Is Your Wet-Pipe Sprinkler System Ready for Winter? 7 Steps to Prevent Frozen and Busted Pipes Before the First Freeze

A wet-pipe sprinkler system is dependable when its piping and the water inside it remain above freezing. But when cold weather reaches an unheated or poorly protected space, a short period of heat loss can put the system, and the building, at risk.

For building owners, facility managers, warehouse and distribution operators, industrial plants, schools, hospitals, and property managers, winter preparation should begin before temperatures drop. A fall inspection can identify cold spots, damaged insulation, and other conditions that could lead to busted fire sprinkler pipes, water damage, system impairment, and operational downtime.

Why wet-pipe sprinkler systems are vulnerable to freezing

Wet-pipe systems hold water in the piping. If that water freezes, it expands and can rupture a pipe, fitting, or sprinkler component. The damage may not become apparent until the ice thaws and water escapes.

The exposure is not limited to exterior pipework. Wet-pipe sections can be at risk in:

• Attics and roof spaces

• Loading docks and areas near exterior doors

• Parking areas and other open or semi-enclosed spaces

• Crawl spaces and unheated mechanical rooms

• Exterior walls and poorly insulated ceiling cavities

• Vacant tenant spaces where heating has been reduced or shut off

The resulting damage can spread quickly: a frozen section may split, thawing water can flood inventory and equipment, and the affected system may need to be taken out of service while repairs are made. This creates a life-safety impairment as well as a property and business-continuity risk.

Seven steps to prepare before the first freeze

1. Identify every wet-pipe section exposed to cold

Walk the building with current system drawings and identify where wet sprinkler piping passes through unheated or heat-loss-prone spaces. Do not assume that a heated office means the entire building is protected. Check attics, dock areas, parking structures, crawl spaces, exterior-wall cavities, and spaces with limited access.

Pay particular attention to locations that may be overlooked during routine rounds. A change in tenant, building use, or operating schedule can alter how much heat reaches a previously protected area.

2. Repair building-envelope problems

Cold drafts and water intrusion can compromise freeze protection. Check for broken or poorly sealed windows, gaps around doors and penetrations, damaged wall or roof insulation, and roof leaks above sprinkler piping.

Make repairs before winter conditions arrive. Keep loading-dock doors closed when not in use, and ensure weather seals and door closers function properly. Persistent drafts can create localized cold zones even where the building’s central heating system is operating.

3. Inspect insulation and heat tracing

Check insulation on exposed piping for gaps, compression, moisture, or physical damage. Wet or displaced insulation may not provide dependable protection.

Where heat tracing is installed, verify that it is appropriate for the application, listed for its intended use, powered, and functioning as designed. Inspect associated controls and sensors, and address damaged wiring or failed components through qualified personnel. Insulation and heat tracing should be evaluated as part of the system’s freeze-protection arrangement, not assumed to be effective simply because they are present.

4. Verify heat in concealed and low-traffic spaces

Confirm that spaces containing wet piping will remain warm throughout the winter, including during nights, weekends, holidays, and building shutdowns. NFPA 25 guidance commonly uses 40°F as the minimum temperature for areas with wet-pipe sprinkler systems that rely on heat for freeze protection. Treat this as typical guidance, and confirm the applicable requirement with the Authority Having Jurisdiction (AHJ).

Check thermostats, low-temperature alarms where provided, and building controls. Reassess tenant spaces after a vacancy or tenant change. Reduced heating, disconnected controls, or a new operating schedule can leave sprinkler piping exposed without obvious warning.

5. Verify antifreeze type and protection level

If the system includes an antifreeze solution, verify its type, concentration, and freeze-protection level using the applicable testing method and requirements. NFPA 25 provisions have changed: listed antifreeze solutions are generally required for new installations, while treatment of existing legacy solutions depends on the adopted edition and specific conditions. Older glycerin or glycol solutions may not comply with current requirements.

Do not top up or replace antifreeze with an unverified product. A qualified fire protection contractor can help determine whether the solution is acceptable and document the test results. The National Fire Sprinkler Association’s winterization guidance discusses cold-weather considerations for sprinkler systems.

6. Maintain dry-pipe components in mixed systems

A facility with wet-pipe zones may also have dry-pipe or preaction sections. Before freezing weather, check that low-point drains and auxiliary drains are identified, accessible, and maintained according to the system requirements. Water left in low points can freeze, obstruct operation, or damage components.

If the facility has dry sprinklers, verify their age and testing schedule. Dry sprinkler heads are tested every 10 years, so confirm their last test date is on record and that the next test is not coming due during freezing weather. Confirm the applicable schedule with your fire protection contractor and AHJ.

7. Document conditions and schedule a professional inspection

Record cold-prone locations, temperature checks, insulation or heat-tracing repairs, antifreeze test results, drain maintenance, and outstanding corrective actions. Keep the system’s impairment procedure accessible and ensure responsible staff know how to initiate it.

A pre-winter professional inspection can help identify concerns that a routine building walk-through may miss. It can also help coordinate repairs, required testing, and documentation before severe weather or a system impairment occurs. For additional maintenance considerations, see our article on fire sprinkler maintenance and avoiding busted pipes.

Early warning signs to address during fall inspections

Look for conditions that indicate freeze protection may be inadequate or that the system has been exposed to cold in the past:

• Corrosion, leaks, or signs of previous freeze damage

• Missing, wet, or damaged pipe insulation

• Heat-tracing components that appear damaged or are not operating

• Drafts near sprinkler piping, exterior doors, or windows

• Spaces where heat has been reduced or shut off

• A recent tenant change or building-use change

• Uncertainty about antifreeze type, concentration, or records

If you find a concern, document it and arrange qualified follow-up. Do not assume a pipe is safe because it has not yet leaked.

Common winterization mistakes

Several preventable oversights can expose piping to freezing conditions:

• Assuming the entire building is heated because occupied areas are comfortable

• Forgetting vacant tenant spaces or rooms with independent thermostats

• Skipping the attic, crawl space, or loading dock during the inspection

• Using unlisted or unverified antifreeze

• Propping open exterior or loading-dock doors

• Treating insulation or heat tracing as effective without checking its condition and operation

What to do if a sprinkler pipe freezes

If you suspect a frozen pipe, contact your fire protection service provider promptly. Do not use an open flame or other uncontrolled heat source to thaw piping; this can damage the system or create a fire hazard.

If a pipe has ruptured or the system must be shut down, follow the facility’s impairment procedures. Notify the appropriate parties, including the monitoring provider and AHJ where required, and implement a fire watch or other compensatory measures as directed by the impairment plan and applicable NFPA 25 requirements. Do not return an impaired system to service until qualified personnel have completed the necessary repairs and restoration checks.

How Safeway Fire Protection can help

Safeway Fire Protection provides fire sprinkler maintenance, inspections, and service for commercial and industrial facilities. We can support pre-winter inspections, evaluate heat-tracing and insulation concerns, verify antifreeze condition, review system documentation, and repair busted pipes.

Addressing cold-weather risks early helps reduce the likelihood of water damage, unplanned downtime, and extended system impairment. Learn more about our fire protection services or contact Safeway Fire Protection to discuss your facility’s needs.

Disclaimer: Requirements depend on the adopted NFPA 25 edition, system type, occupancy, local amendments, and the AHJ. Confirm applicable requirements with your fire protection contractor and AHJ.