Repairing flood damaged buildings

Codewords 118: April 2024

The severe weather events that hit many regions across Aotearoa/New Zealand in 2023 resulted in damage to thousands of buildings. Remediation and recovery work continues.

Before you start 

Before you start repair or remediation work on buildings affected by flooding you should:

• ensure the building is safe to enter 
• take photos before and during the work
• take appropriate Health and Safety precautions, including wearing safety gear, and ensuring power and gas are turned off
• ensure that the sewerage system has been checked and presents no risk to health. Floodwater may be contaminated by silt and sewerage that is deposited as water recedes.
• check your local council’s website for current guidance for repair work, if any.

MBIE have produced some guidance that may help:

Removal of silt deposited during flooding - quick guide [PDF 1.3MB](external link) — Building Performance

Slope Stability - quick guide [PDF 4MB](external link) — Building Performance

Starting the work 

Once you know what work is needed you should check if it needs a building consent.

CanIBuildIt.govt.nz(external link)

If a building consent is required, your client must obtain this before you start the work. If the work needs to be done urgently to save or protect people’s lives or health, or to remove a risk of serious damage to property you should contact your local council. They will be able to advise you if you can proceed with the work and apply for a certificate of acceptance after the immediate danger has been removed or reduced.

All work must comply with the Building Code to the extent required by the Building Act, even if a building consent is not required.

Schedule 1 exemptions of the Building Act 

The list of building work that does not require a building consent is provided under Schedule 1 of the Building Act and includes specific conditions to manage risk.

Schedule 1, Building work for which building consent is not required(external link) — Legislation New Zealand

When you start repair work you may find that the extent of the damage is larger than you originally thought. In that situation a building consent may be required, so you should contact the property owner and local council to discuss.

Some of the exemptions that may apply to remediating flood damaged buildings are:

Territorial and regional authority discretionary exemptions 

This exemption allows local councils to use their discretion to exempt any proposed building work if it complies with the Building Code and is unlikely to endanger people or buildings. This discretion can be used to exempt proposed building work from the requirement to obtain a building consent if:

• the completed building work is likely to comply with the Building Code, or
• if the completed building work does not comply with the Building Code, it is unlikely to endanger people or any building, whether on the same land or another property.

General repair, maintenance and replacement

This exemption allows building owners to maintain their buildings (including carrying out any repairs or replacement) without having to get a building consent.

The following can be repaired, maintained and replaced if comparable building products or assembly is used, and, in the case of a replacement, it is in the same position:

• building products
• assemblies incorporated in or associated with a building.

This clause cannot be used if a complete or substantial replacement of a specified system is required, or the product contributes to the building’s structural behaviour or fire safety properties.

Internal walls and doorways in an existing building

Building work in connection with an internal wall (including an internal doorway) in any existing building doesn’t usually need a building consent unless the wall is any of the following:

• load bearing
• a bracing element
• a fire separation wall (also known as a firewall)
• part of a specified system
• made of brick, stone, concrete (or similar) joined with mortar.

Repair and replacement of plasterboard due to flooding

When a flooding emergency happens and walls have been damaged, it is likely that the plasterboard will need to be partially or completely replaced.

It can be difficult to identify the type or purpose of plasterboard without expert knowledge or information. The building consent plans will usually show where the different types of plasterboard are located, and these plans, if available, can be obtained from your local council.

To help identify the type of plasterboard, you can take photos of the fixings and any information on the back of the plasterboard if you remove it, or you may be able to find out the use and purpose based on its location.

If you are unsure, it is safer to treat all plasterboard as if it is a bracing element and take appropriate measures to repair it.

Before starting repairs, it is important that any cavity spaces, such as between cladding and building wrap where silt and other contaminants may have collected, have been cleared out, and that all timber framing is dry and in good condition.

Consider the safety risks to yourself and others. Make sure you and anyone working on your behalf have the correct equipment and resources. 

Repair and replacement of plasterboard due to flooding(external link) — Building Performance

What information do you need to provide? 

You may need to provide a record confirming what work has been completed. The information could consist of a written or drawn record of the repair, a producer statement for construction work (PS3), certificates from any specialist trades such as electrical certificates of compliance, or a record of work for any restricted building work completed.

This information should be provided to the property owner, and if the work is done under a building consent, the record of work must also be provided to the local council.

Further guidance 

Remediation, repair and, urgent Works(external link) — Building Performance

Building consent exemptions for damaged buildings - quick guide [PDF 1MB](external link) — Building Performance

Building work that does not require a building consent(external link) — Building Performance

Flood damaged buildings(external link) — Building Performance

Quiz

1. What must you do before beginning any repairs or remediation to a flood damaged house?

1. ensure the building is safe to enter
2. take photos before and during the work
3. take appropriate H&S precautions, including wearing safety gear, and ensuring power and gas are turned off
4. check your local council’s website for information about the current and any guidance for repair work.
5. All the above

2. If you can’t identify which walls require bracing when you’re replacing the plasterboard:

1. It’s safer to treat all plasterboard as if it is a bracing element.
2. Just brace some of the walls.
3. Don’t worry about bracing, the house is still standing.
4. Wait for the building inspector to tell you.

3. How can silt damage buildings?

1. silt can block subfloor vents that help to keep the subfloor dry
2. silt can trap moisture in framing such as piles, bearers or joists. This can lead to rot or damage.  
3. silt and water loading can dislodge walls and floors.
4. silt build-up can prevent water draining away from the building leading to ponding against building elements which in turn can cause damage.
5. All the above