	Very Extreme Heavy Duty	10,000–15,000	600	134,900	Ports, rail yards
F	Maximum Load	15,000+	900	202,000+	Runways, military

Class A

Light Duty Traffic

15 kN capacity

Class A light-duty pedestrian traffic drainage grate

Load

1–60 PSI

Capacity

15 kN

Weight / ft

3,372 lbs

Material

HDPE → Steel

Features

Recommended for pedestrians, bicycles, and wheelchair traffic only
Materials range from High-Density Polyethylene to Steel

Applications

Sidewalks and walkways
Recreational areas and parks

Class B

Medium Duty Traffic

125 kN capacity

Class B medium-duty vehicle traffic drainage grate

Load

61–175 PSI

Capacity

125 kN

Weight / ft

28,100 lbs

Material

HDPE → Steel

Features

For medium-duty tire traffic, automobiles, and light trucks at speeds under 20 mph
Materials range from High-Density Polyethylene to Steel

Applications

Sidewalks and walkways
Recreational areas and parks
Garages and parking lots

Class C

Heavy Duty Traffic

250 kN capacity

Class C heavy-duty forklift and truck traffic drainage grate

Load

176–325 PSI

Capacity

250 kN

Weight / ft

56,200 lbs

Material

HDPE → Iron

Features

For heavy-duty pneumatic-tire forklifts and tractor trailers at speeds under 20 mph H-20 RATED
Materials range from High-Density Polyethylene to Iron

Applications

Warehouses
Industrial facilities and distribution centers
Garages and parking lots
Construction sites

Class D

Extra Heavy Duty Traffic

400 kN capacity

Load

326–575 PSI

Capacity

400 kN

Weight / ft

89,920 lbs

Material

Steel → Iron

Features

For extra heavy-duty hard-tire forklifts at speeds under 20 mph H-20 RATED
Materials range from Steel to Iron

Applications

Warehouses
Industrial facilities and distribution centers
Garages and parking lots
Construction sites
Airports and airfields
Military installations
Freight terminals

Class E

Very Extreme Heavy Duty

600 kN capacity

Load

10,000–15,000 PSI

Capacity

600 kN

Weight / ft

134,900 lbs

Material

Steel → Iron

Features

For ports, container terminals, heavy industrial facilities, and extreme vehicular loads under 20 mph
Materials range from Steel to Iron

Applications

Port facilities and shipping terminals
Container yards and intermodal facilities
Heavy manufacturing and industrial plants
Mining operations and heavy equipment areas
Rail yards and freight transfer stations

Class F

Maximum Load

900 kN capacity

Load

15,000+ PSI

Capacity

900 kN

Weight / ft

202,000+ lbs

Material

Steel → Iron

Features

For aircraft facilities, military installations, specialized port infrastructure, and maximum vehicular loads under 20 mph
Materials range from Steel to Iron

Applications

Airport runways, taxiways, and aprons
Military airfields and vehicle testing facilities
Specialized port and cargo handling areas
Heavy industrial sites with extreme equipment loads
Critical infrastructure requiring maximum load capacity

Frequently Asked Questions

What does "H-20 rated" mean for a drainage grate?

H-20 is an AASHTO highway loading standard representing a 16,000 lb wheel load. Load Classes C and D meet H-20, making them suitable for trucks, forklifts, and tractor trailers.

Which load class do I need for a residential driveway?

Class B (Medium Duty) is typically sufficient for residential driveways and light vehicle traffic. Class A is for pedestrian-only areas, while Class C and above handle commercial and industrial vehicle loads.

What is the difference between load class and PSI?

Load class is a category (A–F) that bundles a tested weight capacity, application type, and material recommendation. PSI is one of the underlying pressure measurements used to define each class.

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