Working on an occupied commercial building

The programme has to admit the building is in use

An occupied job takes longer than the same job on an empty building, and it should be priced and programmed that way from the start. The additional time is not in the rooflight work. It is in the setting up and taking down each day, the enclosure of the space below, the isolations, the escorted access, and the fact that certain operations can only happen in certain hours.

The failure mode is a programme written as though the building were empty, then compressed when reality arrives. A realistic version has the constraints listed as line items so the client can see what each one costs in days and decide whether to relax it. That is a better conversation than a job overrunning.

Permits to work before the first fixing comes out

Most occupied commercial buildings of any size run a permit system, and roof work almost always requires one. A roof access permit, a hot works permit where any flame or heat is involved, and sometimes a separate permit for work above occupied areas or near services.

Permits take time to issue and they are issued by a named person who may not be on site every day. On a job starting Monday, the permit conversation happens the previous week. Where the client is a tenant rather than the owner, the permit often has to come from the managing agent, which adds another party and another few days. It is worth establishing at survey who issues permits and how long they take.

Detector isolation and avoiding an evacuation

Cutting, grinding and even lifting a dusty ceiling tile will set off a smoke detector, and in a large building that means a full evacuation, a fire service attendance, and a very difficult afternoon.

The arrangement is straightforward and non-negotiable: the detectors in the affected zone are isolated by whoever is authorised to do it before work starts, the isolation is recorded, a written watch arrangement covers the area while detection is off, and the zone is put back into service at the end of every working day rather than at the end of the job. Isolating detection is a client-side action taken by their responsible person. Our part is knowing precisely which zones and asking early enough.

Escape routes, and the ones created by accident

Two things happen to escape routes on an occupied job. The obvious one is obstruction: material stacked in a corridor, a tower scaffold in a lobby, a fire door wedged for cable. All avoidable with a walk of the route before the first delivery.

The less obvious one is a new opening between compartments. Trimming through a ceiling, breaching a cavity barrier over a partition head, or leaving a service penetration unsealed at the end of the day creates a route for smoke that the fire strategy did not anticipate. Anything opened has to be closed at the end of each shift with the appropriate fire stopping, not left until making good.

Asbestos registers and the survey you must be shown

Any non-domestic building constructed before 2000 has a duty holder required to manage asbestos in it, and that means a register exists or should. Ceiling tiles, insulation board around service risers, textured coatings, rope seals and cement rooflight surrounds are all places it turns up on a rooflight job.

We ask to see the register or the refurbishment and demolition survey covering the specific areas we are opening, before we open them. Where nothing exists for that area, the work waits until a survey is done. This is not caution for its own sake: opening a ceiling containing asbestos insulating board contaminates the space below and turns a three-day job into a very expensive month.

Protecting what is directly underneath

Everything that comes off a roof falls into the space below unless it is stopped. The standard arrangement is a full enclosure below the opening: a rigid deck or boarded crash deck where anything substantial could fall, sheeting to floor level, and the enclosed zone fenced off with signage and physically closed rather than marked with tape.

Under that goes protection for what cannot be moved: machinery covered and sealed, stock sheeted, flooring boarded. What can be moved should be moved, and the negotiation about which desks, racks or displays relocate for the week is best had at survey when there is time to plan it. The detail is covered on our sibling page about protecting a working space below.

Dust routes nobody plans for

Dust does not stay in the enclosure if the building’s own air movement carries it out. The three routes people forget are the ceiling void, which frequently runs continuously across several rooms; the mechanical ventilation, which will happily distribute anything it picks up; and the door somebody props open for a cable.

The response is to seal the enclosure at the ceiling line rather than just at floor level, to have the air handling serving that zone shut down or its intakes protected while cutting happens, and to use on-tool extraction with a class M vacuum on everything that produces dust. In a food, clinical or laboratory setting, add a cleaning and sign-off step before the space is handed back, because visually clean and acceptably clean are different standards there.

Noise windows and the trades that cannot share them

The noisy phases of a rooflight installation are short and intense: cutting the opening, removing the old unit, fixing the new kerb. Everything else is quiet. That is useful, because it means the disruptive work can often be confined to a two or three hour band rather than spread across the week.

Where a building has quiet requirements, meeting rooms, consulting spaces, teaching, recording, the practical arrangement is agreeing fixed noise windows in advance, publishing them to the occupants, and holding to them. First thing in the morning before the space fills, or after close, are the usual choices. Whether out of hours working is available and what it costs is covered on our page about out of hours work.

Weathertight at the end of every shift

The roof is never left open overnight. On an occupied building that principle stops being good practice and becomes the single most important commitment on the job, because water arriving through a roof at two in the morning lands on somebody’s stock, servers or trading floor.

In practice it means the opening is sized to what can be completed and closed in a day, the new unit goes in the same shift the old one comes out wherever possible, and where a phase genuinely cannot complete, a temporary weathertight closure is formed and dressed properly rather than sheeted over. A tarpaulin weighted with blocks is not a closure. It is a delayed problem.

Deliveries, lay-down and city centre loading

Getting units to the roof is often the hardest logistical part of an occupied job. A large glazed unit is heavy, awkward and cannot go up a domestic ladder, so it needs either a hoist, a telehandler, a crane lift or a route through the building.

Each option has consequences. A crane lift needs a road closure or a private yard, a lift plan, and usually a Saturday. A route through the building means protecting floors and lift interiors and moving outside occupied hours. In central Oxford, add loading restrictions, bus gates, the zero emission zone and streets where a wagon cannot turn. Lay-down space for the old units coming off is the item most often forgotten, and there is rarely anywhere to put them.

Tenants, landlords and who has to consent

Where the client occupies under a lease, the rooflight work is usually an alteration requiring landlord consent, and often a licence to alter with a schedule attached. That process runs on solicitors’ timescales rather than construction ones.

Where other tenants share the building, they need telling, and their access, parking and quiet enjoyment have to be considered even though they are not paying for anything. A short written note to neighbouring occupiers giving dates, hours and a contact number prevents most of the complaints that otherwise arrive through the managing agent. Consent and insurance paperwork is dealt with on our page about commercial paperwork.

Clean rooms, kitchens, laboratories and stock

Some occupied spaces cannot tolerate the ordinary arrangements at all. A commercial kitchen operating under food safety controls will not accept dust in the production area during service, so the work happens overnight or the area closes. A laboratory with sensitive instruments may require vibration limits rather than only dust control. A clean room is a full decant.

Retail stock is its own category, because damage there is directly quantifiable and a claim is straightforward to make. The answer is to move it, not to sheet it, and to record with photographs what was in the area before work started. Where a space cannot be cleared, that constraint decides the programme.

Passes, keys and out of hours access

Security arrangements are worth settling in the first week. Who is issued passes, whether escorting is required, how the alarm is set and unset, who holds keys, what happens if somebody needs to leave at a time the building is locked, and what the arrangement is at weekends.

On sites with heightened security this extends to vetting and to restrictions on cameras and phones on certain floors. It is all manageable, and none of it is manageable at seven o’clock on the first morning with a wagon outside. Get it agreed in writing with a named contact and a mobile number that is answered.

Welfare, parking and the small logistics that stall a day

The unglamorous items cost real time. Where the team parks, whether permits are needed, where the welfare facilities are and whether they are available at the hours worked, where waste goes and whether a skip can be sited, where a power supply comes from and whether it is on a circuit that trips.

None of this is complicated. All of it stalls a start if it has not been resolved. On a survey we go through it as a list, because an hour lost every morning for a week is a day of the programme, and it is a day the client is paying for.

One opening at a time, and why sequencing matters

On a job with several units, the temptation is to open everything and work across them. On an occupied building that is the wrong sequence. Each opening should be taken from start to weathertight before the next is started, so that the exposure at any moment is one hole, one enclosure and one affected space.

It looks slower on paper and it is more predictable in practice. It also means that if the weather turns or the day runs short, the building is in a defined state rather than half open in four places. Where a larger roof needs a genuine phasing plan, that is covered on our page about programme and phasing.

Agreeing the constraints before the price is fixed

Every item above either costs time or does not apply, and which ones apply is a client-side answer. So the survey on an occupied building spends as long on the operational questions as on the roof: hours available, permit route, detection isolation, asbestos information, what can be cleared below, access and craneage, and who signs what.

We give a range by email from photographs and a description, then a fixed price once those answers exist, because on this kind of job the constraints move the number more than the units do. We install and replace rooflights only, so where a roof covering needs work first, we will say so. Call 01865 704245 or email info@heritageskylightsoxford.co.uk with the building, the use, the number of units and the hours you can give us.