Why commercial differs from residential
The physics is identical. Everything else is different.
Scale. A commercial line running unnoticed does far more damage per hour than a domestic one, and a large building can have several vulnerable runs a long way from anyone.
Occupancy. A house has someone in it who notices a tap running slow or a cold patch on a wall. A closed business has nobody, sometimes for days.
Setback heating. The energy-saving practice of dropping temperature during a closure is exactly the thing that lets peripheral areas drop below freezing. That is the most common cause of holiday-weekend commercial freeze damage, and it is a policy decision rather than an accident.
Consequences beyond repair. Lost trading, damaged stock, ruined tenant space, and potential liability. A burst pipe in a retail unit is a closure, not an inconvenience.
Systems homes do not have — fire suppression, rooftop units, commercial kitchen equipment, backflow assemblies on larger services.
Worth knowing
Establish before the season who is responsible for what. In a leased property, freeze protection frequently falls between landlord and tenant, and that gets discovered during the event rather than before it. Get it in writing.
The vulnerable places
Freeze damage is not evenly distributed. It concentrates in a predictable short list.
- Unheated storage, stock rooms and back-of-house areas that get no conditioning and no attention.
- Roof spaces and above suspended ceilings, where pipe frequently runs above the insulation rather than below it.
- Exterior walls, particularly north-facing, and anywhere behind fixed cabinetry that blocks room heat.
- Fire suppression risers and wet systems in unheated areas. A frozen sprinkler line is both a plumbing failure and a life-safety failure, and it will not be discovered until it is needed.
- Rooftop equipment and its supply and condensate lines, fully exposed.
- Exterior hose bibs, irrigation and backflow assemblies — the assembly is above ground, full of water and completely exposed.
- Loading docks, vestibules and anywhere a door stands open repeatedly during the day.
Before the season
Walk the building looking for pipe, specifically in the areas above. Most facilities managers can name the mechanical room; far fewer know what runs above the stock room ceiling.
Insulate exposed runs and pay attention to joints and elbows, where gaps get left.
Set a minimum temperature, not off. Whatever setback the closure policy uses, establish a floor that keeps peripheral areas above freezing — and confirm the peripheral areas actually reach it rather than assuming the thermostat reading applies building-wide.
Disconnect hoses, drain irrigation, insulate backflow assemblies.
Have the fire suppression system checked by whoever services it, specifically for freeze exposure in unheated areas. This is not general plumbing work.
Locate and label every shutoff — main, zone and tenant — and confirm each actually turns. Then make sure more than one person knows where they are.
Seal draughts where pipes pass through exterior walls and at dock doors.
Planning for a closure
This is the part that prevents most commercial freeze losses, and it is process rather than plumbing.
Assign someone to check the building, with a defined frequency during any multi-day closure and a forecast trigger for checking more often. Somebody physically walking the vulnerable areas is worth more than any single device.
Consider remote monitoring. Temperature sensors in the vulnerable spaces and water sensors near equipment cost little relative to a burst, and they alert somebody while it still matters.
Write down the response. Who to call, where the shutoffs are, what to isolate first. During an event, at night, that document is worth more than expertise nobody can reach.
Consider draining what is not needed — irrigation, unused exterior lines, seasonal equipment.
Check insurance terms. Many commercial policies require a maintained minimum temperature or reasonable precautions during closure. A claim can be affected by a setback that seemed sensible at the time.
During and after a freeze
Drip the taps served by vulnerable runs — furthest from the heater, and anything through a roof space or exterior wall. A steady trickle on hot and cold.
Open cabinets and interior doors so heat reaches peripheral spaces.
If a fixture stops flowing, act immediately. That is a frozen line that has not burst yet, and there is a short window. Leave the tap open to relieve pressure and warm the run gently — never with an open flame.
The thaw is when you find out. Ice that split a pipe is also plugging it, so nothing leaks until it melts. Walk the entire building as temperatures come back up, checking ceilings, unheated areas, and every hose bib.
That post-thaw inspection is the single most valuable hour in this whole process, and it is the one most often skipped because the cold has passed and everyone assumes the risk has with it.