The Wind Hold for Ladders, Roofs and Spraying SOP

Purpose

Wind injures people at height in one move: a gust catches a sheet, a panel or a platform and takes the person holding it with it. It also ruins work at ground level, by carrying spray onto a neighbor's car, a garden or a person. This procedure gives the shop one table of wind limits by task, each with its sustained and gust figure and the source that sets it, names who measures on site and how, makes a gust measured on site outrank any forecast, and says what the crew stops, how they resume, and what work moves inside. Without it, every lead sets their own limit by feel, and the limit drifts upward on the days the schedule is tight.

Scope

Covers aerial lift work, ladder work with and without sheet goods, walking a roof and tarping, handling panels and sheets on a roof, and outdoor spraying of pesticides, paints and coatings.

Does not cover how wind acts on a lift (see related: What Wind Does to a Lift and When It Stops It), on a person and a sheet on a ladder (see related: Wind on a Ladder and the Sheet You Carry Up It), or on spray (see related: Spraying in Wind: Drift, Overspray and the Calm-Day Trap). Lightning has its own stop rule (see related: The Lightning Stop Work SOP), and storm preparation its own procedure (see related: How to Secure a Job Site Days Before a Forecast Storm). The forecast-day call is made under 'The Daily Weather Go/No-Go SOP', using this table.

Roles and responsibilities

The shop wind table

SHOP WIND LIMITS   mph at working height   rev. Mar
TASK                    SUSTAINED  GUST    SOURCE
Aerial lift             rating     rating  unit decal
Ladder, no load         20         25      shop
Ladder carrying a sheet 15         20      shop
  (any sheet or panel over 8 sq ft)
Roof walking, tarping   20         30      shop
Roof panel handling     15         20      shop
Spray, pesticide        label      label   label
  label silent          2 to 10    15      shop
Spray, paint, coating   10         15      shop
STOP AT WHICHEVER COLUMN IS REACHED FIRST

"Shop" rows are this shop's defaults, set conservatively; tune them, but only downward on the day. The lift row is the rating printed on that unit's decal and in its manual, commonly 28 mph (12.5 m/s) on units rated for outdoor use under the ANSI/SAIA A92 standards and zero on units rated for indoor use only, and the manual says whether the rating includes gusts; where it does not say, this shop reads it as a gust limit. A pesticide label's wind directions are part of the label, and applying outside them is use inconsistent with the labeling under FIFRA and state pesticide law. The 2 mph floor on a silent label is there because near-calm air on a clear morning can mean a temperature inversion that carries fine droplets a long way.

Procedure

1. Keep the table current and read each lift into it. The shop manager reviews the table at the start of each season and whenever a new lift, rented or owned, comes onto a job: the rated wind speed is read off that unit's decal and manual and written on the job, because two lifts on the same site can carry different ratings. Acceptance: a dated table posted in every truck, and every lift on the board with its own rating on the job. Wrong looks like a rented lift with no rating recorded; the stop rule is it does not go up until the lead reads the decal. Hazard: reading a decal is ground work; the lift's platform is not raised to find the manual.

2. Compare the forecast against the table at the afternoon read and morning recheck. The dispatcher writes the peak sustained wind and peak gust during the task's hours against the task's row. A forecast is usually issued for about 33 ft (10 m) above open ground; wind at a roof edge, a gable or a platform above the treeline is often stronger, and gusts channel between buildings, so a forecast near the limit is a site check, never a go. Acceptance: a go only where the forecast peak gust is at least 5 mph under the row's gust figure and the peak sustained wind at least 5 mph under its sustained figure. Wrong looks like a go issued on average wind alone; the stop rule is the dispatcher rewrites it as a site check. Hazard: none at the desk.

3. Before the task starts, the lead takes a site reading at working height. With a handheld anemometer, the lead reads for 2 minutes: the average across the 2 minutes is the sustained figure, the highest reading is the gust. The first reading is at the ground; where the task is at height, a second is taken as close to working height as the lead can reach without breaking a row of the table, for example from an unloaded ladder at the eave, or from the lift platform at a low height. Acceptance: both figures under the task's row, recorded with time and height. Wrong looks like a ground reading used for work at the eave; the stop rule is no task at height starts on a ground reading alone. Hazard: the reading at height is itself ladder or lift work and is taken only when the ground reading is under the no-load or lift row.

4. A site gust over the limit stops the task, whatever the forecast says. During the task, the lead re-reads every 30 minutes and any time the wind changes in sound or feel; any crew member may call a stop on a gust they feel. A stop is immediate and the reason is recorded later. Acceptance: readings every 30 minutes on the record, each under the row. Wrong looks like "it's only gusting, the forecast said 12"; that is the stop rule's reason to exist, and the task stops. Hazard: the moment of a stop is the moment of highest exposure; the stop sequence in step 5 is followed, never "one more sheet."

5. Stop in the order that removes the sail first. On a ladder, the sheet comes down or is set flat on the ground with weight on it before anyone climbs again. On a roof, loose panels and sheets are laid flat and secured or brought down, and the crew comes off by the ladder with three points of contact and nothing in their hands. On a lift, the platform is lowered and stowed per its manual, with the boom out of the wind's line where possible, and occupants stay tied off until it is stowed. Spraying stops, the gun is locked and the nozzle capped. Acceptance: nothing loose at height, nobody at height, a stop recorded with the reading. Wrong looks like a crew member at the eave holding a panel against a gust; the stop rule is let go of the panel before you let go of the ladder. Hazard: as stated in each sequence; a sheet released at height is a falling object, so the ground below it is kept clear while the stop is carried out.

6. Resume only after 15 continuous minutes under the limit. The lead takes readings at working height throughout a 15-minute period; every gust in that period must stay under the row. The dispatcher is told before work restarts. Acceptance: a 15-minute series recorded, all under the row. Wrong looks like resuming in a lull between gusts; the stop rule is one gust over the limit restarts the 15 minutes. Hazard: resuming is the step where people go back to height carrying the thing the wind caught; the first lift of a sheet after a resume is a two-person carry, low and edge-on to the wind, and the crew keeps the ground below the work clear.

7. Move the crew to work the wind does not govern. On a stop, the lead calls the dispatcher and the crew moves to work with no wind exposure: interior items on the same job, cutting and prepping panels at ground level in the lee of the building, a south elevation sheltered from a north wind if its reading passes, shop work, or an indoor job from backlog. Acceptance: the crew is working within 30 minutes of the stop, on a task the reading allows. Wrong looks like a crew sitting in the truck waiting for the wind to drop; the stop rule is the dispatcher reassigns them. Hazard: ground-level cutting in wind follows the same eye protection and dust control as any cut, and offcuts are weighted before they become missiles.

8. Record every reading, stop and resume. Acceptance: the job carries the forecast values, each site reading with time and height, each stop, the 15-minute resume series, and the work the crew moved to. Wrong looks like a stop and resume with no readings between them; the stop rule is the lead fills the series from the anemometer's memory or notes before leaving. Hazard: none, desk work.

The record this produces

On the job: the task's table row, the forecast sustained and gust at the afternoon read and morning recheck, the lift rating where one is used, each site reading with time, height and the two figures, every stop with the reading that caused it, the resume series, and the reassigned work. The manager reads stops by task each month to see whether a row is set wrong; the owner reads the record after any wind incident, because it shows whether the crew was inside the table when it happened.

A worked pass

A two-person crew replaces vented soffit panels on a two-story house. The panels are 16 in by 12 ft, which is 1.33 ft times 12 ft, about 16 sq ft each, so the "ladder carrying a sheet" row applies: 15 mph sustained, 20 mph gust. The soffit is about 20 ft up.

Step 2. Morning recheck forecast: peak sustained 8 mph, peak gust 14 mph at 13:00. Against the row, 20 minus 14 is 6 mph of gust margin and 15 minus 8 is 7 mph of sustained margin, both at least 5, a go.

Step 3. At 10:15 the lead reads 2 minutes at the ground: sustained 7, gust 13. Under the no-load row of 20 and 25, so the lead climbs the unloaded ladder to the eave for the second reading: sustained 11, gust 24. The gust of 24 is over the sheet row's 20. Step 3 fails, and no sheet goes up; the eave reading is 11 mph higher than the ground gust because the wind wraps the corner of the house at that height. The 24 is also within 1 mph of the no-load row's 25, so the lead comes down.

Step 7. The crew moves to cutting and prepping all panels to length at ground level on the lee side of the garage, and to replacing two rotted fascia boards at the single-story porch, where the eave reading at 10:40 was sustained 6, gust 12, inside the "ladder carrying a sheet" row; the boards are under 8 sq ft, so the no-load row would also have covered them.

Step 6. Starting at 13:20, the lead reads at the two-story eave from the unloaded ladder. At 13:26 a gust of 21 restarts the clock. From 13:30 to 13:45 the series reads sustained 9 to 12 and gusts 15 to 19, all under 20. The lead phones the dispatcher at 13:46, and the first panel goes up at 13:50 with two people.

Step 4. Re-reads at 14:20 (sustained 10, gust 18) and 14:50 (sustained 9, gust 16) stay under the row, and the panels are finished at 15:30. The record shows a morning go on the forecast, a site fail at the eave, the reassigned work, the restarted resume clock and both later reads, which is exactly the day the forecast alone would have gotten wrong.

References

• The aerial lift's manufacturer manual and decal, and ANSI/SAIA A92 standards as adopted by contract or your jurisdiction
• The pesticide product label, enforceable under FIFRA and state pesticide law
• See related: Sustained Wind Versus Gusts and Which One a Limit Means
• See related: What Wind Does to a Lift and When It Stops It
• See related: Wind on a Ladder and the Sheet You Carry Up It