Joinery Performance, Care & Warranty Guide

GENERAL

All timber joinery supplied by Dando Doors & Windows is manufactured to perform under New Zealand environmental conditions when correctly installed, coated, and maintained.

Timber is a natural material and requires appropriate protection and maintenance to ensure long-term performance.

The performance of timber joinery is dependent on correct installation, protection from moisture ingress, and the application and maintenance of a suitable coating system.

The selection of coating system is the responsibility of the builder, designer, or owner. Dando Doors & Windows provides guidance based on best practice for timber joinery performance; however, it is the responsibility of others to ensure that any selected coating system is suitable for the application and is applied and maintained in accordance with the coating manufacturer’s specifications.

DURABILITY

Our timber joinery products can be expected to have a trouble-free serviceable life of not less than 15 years as required by section B2 (Durability) of the New Zealand Building Code. This pertains specifically to the structural elements of the joinery.

Under NZBC B2/VM1, durability is required to be achieved with only normal maintenance, which includes washing of surfaces and the ongoing recoating of protective finishes. This confirms that protective coating systems are an essential component of durability compliance.

Durability can only be achieved where joinery is properly painted, sealed, and protected from moisture ingress at all times, including prior to and during exposure to weather.

In the course of normal use, decorative elements and non-structural fittings such as window fasteners, door rollers and the like may need to be replaced as they wear out. This does not contravene the B2 Durability requirements of the New Zealand Building Code or the warranty.

Decorative coatings are not covered by this warranty and should be covered by the coating supplier.

SITE STORAGE

All joinery products must be kept in a cool dry area free from moisture and direct sunlight immediately on arrival to site.

Your timber joinery must be stored on an even surface to avoid twisting and damage.

Joinery must be protected from rain, ground moisture, and construction activities at all times prior to installation and coating.

PAINTING AND COATING

All preparation and coating must be carried out in a tradesman-like manner and in accordance with AS/NZS 2311 – Guide to Painting of Buildings and the coating manufacturer’s specifications.

NZS 3602 and the New Zealand Building Code require timber joinery to achieve durability and be protected from environmental exposure in service. In practice, this is achieved through the application and maintenance of a suitable protective coating system to limit moisture ingress and maintain dimensional stability.

NZS 3602 requires that where protective coatings are used, durability is dependent on those coatings being maintained in good condition, reinforcing that coating performance is critical to achieving the required service life.

New Zealand Standards further require that surface coatings are applied as soon as practicable after installation so that the design moisture content of the timber is maintained.

To maintain durability and performance, including compliance with the moisture and durability requirements of the New Zealand Building Code (B2 Durability and E2 External Moisture), timber joinery must be fully protected from moisture ingress at all times by a suitable, continuous, film-forming protective coating system, which must be properly applied and maintained.

A complete and continuous coating system must be applied to all six faces of the joinery prior to exposure to weather to ensure a proper moisture seal and to reduce swelling, shrinkage, and moisture-related damage.

A minimum of two top coats of quality paint must be applied to all surfaces.

Particular attention must be given to:

· Tops and bottoms of doors and sashes

· End grain

· Glazing rebates

· Joints and junctions

· All cut, drilled, or scribed areas

· All areas where timber has been removed or exposed must be primed immediately.

The selection of coating system directly determines whether timber joinery can maintain its design moisture content in service and therefore comply with the durability requirements of the New Zealand Building Code.

The paint system should overlap onto the glass by approximately 2mm on the exterior surface to ensure a continuous seal at the glazing interface and to prevent moisture ingress at the junction between the joinery and glass.

Film-forming coating systems allow for this overlap to create a continuous seal between the joinery and glass. Penetrating oil and non-film-forming finishes do not form a surface film and cannot achieve this seal, leaving the junction between the glazing bead and glass more susceptible to moisture ingress.

If painting does not occur within six weeks of installation and exposure to weather, sanding and repriming may be required.

Joinery must not be left exposed to weather without a complete coating system. Temporary protection must be provided where coating is delayed.

Timber joinery left unpainted and exposed to the weather will cause changes in timber moisture content, leading to expansion and contraction, mould, rot, and potential damage to the joinery, and will void warranty.

GLAZING AND MOISTURE RISK

Insulating Glass Units (IGUs) rely on the long-term integrity of the edge seal to maintain performance and prevent moisture ingress. Industry standards (including AS/NZS 4666) require that IGUs are installed such that the edge seal is not subjected to prolonged contact with water or moisture. Timber joinery that is not fully sealed, including joinery finished with penetrating oils or non-film-forming coatings, can absorb and retain moisture within glazing rebates and beads. This can result in sustained moisture exposure at the IGU edge seal, increasing the risk of seal degradation, moisture ingress into the unit, and premature failure. Such conditions are inconsistent with glazing requirements and may void IGU manufacturer warranties.

The JMF glazing system and associated industry standards rely on a sealed and stable timber substrate, which cannot be achieved with non-film-forming coating systems.

DARK COLOURS AND HEAT EXPOSURE

The use of dark paint colours on exterior timber joinery can significantly increase surface temperatures when exposed to sunlight.

Paint colours are measured using Light Reflectance Value (LRV), where:

0 = black (maximum heat absorption)
100 = white (maximum light reflection)

Colours with a low LRV (typically below 45) absorb more solar radiation and can result in surface temperatures exceeding 60°C, even under moderate environmental conditions.

Timber is a hygroscopic material that absorbs and releases moisture in response to its environment. Elevated surface temperatures can accelerate this process and increase moisture movement within the timber.

Where one face of the joinery is exposed to greater heat or sunlight than the other, this can create uneven moisture conditions through the section of the timber, resulting in internal stresses.

These stresses may lead to:

distortion (bowing, cupping, or twisting)
movement across the grain
opening of joints
surface checking or minor splitting

This type of movement is a natural response of timber to environmental conditions and is not a manufacturing defect.

In some cases, this movement may reduce over time as the timber rebalances to its equilibrium moisture content.

To minimise the risk of excessive heat and movement:

Avoid the use of dark colours (typically LRV below 45) on exterior timber joinery
Where dark colours are used, increased movement and maintenance should be expected
Consider using lighter colours with higher LRV values to reduce heat absorption

SURFACE PREPARATION

All nail holes, fixing penetrations, hardware cut-outs, and surface defects must be:

Filled with an appropriate exterior-grade filler
Sanded smooth
Sealed and coated as part of the coating system

All exposed timber, including end grain and machined areas, must be sealed immediately.

All penetrations and fixings must be sealed at the time of installation to prevent moisture ingress into the timber.

Failure to properly prepare and seal surfaces may result in coating failure and subsequent timber movement.

CLEAR FINISHES

If clear sealing the joinery, a film-forming coating system specifically designed for exterior timber joinery is recommended, as it provides a higher level of protection against moisture ingress and reduces timber movement.

Penetrating oils and non-film-forming finishes are not considered sealing systems and do not provide the same level of protection against moisture uptake or dimensional movement.

Where oil-based or non-sealing finishes are used, increased moisture absorption and timber movement should be expected, and any resulting distortion, movement, performance issues, and double glazing failure will not be covered by warranty.

MOISTURE AND MOVEMENT

All timber joinery is manufactured from kiln-dried timber at a controlled moisture content suitable for stability at the time of manufacture.

Timber is a natural material and will respond to environmental conditions. Where joinery is exposed to changing conditions, dimensional movement may occur, including:

Expansion and contraction
Distortion or movement
Joint opening
Surface checking or cracking

These effects are natural characteristics of timber and are influenced by site conditions, coating systems, and maintenance practices. They are not manufacturing defects.

CARE AND MAINTENANCE

It is recognised trade practice that exterior timber joinery is designed for sheltered exterior use and should not be exposed to driving rain, direct sunlight, or extremes of humidity without appropriate protection.

A complete and continuous coating system must be maintained at all times on all edges and surfaces.

Routine maintenance includes:

Regular inspection and cleaning (minimum annually, more frequently in exposed environments)
Cleaning using mild detergent and water
Checking for:
- Coating breakdown
- Cracking, peeling, or wear
- Exposed timber or unsealed areas
Prompt repair of any coating damage
Recoating at the first signs of coating deterioration

Hardware and Fittings Maintenance

Hinges, rollers, tracks, and fittings must be kept clean and free of dust, debris, and contaminants to ensure smooth operation
Stainless steel components, including hinges and hardware, must be regularly cleaned to prevent surface staining or corrosion, particularly in coastal or exposed environments
Cleaning of stainless steel should be carried out in accordance with product manufacturer recommendations
Moving components should be checked periodically and maintained to ensure correct operation

Exposure Conditions

High exposure environments (including coastal locations, elevated sites, or north/west facing elevations) may require more frequent cleaning, maintenance, and recoating.

Please ensure coating supplier maintenance and recoating instructions are followed.

Failure to maintain coating systems, hardware, and surfaces will result in accelerated deterioration and may void warranty.

WARRANTY

We provide a warranty for all our timber joinery products against failure of materials and workmanship for 5 years from date of invoice.

For goods not manufactured by us, the warranty shall be the current warranty provided by the manufacturer of those goods.

Dando Doors and Windows does not provide a warranty for glazing. The glazing manufacturer/installer provides their own warranty.

Dando Doors and Windows will provide remedial works to correct defects arising from faulty materials or workmanship in the timber joinery.

This warranty does not extend to materials and/or services provided by subtrades, including glazing, glass, or hardware supply and installation.

All warranties for subtrade work must be obtained directly from those suppliers.

Remedial work carried out under this warranty does not include painting or finishing.

No liability shall arise unless a claim is made in writing within 30 days of the defect arising or being reasonably discoverable.

Copies of documentation showing purchase date must be included with any claim.

LIMITATION OF LIABILITY

This warranty is limited to repair or replacement of the faulty product at the company’s discretion and shall not exceed the original invoice value of the applicable joinery product.

No consequential losses will be considered.

WARRANTY EXCLUSIONS

No liability will be accepted where problems or damage occur from the following:

Incorrect installation or failure to install in accordance with relevant building codes and accepted trade practice.
The product has not been suitably painted and sealed to all faces, edges, end grain, glazing rebates, and penetrations prior to and during exposure to weather.
Failure to apply and maintain a continuous protective coating system in accordance with coating manufacturer specifications.
Use of penetrating oils or non-film-forming coating systems that do not provide a moisture seal.
Exposure to moisture, weather, or environmental conditions without adequate protection.
All nail holes, fixing penetrations, hardware cut-outs, and site modifications have not been filled, sealed, and coated.
The product has been subject to misuse, physical damage, or neglect.
Manufacturing standards and tolerances are not deemed defects.
Minor warping or twisting within accepted tolerances (up to 6mm).
Seasonal expansion or contraction due to environmental conditions.
Use of dark colours that increase heat absorption and movement.
Environmental conditions such as confined spaces, poor ventilation, or air conditioning.