How to Replace 1 Inch Thick Grates

1 in Thick Bar Grate

Let’s just say it: 1” thick grates aren’t considered heavy duty anymore.

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This 1 in. cast iron grate had seen better days before the owner called to replace them.

Standards change. Architects once specified one inch thick iron grates for loading docks, warehouses and industrial areas. Typically, contractors installed them in an angle iron frame using the old wooden box form method.

Why can’t I replace my 1” iron grates?

  • Increased traffic loads
  • Industry shift to modular systems
  • Market standardization

Expected loads increased, and the 1 in. thick grate became rare, a holdover from decades past. New construction projects specify newer, standard sizes such as the ¾” thick grate with a strengthening frame. Foundries offer 1-1/2” and thicker grates almost exclusively – no extra reinforcement needed.

How do I replace 1” thick grates?



Replace with FiberglassFiberglass Bar Grating

Already a popular replacement choice, fiberglass grates have several things going for them.

  • Chemical/rust resistant
  • Load bearing capability
  • Low scrap value

Fiberglass grates are durable, rust-proof and not stolen for the scrap value. They come in several patterns and load classes, so ask an expert before replacing anything. However, in the right circumstances a 1 inch fiberglass grate will make a suitable replacement for aged cast iron.


Replace with Foundry Grates

Most foundries moved to supplying 1-1/2” thick grates, but Trench Drain Systems knows a couple holdouts. The grates are no longer officially traffic rated, which means if they do break the foundry is not liable. The standard grate thickness changed for a reason, after all.

POLYCAST with SS GrateReplace with Steel Bar Grates

Steel bar grates might be the exception to the rule. You can find 1” thick bar grates pretty easily in custom widths, lengths and styles. Wider grates require more bearing bars to keep the same level of strength as narrower varieties, so be careful to account for the traffic crossing over your drain when deciding. If in doubt, ask an expert.


Install a Modern Drainage System

This is the least popular option, but it’s the one I recommend most. I don’t prefer it for any monetary benefit; sometimes this is the option that makes the most sense.

When to just reinstall the drain:

ZURN Trench Drain

  • Fiberglass or bar grating won’t be strong enough
  • Foundry grates don’t come in that width
  • The channel or surrounding concrete shows damage

If any or all of these criteria are met, you’re better off reinstalling the drain with a modern system that meets new construction expectations. When starting with a 12” wide (or larger) trench drain, you might not even have to cut out the old system!

Questions about replacing old, broken grates? Give the experts at Trench Drain Systems a call 610-638-1221 and find out your options! Shop online at

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