19W4 Steel Grating Specification: Bar Sizes, Weights and Span Guide

GNEE STEEL 19W4 steel grating is a welded bar grating with bearing bars at 19/16 in (30.2 mm) on centre and twisted cross bars at 4 in (101.6 mm) on centre, hot-dip galvanized after fabrication. This page gives the numbers specifiers ask for most: bar sizes, weight, open area, stiffness and span.

1. What "19W4" Tells You — and What It Does Not

Written properly as 19-W-4 per ANSI/NAAMM MBG 531:

· 19 — bearing bar spacing in sixteenths of an inch. 19/16 in = 1-3/16 in (30.16 mm) centre to centre.

· W — welded construction. Alternatives are P press-locked, S swage-locked and R riveted.

· 4 — cross bar spacing, 4 in (101.6 mm) centre to centre.

Two cautions. Some catalogues gloss the first number as "1-3/4 inch spacing"; it is 1-3/16 inch. And the code says nothing about bar size, surface or finish, so two gratings both called 19W4 can differ in capacity several times over.

The nearest metric grating is 30 mm bearing bar pitch by 100 mm cross bar pitch under YB/T 4001.1. The pitch differs by about half a millimetre. Most projects treat the two as interchangeable, but drawings should say which one you mean.

2. Construction: Bars, Cross Bars and Welds

The cross bar step is not decoration: deeper bars push more shear through each welded node.

3. Weight per Square Foot

Published weights are nominal and exclude zinc. Allow roughly 5% more for galvanized panels when planning shipping weights.

A 3 ft by 24 ft panel is the common full-sheet size. Anything above roughly 250 kg needs mechanical handling on site.

4. Open Area

Open area follows straight from the geometry:

% open = (1 − bar thickness ÷ 1.1875) × (1 − cross bar size ÷ 4) × 100

For 19W4 that gives about 84% with a 1/8 in bar, 79% with 3/16 in and 74% with 1/4 in. With the same 3/16 in bar across the common meshes: 19-W-4 gives 79%, 15-W-4 about 75%, and 11-W-4 about 68%.

High open area means fast drainage, daylight through the deck and sprinkler water reaching the level below. It also means a 1-3/16 in slot drops small parts and is not heel-proof.

5. Stiffness and Span

There are 10.1 bearing bars in every foot of width, so section modulus per foot of width is close to:

Z ≈ 1.68 × bar thickness × bar depth² (in³/ft)

These are conservative planning figures at L/200 deflection for pedestrian and light equipment loads. They are not a load table. Send your span and we will return the calculated capacity for your bar size.

One comparison worth knowing: with the same bar size, 11-W-4 carries about 70% more section modulus per foot of width than 19W4, since it packs more bars in. It also weighs more and drains less.

6. Materials, Finish and Standards

Base steel is Q235B, ASTM A36 or S275JR; stainless 304 and 316 for washdown and food areas. Hot-dip galvanizing to ASTM A123 / ISO 1461, after fabrication. We also work to ANSI/NAAMM MBG 531, BS 4592 and YB/T 4001.1. Panels are cut after welding, so state the dimensional tolerance you need in the order.

7. FAQ

Is 19W4 the same as 30/100 grating? Near enough on spacing, but they are separate specifications. State one.

Can it take forklift traffic? Yes with a deep bar, once wheel loads are checked. See our page on heavy duty galvanized grating.

Serrated or plain? Serrated for wet or oily decks. The teeth cut away metal, so allow about 1/4 in more bar depth for equal capacity.