Rebar mats: the walk across the mat that moves

A #5 bar on 12-inch centers is a floor made of one-inch rungs with 11-inch holes between them. You walk it all day, and every step is a choice of where the boot lands.

The points

• The rodbuster's injuries are the ankle that goes down between the bars, the knee that lands on a bar, and the one that kills: a trip that ends on a vertical dowel. A fall from standing onto uncapped rebar is an impalement, and the rule says every bar you could fall onto is guarded.
• Walk the bars, not the gaps: boot on the bar, across the intersections where two bars are tied, never on a bar that is only sitting on a chair. Carry nothing that stops you seeing where the next foot goes.
• A top mat on standees that are not tied is a mat that shifts under your weight. Tie the standees and the corners first, then fill in, so the mat you are walking on is the mat that is fixed.
• Tie wire ends stick up exactly at eye height when you bend over the next tie. Bend the ends down into the mat as you go, and safety glasses stay on, every tie, all day.
• Vertical bars, dowels and column starters get an impalement-rated cap or a trough the moment they are placed. The plastic mushroom cap keeps the rain out, it does not stop a body.

Why it goes wrong

Impalement is not a rare accident in this trade. A fall from standing height onto a #5 dowel drives the bar in with the full weight of the body behind it, and the wound is a bar the crew cannot pull out. The rule in 1926.701 is one line: every protruding bar that a person could fall onto or into is guarded. That includes the dowels along the edge of the mat you are walking, the wall starters, and the bars sticking out of the footing next to the ladder.

Caps: the orange mushroom cap is a rain cap and a visibility cap. An impalement-protective cap has a steel plate or a wide footprint designed and tested to spread the load of a falling worker across the top of the bar. Troughs, wood boards over a row of dowels, and bending the bar over are all acceptable when the cap is not. Bar by bar, one cap each, before the next bar is set.

The mat shifts because the bottom mat sits on chairs and the top mat sits on standees or bolsters, and until the mat is tied at the corners and along the standees, the whole top layer can slide sideways as a unit. A rodbuster stepping onto the untied end of a top mat rides it two inches and goes down between the bars. Tie the frame of the mat before anyone walks the middle.

Feet: a boot between #5 bars at 12 inches goes down to the bottom mat, 6 to 8 inches, and the ankle folds against the top bar. Walking on the intersections means the load is on a tied crossing, not a bar that rolls. On a slab with bars at 6 inches, walk the bar lines and slow down. Runways of planks over the mat are cheaper than the ankle.

Tie wire cuts and eye injuries: the tail of a tie is a wire spring at face height. Reel ties and pliers leave sharp ends, and a bent-over rodbuster puts the eye a foot from the last tail. Bend or turn the tails into the mat as you go. Glasses stay on even when they fog, because the tail does not wait for the fog to clear.

Carrying bar across the mat: a 20-foot #8 is 53 pounds and a 20-foot #11 is 106. Two people, same shoulder, called out before they lift, and the walk is along a bar line, not across it. Do not throw bar across the mat to save a trip. It bounces, and the person it bounces toward is standing on rungs.

Questions for the crew

1. Which bars on this pour could someone fall onto right now, and what is on the top of each one?
2. Is the top mat tied at the corners and the standees before we start walking the middle?
3. Where are the bar bundles landing, and what is the path from there across the mat?

To close

Today every vertical bar gets its cap before the next bar is set, and nobody walks the mat until the frame of it is tied.