Renovation projects and occupied buildings

At 6:40 on a Tuesday morning, Gareth Lowe, superintendent for Harborline Construction Inc., walked the third floor of the East Wing at Ashgrove Health Center with a coffee in one hand and a set of 1974 drawings in the other. The corridor smelled of floor wax. Two doors down, the hospital's medical records staff were already at their desks, and in six weeks they would be working on the far side of a plywood wall while Harborline gutted the space behind them. Below him, on level 1, a temporary outpatient clinic was running in rooms the hospital had borrowed from the Main Building. None of this would happen on a greenfield site. On a new building the contractor owns the site. On a renovation in an occupied building, the contractor is a guest in someone else's home, and every decision about noise, dust, access, shutdowns and safety has to work for the people who live there.

This course follows one project from first walk-through to the end of the warranty year. Ashgrove Health is renovating the three-story East Wing of its hospital campus in Minneapolis, Minnesota: about 45,000 ft² of floor area built in 1974, to be turned into an ambulatory care clinic on level 1, a dialysis unit on level 2 and education and office space on level 3. The work includes a new rooftop air handling unit, new heating and cooling distribution, a new fire alarm system connected to the hospital's existing network, sprinklers throughout and a staff childcare room on level 1. The contract, a stipulated price contract of about $15.4 million, names Harborline as the general contractor, Pell & Strand Architects as the Architect, Coldwater Engineering as mechanical and electrical engineer and Kestrel Commissioning Group as the owner's commissioning authority.

The Main Building next door stays open twenty-four hours a day throughout. It holds the emergency department, inpatient units and the operating rooms. Several of its systems run through the East Wing: a steam line, the main fire alarm loop, medical gas risers and a data backbone. That single fact shapes most of the plan. Every shutdown of a shared system has to be negotiated, scheduled and rehearsed; every penetration in a wall that separates the work from patient areas has to be sealed; and every day ends with the site left safe for a building that never sleeps.

What makes renovation different

Renovation covers a wide range of work, from a simple fit-out of an empty floor to a full gut and rebuild of an old structure. The words used vary by region and by company, but the main types are worth knowing because they carry different risks.

Whatever the label, renovation differs from new construction in five ways that a project team must plan for from the first day.

• Unknowns. The existing building is never exactly as the drawings show. Walls hide old services, slabs hide conduits and post-tensioning, ceilings hide asbestos, and past renovations were often poorly recorded.
• Occupants. People keep living, working or receiving care in or next to the work. Their health, safety and comfort set limits on noise, vibration, dust, odors, hours and access.
• Tie-ins and shutdowns. New systems must connect to old ones that are still in service. Every connection risks interrupting power, water, heat, air or fire protection to occupied areas.
• Tight logistics. There is rarely a laydown yard. Material moves through shared loading docks, elevators and corridors, often at night.
• Code triggers. Changing a space can require upgrades elsewhere: fire separations, exits, accessibility, energy performance. The scope can grow if these are missed early.

The people around the work

On a greenfield site, the contractor's main relationship is with the owner's project manager and the Architect. In an occupied building the list of people with a stake in daily decisions is much longer. On Ashgrove, Simone Dufresne, Harborline's project manager, drew a stakeholder map in the first week and kept it on the wall of the site office.

The most important person on that list was not on the contract at all. Dr. Moreau, the hospital's infection prevention and control manager, could stop the work if a dust barrier failed near an immunocompromised patient. Harborline treated her as a decision maker with real authority, invited her to the preconstruction meetings, and built her inspections into the daily routine instead of waiting for her to find problems. Lesson 2 covers infection control in detail.

Phasing: doing the work in pieces

Phasing is the division of a renovation into stages so that parts of the building stay in use while others are rebuilt. A phasing plan shows which areas are under construction, which are occupied, which are temporary and how people move between them at each stage. It is drawn early, agreed with the owner, and becomes part of the contract documents on most renovation projects.

The Ashgrove plan had four phases. In phase 1, Harborline built the new rooftop mechanical room and replaced the main risers while every floor stayed in use, working mostly at night inside shafts and on the roof. In phase 2, level 2 was gutted and rebuilt as the dialysis unit, with level 3 staff still at work above and the temporary clinic still below. In phase 3, the dialysis unit opened, level 3 staff moved temporarily into part of it for twelve weeks, and level 3 and level 1 were rebuilt together. In phase 4, level 3 staff moved back, the clinic and childcare room opened, and the last temporary walls came down.

Each phase change is a small project of its own. Before people move into a newly finished area, it has to be inspected, commissioned and accepted, and the authorities may need to allow partial occupancy. Before construction starts in a newly vacated area, the hospital's equipment has to be moved, services isolated and barriers built. Simone's schedule showed every phase change as a milestone with its own checklist, because a missed item at a phase change could leave staff working in an area with no heat or a fire alarm that did not report to the switchboard.

Shutdowns and tie-ins

A shutdown is a planned interruption of a building system so that new work can be connected or old work removed. In a hospital, a shutdown of power, medical gases, water, heating, ventilation or fire protection can directly affect patients, so it is planned in detail and approved in writing. Many owners use a form called a method of procedure, or MOP, which sets out each step, who does it, how long it takes and how the system will be restored if something goes wrong.

• Scope: which system is affected, which areas lose service, and for how long.
• Timing: the approved window, usually at night or on a weekend, with a hard end time.
• Preparation: materials on site, prefabricated pieces, tools tested, temporary services in place.
• Steps: a numbered sequence from isolation through connection, testing and restoration.
• Roles: who isolates, who works, who tests, who confirms restoration, and who the owner's contact is.
• Back-out plan: the point at which the team stops and restores service if the work is running late.

On Ashgrove, connecting the new heating water piping to the hospital's existing loop needed a six-hour shutdown of heating to the East Wing and part of the Main Building. Harborline prefabricated the connections, did a dry run with the pipefitters a week before, and scheduled the work for a Sunday in late April, when outdoor temperatures were mild. Helen's staff monitored room temperatures in the affected inpatient unit every hour. The work finished in four hours and forty minutes, with time to spare.

Working hours, noise and vibration

Noise and vibration are the complaints that occupied-building projects hear most. Coring through concrete, chipping floors, demolishing masonry and drilling anchors are all loud, and the noise travels through the structure to floors far from the work. Most owners set rules for when noisy work may happen. Ashgrove's rules allowed noisy work on weekdays only between 7:00 and 9:00 in the morning and between 17:00 and 21:00 in the evening, with no noisy work near the dialysis unit during treatment sessions once it opened.

Restrictions like these lengthen the schedule and raise the cost. Crews work in short bursts, set up and clean up more often, and sometimes need premium time. Experienced estimators price the restrictions into the bid by applying a productivity factor to the affected work, and experienced project managers schedule quiet work, such as framing or electrical rough-in, in between the noisy windows so that crews stay busy.

Simone used a short program to test different window rules before agreeing them with the hospital. It showed that adding a single extra hour in the evening shortened the noisy work by three days.

# Effect of restricted noisy-work windows on duration and crew-hours
import math

base_hours = 320       # productive crew-hours needed
crew = 4
for window in (4, 5, 6, 7, 8):
    eff = 0.85 if window < 8 else 1.0
    per_day = crew * window * eff
    days = math.ceil(base_hours / per_day)
    paid = crew * window * days
    print(f'{window} h window: {days:2d} days, {paid} paid crew-hours, {paid - base_hours:+d} extra')

4 h window: 24 days, 384 paid crew-hours, +64 extra
5 h window: 19 days, 380 paid crew-hours, +60 extra
6 h window: 16 days, 384 paid crew-hours, +64 extra
7 h window: 14 days, 392 paid crew-hours, +72 extra
8 h window: 10 days, 320 paid crew-hours, +0 extra

Keeping the building safe while it is torn apart

In an occupied building, the contractor's work can weaken the protections that keep occupants safe. Demolition opens fire separations. Sprinkler and fire alarm work takes protection out of service. Temporary walls can block exits. Hot work can start fires in hidden spaces. A renovation safety plan addresses each of these risks, often under the owner's own rules and the requirements of the fire code.

• Fire protection impairments: when a sprinkler zone or fire alarm device is out of service, the owner and fire department are told, a fire watch patrols the area, and the system is restored at the end of each shift where possible.
• Exits: every occupied area keeps at least the required exits, with temporary signs and lighting where routes change.
• Fire separations: openings made during the day are closed or protected before the crew leaves.
• Hot work: permits, a fire watch during the work and for a period afterwards, and removal of combustibles.
• Housekeeping: debris is removed daily, and combustible waste is never stored in corridors.

Gareth's end-of-shift checklist on Ashgrove had fourteen items, from 'all temporary barriers intact and sealed' to 'fire alarm devices restored and confirmed with the switchboard'. A foreman signed it every night, and the security guard on duty initialed it. Twice in the first month the checklist caught a sprinkler valve left closed after a day's work.

Communication with occupants

People tolerate a great deal of disruption if they know what is coming, why, and for how long. They become angry when work surprises them. The communication plan for an occupied-building project is therefore a working tool, not a courtesy. On Ashgrove it included a two-week look-ahead of disruptive work sent to unit managers every Friday, notices posted at least 72 hours before any shutdown, a single phone number answered by Harborline's site coordinator during working hours, and a monthly update at the hospital's staff forum. Complaints were logged, answered within one working day and reviewed at the weekly coordination meeting.