Suspended scaffolds, weather, falling objects and capstone: a façade repair plan

This final lesson rounds out the course. It introduces suspended scaffolds at an awareness level, covers weather and falling object protection for all scaffolds and ladders, and then brings everything together in a capstone plan for repairing the façade of a three-story building next to a public sidewalk.

Suspended scaffolds at an awareness level

Suspended scaffolds hang from the roof or structure on wire ropes. They include two-point adjustable suspension scaffolds, usually called swing stages, multi-point suspended platforms, single-point systems and boatswain's chairs. They are used for window cleaning, façade repair, painting and glazing on tall buildings where a supported scaffold would be impractical.

Suspended scaffolds have hazards of their own:

• the roof rigging, outriggers, parapet clamps or davits must hold the load with a large margin, and counterweights must be secured and made of solid material, not sand or water;
• the suspension ropes and hoists must be inspected and rated for the load;
• the platform can tilt if one end is raised faster than the other, or fall if a rope, hoist or anchor fails;
• the work is close to the building edge at great height, often in wind.

Because of these hazards, OSHA's Subpart L has specific rules for suspension scaffolds. Suspension ropes and connecting hardware must support at least 6 times the maximum intended load (1926.451(a)(4)). Counterweights must be made of non-flowable material and secured against displacement, and outrigger beams must be tied back to a structurally sound anchorage (1926.451(d)). Each employee on a single-point or two-point adjustable suspension scaffold must be protected by both a personal fall arrest system and a guardrail system (1926.451(g)(1)(ii)), with lifelines independent of the scaffold. Only trained workers may rig and operate the equipment.

Suspended scaffold failures are rare but often fatal, because the fall height is large and several workers may be on one platform. Investigations repeatedly find the same causes: overloading, improper rigging or counterweights, damaged ropes, and workers not connected to independent lifelines. Following the Subpart L rules every time, with a competent person checking the rigging, prevents these deaths.

Weather

Weather affects every ladder and scaffold job.

• Wind: OSHA prohibits work on scaffolds during storms or high winds unless a competent person determines that it is safe and workers are protected by personal fall arrest or wind screens (1926.451(f)(12)). Wind screens require the scaffold to be designed and tied for the extra load.
• Ice and snow: work on scaffolds covered with snow, ice or other slippery material is prohibited except to remove it (1926.451(f)(8)). Watch for ice falling from roofs.
• Rain: wet planks and rungs are slippery; heavy rain softens ground under sills and washes out footings.
• Lightning: stop work on metal scaffolds and ladders and get to shelter. A common rule is to wait 30 minutes after the last thunder before resuming.
• Heat and cold: plan breaks, water and shade in heat, and warm clothing and gloves that still allow a good grip in cold. Cold aluminum and steel can sap hand strength quickly.
• Freeze and thaw: frozen ground that thaws can let sills sink; inspect foundations after thaws.

Falling objects and public protection

Tools, materials and debris falling from ladders and scaffolds injure workers below and members of the public. Protection uses the hierarchy again:

• Keep materials secured and away from platform edges; stack neatly within the rated load.
• Use toe boards, screens, mesh or debris netting on guardrails.
• Tether tools at height and use bags or buckets on lines to raise materials.
• Barricade the area below, mark it with signs and keep people out of the drop zone.
• Build covered walkways or hoarding over sidewalks and entrances.
• Require hard hats for everyone in the area.

OSHA's 1926.451(h) requires hard hats and additional protection where tools, materials or equipment could fall on people below: barricades, toe boards, screens, guardrail systems, debris nets, catch platforms or canopies. Work beside a public sidewalk or street usually needs a local encroachment permit, a covered walkway and traffic control.

Capstone: a ladder and scaffold plan for a façade repair

A property manager hires your company to repair loose brick and replace sealant around windows on the street façade of a three-story commercial building. The façade is 80 ft long and the parapet is 36 ft above the sidewalk. The sidewalk is 10 ft wide and busy. There is an overhead electrical service drop at one end of the building. The work will take four weeks in late autumn. Prepare a plan.

Step 1: choose the means of access

The work is long, involves materials (brick, mortar, sealant) and needs both hands for hours at a time. A ladder is not suitable except for the initial survey and for short tasks. Options are a frame or system scaffold along the façade, a mast climbing work platform, or a suspended platform from the roof. With a parapet only 11 m high, a busy sidewalk and four weeks of work, a frame or system scaffold with a covered walkway is a practical choice.

Step 2: plan the scaffold

• Height: about 36 ft to the top working level. A qualified person designs it; at this height a professional engineer is not required by Subpart L for frame scaffolds, but the covered walkway, debris netting and sidewalk loads make an engineered design prudent, and the city may require one for the permit.
• Duty class: masonry with stockpiled brick means a heavy-duty platform, 75 lb per square foot.
• Foundation: the sidewalk is concrete; use base plates on timber sills to protect the surface and spread loads, with screw jacks to level across the sidewalk's cross-slope.
• Ties: the scaffold is about 5 ft wide. The lowest tie at no more than 20 ft, the next within 26 ft above it, and ties at each end and every 30 ft horizontally. The qualified person will add ties because of the debris netting.
• Access: a stair tower at the end away from the power line, so crews can carry tools safely.
• Guardrails with a 38 to 45 in top rail, midrails and toe boards on all open sides and ends; the platform front edge within 14 in of the wall or guarded.

Step 3: public protection

• Apply for the municipal sidewalk permit.
• Build a covered pedestrian walkway under the scaffold with solid decking, lighting and side screens, or divert pedestrians across the street with signs if the city requires it.
• Debris netting on the scaffold face, toe boards and tool tethers.
• Barricades at both ends with signs; keep the building entrances open under protected canopies.

Step 4: electrical hazard

The overhead service drop at one end carries low voltage, but contact can still kill. Under 1926.451(f)(6), scaffolds must keep at least 3 ft from insulated lines under 300 volts, and at least 10 ft from uninsulated lines up to 50 kV, unless the utility de-energizes, relocates or covers the line. Ask the utility to cover or de-energize the drop, and use nonconductive ladders for the survey.

Step 5: people, inspection and tags

• Name the competent person who will erect and inspect the scaffold, and the trained crew.
• Red tag the scaffold during erection; green tag after the first inspection and written confirmation.
• Inspect before each shift, and after wind, rain, frost or any impact.
• Train masons and sealant workers as scaffold users: loads, tags, no alterations, ladder and stair use, weather rules.

Step 6: weather and season

Late autumn brings wind, rain and early frost. Set a wind stop rule, keep salt or sand for icy mornings, inspect sills after thaws, and plan for shorter daylight with temporary lighting on the walkway and stairs.

Step 7: dismantling

Plan the dismantling sequence: remove debris and materials, keep the walkway in place until the scaffold above is gone, remove ties only as each lift comes down, lower components with a gin wheel or hoist and keep the sidewalk barricaded throughout.

Reviewing the plan

A good plan is reviewed before work starts and again whenever conditions change. Walk the site with the scaffold contractor, the masonry crew lead and the property manager. Confirm the permit, the walkway design, the utility arrangement for the service drop, the tie points on the façade and the emergency procedure, including how an injured worker would be brought down from the scaffold. Post the plan, the emergency contacts and the competent person's name at the access point. After the first week, review how the plan is working and adjust: perhaps the wind rule needs refining, or deliveries need a better landing area.

The plan is only useful if the people doing the work know it. Brief every worker on the access route, the tags, the load limits, the no-alteration rule, the weather stop rules and what to do if they see a defect. Encourage them to stop and ask if anything does not match the plan.

At the end of the job, hold a short review: what went well, what nearly went wrong and what the next façade project should do differently.

Every element in the plan connects back to the earlier lessons: the access choice from lesson 1, the rules from lesson 2, ladder selection and set-up from lessons 3 to 7, and the scaffold design, stability and inspection from lessons 8 to 11.