Removing water and identifying damage to buildings

Learn how the flooding may have damaged key elements of your building and the potential risks associated with such damage.

Water should be removed from the building as soon as practicable, so long as other properties are not impacted.

Where the subfloor is lower than the surrounding ground (eg a basement), it may take some time for water to stop accumulating.

Sections five and six of the BRANZ guide: restoring a home after flood damage, has useful information about how to remove water from the building.

BU666 Restoring a home after flood damage -

Auckland Council has some simple guidance on how to prevent flooding and blockages on your property.

Reduce flooding risks on your property -

Your local Council may also provide similar resources.

Identifying potential flood damage to building elements

It is important to consider how the flooding may have damaged key elements of your building and the potential risks associated with such damage. This will:

  • help identify what remedial work may be needed
  • help identify what risks to the building may need to be considered
  • help you to carry out any remedial work safely
  • assist in discussions with your local council, insurers and building professionals
  • help in ensuring that any repairs carried out bring the building back into compliance.

Photos and records are very important and will help in any future discussions.

If you can do so safely, it is recommended that you inspect the following elements of your building and note any potential risks or damage. The following sections provide you with some suggestions on what to check for.

Retaining structures and adjacent


  • Are there signs of movement, recent or ongoing, such as cracking, fallen debris, rockfall or loss/tilting of vegetation?
  • Are there signs of damage to any pipes or cables that may be buried in the slope? This may include sinkholes.
  • Have any such services been exposed and are no longer supported by the soil?
  • Are there signs of significant erosion at the base of the slope?
  • Are there signs of Bulging ground appearing at the base of a slope or retaining wall?
  • Are there signs of water breaking through ground surface and/or pooling at the base of the slope and retaining walls in new locations?

Retaining walls:

  • Are there signs of movement or instability? For retaining walls this may show as the wall tilting or bulging outwards.
  • This may include loss of material or support at the base of the wall in front of its footings. Other typical signs include gaps and/or cracks developing in the ground behind retaining walls.
  • Are there signs of damage to the retaining wall?
  • Typical damages include cracking, displacement of wall back-fill and missing components to the wall.
  • Are there signs of damage or blockage to retaining wall drainage?
  • This could lead to water building up behind the wall and causing excessive pressure.
  • Are there signs of additional loading (surcharge) on the wall from movement of material at or upslope of the top of the wall?


Timber foundations, piles and poles:

  • Are there obvious signs of damage or movement out of alignment?
  • Are there signs of loss of support? Is the structure being supported showing tilting or sagging?
  • This may include recent exposure of concrete pads or encasement, or longer lengths of pile being exposed.
  • Are there any signs of movement in the walls that may indicate loss of support from the foundations? This could include bowing of the walls (inwards or outwards) or tilting.

Concrete slabs and foundations:

  • Are there signs of loss of support? Is the structure being supported showing tilting or sagging?
  • This could be visible externally around the edges.
  • Or, it could be noticeable internally through cracking, deflection or hollow sounding patches indicating loss of support.

Also consider other elements that may be supported on foundations such as:

  • Carports
  • Decks
  • Access pathways
  • Handrails or ramps
  • Large fences
  • Pools
  • Sheds.

Electrical and gas systems

Electric shock – supply should be isolated until initial checks have been carried out and the supply and installations are confirmed as safe by a registered electrician.

Leaking gas – supply should be isolated until checked and tagged as safe by a registered gasfitter.

Switches, outlets and fixtures:

  • Were any electrical outlets, switches or fixtures submerged below the water level? The power to these should be switched off or disconnected until they can be checked by an electrician.
  • Air Conditioning Split systems. Condensing units sitting at ground level that have been flooded need to be checked be Qualified person before using.


  • Has the meter board or distribution board been flooded?
  • Are there indications of a fault with fuses tripped or tripping continuously?
  • Are there electrical circuits or systems no longer working or working incorrectly?
  • If lights start to flicker there may be an electrical fault.

Internal plumbing systems


  • Is water failing to drain properly from toilets, sinks, showers etc?
  • Are any fixtures not operating correctly or showing signs of leaking or movement?

Drinking water:

  • Does the water look, smell or taste different?
  • Is the flow rate different?

Hot water system:

  • Is there damage to the gas or electricity supply to the water heater?
  • Have electrical or gas components of the water heater been submerged? These may need to be checked by an electrician or gasfitter before using again.
  • If you have no hot water, contact a plumber.
  • If your water heater has been partially or fully submerged, contact a plumber to check it is safe
  • Is the flow rate or temperature different?
  • Are there signs of movement of the cylinder or damage to the connected pipework?
  • If the system is elevated, are there signs of damage to the supports or fixings?

External drainage and guttering

  • Do gully traps overflow when using toilets, showers, basins, tubs and baths?
  • Are there signs of damage or blockage to external drainage – stormwater, wastewater?
  • Are there signs of guttering or external drainage blocking or not draining freely?

Building structure

Suspended timber floors (ie floors supported by joists and piles over a subfloor space):

  • Has the floor been submerged? Some wood products such as particle board are likely to need replacing if they have been in prolonged contact with water.
  • Has the floor become uneven?
  • Does the floor have areas that are bulging or swollen?
  • Are there any new gaps or cracks in the floor or at its perimeter?
  • Are there any indications of sogginess or springiness in the floors that indicate the timber may be damaged?

Floor coverings (vinyl, timber overlay products):

External wall cladding:

  • Is there any physical damage to the external wall cladding due to the pressure of water or to impact from debris. Damage could include broken, bent or missing cladding components, flashings, sealants etc.
  • Is there any cracks or gaps in the cladding? Cladding components may have swollen or shrunk with changes in moisture content.
  • Has the cladding developed soggy areas or soft spots which might indicate the presence of water that has been absorbed by cladding materials?
  • Is there new staining, discolouration, or surface damage to finishes such as paint?

Internal wall and ceiling linings:

  • Note - many residential buildings use timber framing as the wall structure to provide support to the roof, other floors and overall stability. In many cases, the linings are a key part of this support structure and their complete removal for an extended period of time may lead to unacceptable performance of the building.
  • Have any part of the internal wall and ceiling linings been submerged below the water level? Water may have also been drawn up above the water line in absorbent wall lining materials.
  • Is there any new swelling, cracking, gaps, unevenness or bulges in the linings, or in trim such as skirtings, architraves and scotias?
  • Is there new staining, discolouration, or damage to finishes such as paint or wallpaper?
  • Do doors and windows stick or not close properly due to movement, swelling or bulging in the wall, door or window frame, door leaf or window sash?
  • These walls may be required to be fire rated to prevent spread of fire from one property to the next. If there is any damage it must be repaired or replaced with a system that has an equal or higher fire rating.

Timber Framed Walls

  • Note: Take care not to damage the wall framing (studs – vertical, dwangs – horizontal, bottom plates) and the connection elements (nails, screws, plates or hold down bolts and brackets) when removing linings.
  • Are there signs of damage to the framing due to prolonged water exposure?

Concrete or masonry walls

  • These types of walls can perform well under short term exposure to water. However, they can absorb water and moisture and should be left to dry before being relined.
  • Take care when digging or clearing around the outside of these walls as they may have a waterproofing coating or boarding to the outside. This is often the case if they are basement walls below ground.


  • Did the roof cladding become submerged?
  • If the building has undergone significant movement at the foundations, check to see if any part of the roof, including its flashings and sealants, have become physically damaged.
  • Is any part of a roof cladding that was submerged absorbent (eg concrete roof tiles, timber shingles, plywood roof components in flat roofs).
  • Are there any new cracks, gaps or holes in the roofing? Has it become uneven?

External structures – decks, carports, bridges, paths:

  • Have these become uneven or are they sagging?
  • Is there any sign of loss of support from the soil?


  • Has the insulation become wet, either through submersion or, for absorbent insulations, from contact with adjacent wet materials?

Smoke alarms or other safety devices:

  • Do any smoke alarms show signs off water damage?
  • Does the smoke alarm activate when the test button is pushed?
  • Excessive humidity or damage may cause smoke alarms to activate as well, creating nuisance alarms.

Heating and cooling systems:

  • What parts (if any) of the heating and cooling system have been wetted?

This list is in addition to potential damage to other non-building elements such as appliances, carpets, etc.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: