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Frequently Asked Questions

General FAQs

What are the new Building Code of Australia regulations in regard to Slips, trips and falls for windows?

Effective 1 May 2013, the BCA has introduced in Class 1, 2 & 3 in building and Class 9 for early childcare centres in regard to first and second storey homes, that windows in bedrooms have a restrictor to be used within 1700mm of the floor.

For windows where the fall height from floor to ground is 2 metres or greater, all openings within 1700mm of the floor shall be fitted with either a device to restrict the size of the opening or a screen with secure fittings. The device or screen must not allow a 125mm ball to pass through the window opening and resist an outward force of 250N (≈25kgs). The device or screen maybe removable, but if so must be a child resistant release mechanism,

The device or screen is removable, there shall be no window openings greater than125mm within 865mm of the floor. Also there shall be no horizontal elements between 150mm to 760mm above the floor which can facilitate climbing. All other window to follow the existing requirements.

What is the difference between STC and Rw ratings?

STC & Rw are laboratory test results and both mean the same as they relate to measuring sound, and are the terms used for acoustic ratings.

The STC abbreviation means Sound Transmission Class, it is the measurement of internal sound transmission, eg high frequencies. The number rating that is used to determine how much a material, eg glass window will resist sound travelling through the air (airborne sound transfer).

Rw abbreviation means weighted sound reduction index which uses airborne sound and is a scientific calculation, this is better for rating the attenuation of external low frequency noise, eg outside traffic travelling through a material, eg glass window.

This means a commercial window could have a STC rating of 30 but can be rated as 25 dB (decibel) for noise.

How do I maintain anodised aluminium?

To preserve the anodised aluminium finish over the years it is recommended regular cleaning.

Deterioration of the anodic oxidation coating can occur mainly as a result of dirt deposits and subsequent moisture, particularly when it is contaminated with sulphur compounds.

Cleaning should be carried out from monthly to six monthly intervals according to the degree of contamination from your local environment, whether it is atmospheric pollution or industrial pollution. You should aim to clean the anodised aluminium surface by removing grime deposits without causing any damage to the anodic oxidation coating.

Examples are recommendations only as pollution levels vary in areas:

• Rural & Tropical areas – mild – at least every 9 months

• Metropolitan areas – moderate – at least every 6 months

• Coastal areas – severe – at least every 3 months

• Areas within 5km of the marine coastal area or highly polluted industrial area – very severe – at least every month

Why do I need an Accredited Assessor’s report when building or renovating?

Under the Building Code of Australia, the Council of Australian Governments introduced key measures to help improve the energy efficiency of residential and commercial buildings across Australia. These new measures require that new buildings and renovations have a building energy assessments carried out.

There are different software packages used by Accredited Assessor depending on which state you are in.

Can you explain to me how to measure windows and doors to get a quote?

Our recommendation is that you get a tradesperson to measure, eg builder or carpenter so you have no issues with product not fitting correctly.

If you decide to measure yourself here are some tips to help you but we still recommend a professional tradesperson.

1) You need to evaluate how you are going to fit window or door.

2) Is the brickwork all in line or stepped back on the inside?

3) If brickwork in line you need to take at least three measurements across both horizontal and vertical faces, in case the brickwork varies, make a small allowance to have window fit the opening and this becomes your window size.

4) Product will be supplied with fins. Note: If full brick (double brick) consider having your windows de-finned, if using angles. If de-finning decide on size angles required and order enough to cover both inside and outside faces.

5) Responsibility of sizing is with the installer, so have your carpenter take the sizes as windows cannot be altered after the are made.

Can you explain some of the differences in the types of glass that are available for windows and doors?

There are many different types of glass available for windows and doors from standard float glass to double glazed units. Some typesof glass are used for different requirements, that is safety, energy efficiency, acoustics etc and what is used must comply with Australian Standard AS1288 Human Impact Safety.

Below is some of the different types are glass and what they are used for.

Float Glass: Clear glass used in windows to seal out the weather, and meet standard glazing requirements.

Obscure Glass: Used generally in bathrooms, toilets etc. to provide privacy, eg Spotswood, Satinlite.

Patterned Glass: Provides fashionable and functional alternatives for room dividers, door, side lites and feature areas.

Toughened Glass: Used in doors, or where safety is important, it is approximately 4 to 5 times stronger than float glass of equal thickness, making it far more resistant to impact. If broken, the toughened glass disintegrates into tiny, relatively harmless fragments, and as such is considered a safety glass for hazardous glazing locations.

Laminated Glass: Used in doors, or where safety is important, it consists of two or more sheets of glass with a plasticised polyvinyl butyl interlayer between to produce a permanent sandwich. Glass will crack but not break, and is approximately 2 – 2½ times stronger than float glass. Laminated glass is also used for its acoustic properties.

Tinted glass: Usually in Grey, Bronze or Green float, used to reduce summer heat coming into a room through the window.

Low E Glass: Used to reduce energy bills year round. It greatly reduces heat intrusion in summer and assists in keeping in the generated heat during winter. Special Low E coating on the glass means insulation from both heat and cold. In winter it keeps over a third more heat in a room. In summer it works the other way, to halve the sun‘s direct heat entering through the window, eg Comfortplus, Trend Low E.

Double glazed (insulated) glass units: Used to reduce energy bills year round, particularly in colder climates. Consists of two panes of glass separated by an aluminium spacer – profile and hermetically sealed around the periphery. Insulated glass units have a dual seal between the panes of glass and the spacer. The air space between the panes of glass provides the required thermal and sound insulation. For even better insulation they can be supplied as argon gas filled.

General terms used in regards to types of glass are:

• Transparent – Transmitting light, easily seen through.
• Obscure – Indistinct viewing not readily seen through.
• Opaque – Impenetrable to light, not transmitting light through.
• Translucent – Diffused light transmittance, not see through.

I have noticed the letters BAL appear when I am looking at bush fire rated windows. What does BAL stand for?

BAL means Bushfire Attack Level. There are six Bushfire Attack levels from low to extreme. Information on BAL assessments are contained in the Australian Standard AS3959-2009 Construction of Buildings in Bushfire Prone Areas for further information please refer to this standard.

The following shows the six bushfire attack levels and their predicted risk levels:

BAL-Low: This is insufficient risk to warrant specific construction requirements – Risk Level -Very low.

BAL-12.5: Ember attack- Risk Level – Low.

BAL-19: This is insufficient risk to warrant specific construction requirements – Risk Level – Moderate.

BAL-29: Increasing levels of ember attack and burning debris ignite by windborne embers together with radiant heat exposure between 12.5 and 19kW/m2 – Risk Level – High.

BAL-40: Increasing levels of ember attack and burning debris ignite by windborne embers together with radiant heat exposure between 29 and 40kW/m2 – Risk Level – Very High.

BAL-FZ: Direct exposure to flames from fire front in addition to radiant heat exposure of Extreme greater than 40kW/m2 and ember attack- Risk Level – Extreme.

For more information on Bushfire Attack Levels, please click here.

Why do my bifold doors have to have motif’s displayed across the glass? They look better without them.

Under AS1288-2006 Australian Standards Glass in Building any glazing that is capable of being mistaken for a doorway or opening (previously known as unimpeded path of travel) must have a motif displayed on the glass.

Motifs are required for the following:

• A glass doorway, eg sliding door, bifold door, hinged door must be fitted with Safety A glass or laminated glass

• An opening between inside and outside of a building, eg a full glass fixed panel

• Any glazing that can result in human impact cause any type of bodily harm to a human being

In other words, glazing that conforms to the following and shall not be considered to be capable of being mistaken for a doorway or opening:

1) The glass size width is less than or equal to 500mm;

2) The glass size height is less than or equal to 1000mm;

3) The lowest glass sightline is higher than 500mm above the floor level in residential buildings

4) Where a crash/chair rail, handrail or transom is provided and located with its upper edges not less than 700mm or its bottom edge not more than 1000mm above the floor level

Outside these following parameters glass panels will need to be fitted with a motif that is:

Permanently etched into the glass OR Self adhesive label that cannot be removed in a single action

This means motifs are placed on glass where,

1) The glass size width is more than 500mm; and

2) The glass size height is more than 1000mm;

3) The glass located within 700mm of the floor

My 18 year old timber double hung windows are not staying up. I have replaced the spiral tubes, tensioned both spirals and then screwed the base plate to the window on both sides?

There are different spiral sizes that take different weights. The spiral should have a coloured mark on it to indicate its weight range. You need to check to see if you replaced the old spiral with the same colour spiral, plus you need to check the length is the same size as the old spirals.

We have timber windows but find that rain is coming in through the bottom of the window, how do we stop the water. The windows are stained from previous leaks, is this a sign of not being treated?

If you are getting staining and leaking through the joints on the timber windows or if the windows have not been stained or painted, water will be absorbed through the end grain of the timber and will leak leaving marks.

You will need to dry the timber and sand back the marked areas and stain or paint the windows.

There are a number of reputable paint/stain suppliers in the market each offering a range of suitable solutions to finishing of joinery products

I have dry cement on my window frames and glass and would like to get it off without damage to aluminium powdercoating or glass. Can you please help?

Use plenty of water and let it soak onto the cement. Gradually lift off the cement from the frame or glass using a sponge or rag.

Keep reapplying water until it dissolve the cement particles and wiping it clean with a sponge or rag.

Do not use any abrasive objects.

How do I make a choice for windows and doors when choosing between aluminium and timber?

The most difficult part of any construction decisions for owners is the selection of windows and doors. In particular the base material to be used, that is aluminium or timber.

All projects will incur personal choices, difficult for others to recommend product.

The initial choices are:

Style of the house, aspect, and do you want slim line section profiles maximum glass area, look to aluminium, or heavy section profiles lean more to timber. Wanting slim line sections with the appearance of timber, why not select a wood grain finish in aluminium. Nothing though can match the warmth of a traditional timber look.

Do the windows need to complement the wall colour both internal and external?

Timber windows can have both internal and external faces painted in different light reflective colours. Aluminium windows come in only one colour, meaning a possible compromise on final colour.

If I select timber, how long will the paint finish last, paint companies state that paint or stain finishes should last minimum seven years before any re-painting required, dependant on the initial preparation being done in accordance with their recommendations. Aluminium windows come in powder coated and will last many more years with only minimal colour fade.

Note: Both product types however need to be cleaned periodically to remove contaminants from the atmosphere.

You are concerned about the added maintenance with timber. Apart from the re-finishing cost, hardware maintenance is similar to that of aluminium, both are tested for suitability and carry the same warranty. All products have a need for periodic maintenance to ensure long life wear.

Energy considerations, timber has a better initial thermal quality, although both aluminium and timber products can be improved using a wide range of Trend Thermashield glass options.

Pricing is comparative, the most critical decision to make is what suits the surrounding area and your project design, Cost is a short term consideration, and you have to live with the final choice for years to come.

What is NFRC and what has it got to do with WERS?

NFRC stands for the National Fenestration Rating Council which is an international rating organisation. NFRC ratings are internationally recognised and the Australian Building Code of Australia (BCA) has moved to utilising the NFRC ratings in the WERS program through the Australian Fenestration Rating Council (AFRC).

NFRC ratings are simulated through a computer program using advanced thermal simulation programs. WERS ratings utilises the NFRC ratings giving a full rating for the whole window system (includes frame, glass type, sealing system etc). The window/door products are certified by taking the u-value, SHGC and air infiltration to generate a star rating and percentage rating.

Window/Door manufacturers who have their products audited and are compliant will display the WERS logo or carry a WERS compliant label on their window/door products.

What is WERS?

WERS stands for Window Energy Rating Scheme and is managed by the Australian Window Association (AWA).

WERS was introduced in conjunction with the Australian Federal Government’s Australian Greenhouse Office and industry incentive as part of their commitment to improve Australia’s energy efficiency by reducing greenhouse gas emission into the environment.

My double hung windows do not slide up and down anymore but fall when I try to open them?

This means that the window spirals/balances need to be changed. When you replace them it is advisable that you open the window (top and bottom sashes) on a regular basis (eg fortnightly) to help them last longer.

My sliding doors and windows are 5 years old and do not slide properly. Why is this so and what do I need to do to prevent this happening?

It sounds like your sliding windows and doors rollers need to be changed due to wear and tear. Some tips on preventing the rollers from dragging is by vacuuming the sill of the windows and doors regularly getting rid of any dust, dirt and dead insects which cause a build up of grit in the rollers causing the rollers not to work properly.

On an annual basis clean tracks by wiping track with light machine oil (eg sewing machine oil) to assist with smoother operation.

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Values & Commitments

CDK are proud of our highly skilled workforce, exemplified by a number of our staff whose families have worked for us through the generations.

Our workforce is further complimented by our specialist sub-contractors who we have known and worked with for many years.

Bushfire Attack Levels

In the Australian Standards As 3959, they have classified different bushfire intensity levels that a home may experience during a bushfire.

These are referred to as Bushfire Attack Levels, or BAL’s for short.

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Cranbourne, Victoria,
Australia, 3977
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