Water damage prevention and mitigation guide for buildings under construction

Water damage during construction presents a significant risk to project schedule, cost, safety, and long‑term building performance. This guide is designed to help develop and implement best practices to help prevent, detect, respond to, and mitigate water damage arising from:

• Temporary construction water sources and distribution pipes, hoses and facets 
• Inclement weather and flooding
• Defective or incomplete building envelope
• Faulty design, installation or testing of plumbing, mechanical and fire suppression systems
• Vandalism or unauthorized access
• Equipment and materials subject to moisture damage while stored and installed

Objectives

Explore our guide below to learn more on several related topics.

Roles and responsibilities

Owner/Risk manager

• Approves this guide and ensures compliance
• Requires documentation and audits compliance
• Reviews and update guide on a routine basis 
• Evaluates and authorizes implementation of water sensing technology to assist with identification and notification of water intrusion events 
• Reviews the project documents for specific water damage prevention requirements and/or QA/QC procedures 
• Reviews builders risk policy for required water damage prevention safeguards 

General/prime contractor (GC)

• Oversees overall responsibility for implementation
• Maintains valve isolation schedules, isolation maps and water intrusion response plan
• Coordinates inspections and system charging safeguards 
• Develops and implements quality control/quality assurance policies 
• Maintains site security 
• Upholds prequalification of subcontractors, scope and submittal reviews 

Trade contractors

• Follows quality control and testing requirements
• Protects work and report deficiencies immediately
• Provides project-specific water damage prevention and mitigation procedures 
• Maintains materials and equipment subject to moisture damage for direct contact with floors

Site superintendent

• Maintains daily oversight of water damage prevention and mitigation policies 
• Always ensures emergency response readiness

Risk identification and controls

Temporary water sources and distribution

Risks

• Hose rupture or disconnection during working and non-working hours 
• Unattended pressurized lines 
• Poor-quality fixtures and fittings

Controls

• Use construction grade hoses – rated for continuous pressure (high pressure rating, high burst rating, high/low temperature rating and abrasion/kink resistant)
• Temporary water must be isolated at the end of each shift
• No temporary hoses may be left pressurized while unattended 
• Hoses must be: 
  • Mechanically protected from traffic and sharp edges
  • Connected using threaded or cam-lock fittings (no friction-fit)
• Shutoff valves required: 
  • At source
  • At floor or zone level
  • Capable of being locked out of service 
• Shall be located outside of the structure, to extent feasible
• Monitor auxiliary water pumps to prevent over pressurization and consider unplugging on nights and weekends

Inclement weather and flooding

Risks

• Freezing temperatures 
• Wind-driven rain
• Snow melt
• Site drainage failures
• Clogged, obstructed or disconnected roof drains 
• Sub-grade doors, windows and unprotected foundation core holes 

Controls

• Maintain positive drainage sloped away from the structure
• Provide temporary roof and opening protection
• Seal floor penetrations during active construction
• Daily review of weather forecasts for: 
  • Severe weather  
  • Heavy rain
  • Freezing conditions
• Place temporary flood barriers where groundwater or stormwater risk exists
• Maintain operational sump pumps and backup power where required
• Seal below grade core holes upon drilling 
• Inspect below grade stair drains for obstructions
• Implement a temporary heat plan 

Building envelope protection

Risks

• Incomplete façades, siding and roofing 
• Temporary weather protection 
• Exposed openings
• Improper sequencing
• Seeping moisture associated with poor design or incompatible materials 

Controls

• Utilize wall mock-ups to evaluate the design and material compatibility 
• Temporary weather enclosures at: 
  • Roof perimeters
  • Curtain wall and window openings
• No permanent interior finishes installed until: 
  • Building is dry and weather tight 
  • Envelope inspections are complete 
• Perform interim water testing of envelope assemblies prior to interior close‑in
• Exterior stair landings and balconies slope away from doorways

Inspecting and protecting porous building materials

Risks

• Building materials susceptible to wetness, moisture and humidity can cause staining, mold growth, delamination, warping, softening or other physical damages
• Materials with long lead times can cause delays in construction schedules and completion dates

Controls

• Visually inspect building materials upon arrival and while staged
• Photograph all deliveries and record suspected damage in inventory logs or reject the items immediately
• Keep all materials elevated off a minimum of four inches of the floor level, using racks, pallets or cribbing
• Stage materials to allow proper airflow, preventing condensation
• Store materials in dry, well drained areas isolated from standing water or runoff
• Use containers, enclosed rooms, trailers or covered platforms when available to limit outdoor storage
• Materials stored outside shall be wrapped on five sides (top + four sides) leaving the bottom open for ventilation
• Evaluate materials for priority sequencing and perform routine moisture testing on wood/gypsum, ambient air and concrete / masonry surfaces prior to installation

Vandalism and unauthorized access

Risks

• Malicious valve opening of hoses, sinks, toilets and mechanical systems 
• Theft or damage to piping and fixtures 

Controls

• Consider use of motion activated electronic alarm system connected to a UL listed centrally monitored alarm station 
• Secure building with perimeter fencing and controlled access points
• Lockable valve handles on major shutoff valves
• Nighttime lighting and security patrols
• Signage identifying emergency water shutdown locations

Valve isolation and automated controls

Valve isolation maps

• Develop and maintain site‑specific valve isolation maps, including: 
  • Domestic water
  • Hydronic systems
  • Fire protection (temporary and permanent)
• Maps must show:  
  • Valve ID numbers
  • System served
  • Location by floor and grid
• Laminated copies required at: 
  • Site office/job trailers 
  • Fire command center, security desk or main entry
  • Conspicuous locations posted on safety message board and/or elevator lobbies 
• Maps updated as systems are extended or modified
• Consider color coded system, ribbons or tags to indicate proper isolation valves 

Automated and monitored shutoff devices

Where feasible and commensurate with risk:

• Use automatic water shutoff valves on: 
  • Temporary domestic water feeds
  • Permanent systems once commissioned by zone
• Devices should include: 
  • Flow anomaly detection
  • Floor moisture/high humidity notification 
  • Remote alert capability (text/email/app)
• Fire protection systems shall only use approved devices and methods that do not impair life safety compliance
• Automated alarm response procedures should be assigned and communicated to responsible parties

Quality control and inspection criteria

Documented inspections

All piping systems must undergo documented inspections prior to charging, including:

• Visual inspection of: 
  • Joints, caps, plugs and terminations
  • Temporary dead ends
• Verification that: 
  • All downstream openings have final connections, caps or secured valve-isolation 
  • Supports and restraints are installed
  • Water flow alarms and sensors are communicating with monitoring stations

Inspection documentation

• Date, system, zone and inspector
• Deficiencies noted and corrected
• Retained in project quality records

Craftsmanship and installation controls

• Compare submittals to onsite materials / equipment prior to installation 
• Only trained and authorized personnel may modify piping
• No temporary caps made of tape, plastic wrap or friction-fit devices
• All abandoned or future connections must be: 
  • Permanently capped
  • Tagged and documented

Procedures for charging piping systems

Pre-charge checklist

• Approved inspection sign-off
• Updated valve isolation map
• Notification to GC and affected trades
• Adequate manpower available to identify and communicate leaks or defects 

Charging protocol

• Systems charged incrementally by zone, not all at once
• Pressure increased slowly while monitoring: 
  • Joints
  • Valves
  • Equipment connections
• No charging outside of normal working hours unless approved, avoiding 24 hours before non-working weekends or holidays 

Post-charge monitoring

• Inspect system for leaks immediately after pressurization
• Re-inspect after 24 hours
• Maintain isolation until area is ready for occupancy or next phase

Leak detection and early warning

• Daily walkdowns of active water systems
• Moisture sensors recommended in: 
  • Mechanical rooms
  • Vertical shafts
  • Areas below active piping
  • Areas with concentrations of high valued / long lead time finishes 
• Temporary floor drains kept clear and operational
• Any leak, regardless of size, must be reported and responded to immediately

For information on Water sensor flow and leak detection technology vetted for reliability by The Hanover, please visit our Risk Solutions page.

Learn more

Prompt response and mitigation plan

Maintain state of emergency readiness 

Preparation:

• Response team aware of roles and responsibilities 
• Isolation valve maps posted in job trailer and conspicuous locations
• Water intrusion response kit onsite and easily accessible 
  • Staging locations posted in conspicuous locations
  • Accessible to all trades
  • Response kit may include water catch bin / barrels, floor squeegees, mops, absorbent pads, sprinkler head shut off tool, sump pumps and adequate hose lengths and other additional means to collect, move or isolate water

For a list of a water damage response and mitigation contractors who have been vetted for reliability and pricing structure by The Hanover, please visit our Risk Solutions page. 

Learn more

 

Immediate actions

Upon discovery of a water release:

• Stop the water using nearest isolation valve
• Notify: 
  • Site superintendent
  • GC project manager
  • Responsible trades 
• Protect personnel and electrical systems
• Contain spread of water using barriers and drains
• Maintain possession of damaged/defective hoses, pipes, fixtures, fittings, valves, sprinkler heads and mechanical equipment as part of incident investigation and claim mitigation

Mitigation and recovery

• Initiate drying within 24 hours to prevent mold growth
• Engage qualified water mitigation professionals as required
• Remove and document damaged materials
• Photograph affected areas and retain records

Reporting and root cause analysis

• Incident report completed within 24 hours
• Identify: 
  • Source
  • Contributing factors
  • Corrective actions
• Update procedures to prevent recurrence
• Notification to insurance carrier – do not delay in effort to assess damages 

Training and compliance

• All site personnel trained on:
  • Location of main shutoff valves
  • Leak reporting process
• This guide is incorporated into: 
  • Site orientation
  • Safety meetings
• Non-compliance subject to corrective action

Conclusion

Consistent application of these suggested controls is designed to help significantly reduce the likelihood and/or severity of water damage during construction. Each location may have its own characteristics which should be considered when reviewing and implementing these controls. The same policies and procedures should be implemented for any offsite storage locations. 

This material is provided for informational purposes only and does not provide any coverage or guarantee loss prevention. The examples in this material are provided as hypothetical and for illustration purposes only. The Hanover Insurance Company and its affiliates and subsidiaries (“The Hanover”) specifically disclaim any warranty or representation that acceptance of any recommendations contained herein will make any premises, operations or actions safe or in compliance with any law or regulation. By providing this information to you, The Hanover does not assume (and specifically disclaims) any duty, undertaking or responsibility to you.  The decision to accept or implement any recommendation(s) or advice contained in this material must be made by you.

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