Why maintain your exterior paint system?
How often do I need to paint or stain my home?
What Colour should I paint my house?
Can I paint my older home in a dark colour?
Are there any limitations on colour selection?
What is Light Reflectance Value?
How does Cool Colour technology work?
How to prepare weatherboards in good condition?
How to prepare weatherboards in poor condition?
What is an elastomeric paint?
Does Allied Exteriors use elastomeric paints?
How can you tell whether existing paint coating(s) are sound?
How long before paint coatings start to fail?
Why maintain my exterior paint system?
Like washing your car, cleaning your house will help it maintain its good looks and weathertightness for longer.
Airborne contaminants, including salt deposits which settle on your paint film, may attack the paint surface and cause premature breakdown. Moss and lichen can also penetrate the surface of the paint film, damaging its integrity and reducing the useful life of the paint film, while mould growth can destroy the chemical entity of the resin system that holds the paint system together. The presence of moss, mould and lichen will hold moisture on the surface longer, promoting further growth of these organisms and increasing the risk of damage to the coating. Removal of moss, lichen and other contaminants using the appropriate washing procedure will increase the life of the coating and maintain the aesthetic properties of the paint finish.
Annual washing of your home will help maintain the fresh appearance of your paintwork. We recommend using Resene Paint Prep and Housewash diluted as recommended with water. Apply the diluted solution via a garden spray unit and softly agitate the surface with a soft broom. Wash off thoroughly with fresh water. [Top]
How often do I need to paint or stain my home?
As a general rule, you should expect to recoat your house every 7-10 years for plaster cladding systems, every 10-12 years for painted weatherboard cladding systems and every 2-3 years for stained timber surfaces. [Top]
What colour should I paint my house?
Colour selection can be a difficult choice, especially where a complete change in colour scheme is being contemplated. We often get asked for advice and sometime to choose colours and colour schemes for our clients.
We assist our clients with colour selection by offering a free colour consultancy with a profession colour consultant. Furthermore, we are able to provide colour swatches and sample brush-outs to see how the colour looks on the wall surface.
Colour comes down to personal preference and whilst we can assist the selection process, ultimately, our clients must specify colour to be used. [Top]
Can I paint my older home in a dark colour?
Yes, you can. But there are risks attached.
A common catalyst for inter-coat adhesion failure is changing from a light-coloured paint to a darker coloured paint. The increased heat generated by darker coloured coatings can be the tipping point causing inter-coat adhesion failure. We do not recommend dark coloured coatings over aged substrates and existing coatings as the heat generated will shorten the service life of the underlying coatings and expedite paint failure issues. [Top]
Are there any limitations on colour selection?
Yes there are, for exterior cladding systems.
If you are painting the exterior of your home, consideration must be given to what substrate is being painted (i.e. timber weatherboards, fibre cement weatherboards, plaster cladding system, precast concrete etc).
Timber weatherboard and plaster cladding systems have colour limitations based on the LRV (“Light Reflectance Value”) of paint colours. Some of the general limitations are included in the Building Code E2/AS1 document but most cladding system manufacturers have specified minimum LRV requirements for their cladding systems.
In simple terms, choosing a colour which is too dark (i.e. below the specified minimum LRV requirement) for a particular cladding system increases the risk of damage to the cladding through warping and splitting of weatherboards or cracking and delamination of plaster cladding systems.
Allied Exteriors’ specialist area of trade is the installation of new weatherboard and plaster cladding systems (we don’t only paint them) and we have specialist expertise and knowledge in this areas. We assist our clients ensuring the right products are used to specification so that future problems are avoided and our clients do not void their cladding warranties. [Top]
What is Light Reflectance Value?
Reflectance is the proportion of light that a surface reflects compared to the amount of light that falls on the surface.
The light reflectance value of an individual colour indicates the amount of light and heat that individual colour will reflect. Black has a light reflectance value of zero and absorbs almost all light and heat (think of black leather car seats heating up in the sun). White has a light reflectance value of nearly 100 and will keep a building light and cool. All colours fit between these two extremes.
A colour with a light reflectance value of 80 (which means it reflects 80% of the light that falls on it) will reflect more light than a colour with a light reflectance value of 20 (which means it reflects 20% of the light that falls on it).
The different LRV requirements for each type of cladding relate to ability of the substrate to absorb and dissipate heat. The mass and material composition of the substrate influence their ability in this regard. For example, a solid concrete wall has a greater ability to dissipate heat away from a plaster coating than a Fibre Cement substrate. Accordingly, solid concrete has a lower LRV limitation which means greater flexibility in colour selection.
In recent years, ‘Cool Colour’ technology has been adopted by some of the paint manufacturers with a view to providing more flexibility in colour selection. Cool Colour technology is designed to reflect more of the sun’s energy than standard colours and thereby help to reduce heat build-up in the substrate.
We often get asked if we can use Cool Colour paint so a dark colour can be used on a cladding system. In such circumstances, we look at the particular project (i.e. what colour is being proposed (i.e. how dark is it), what is the substrate and is the painted wall surface exposed to high levels of sunlight?). We then discuss the request with the cladding system manufacturer to what is achievable. [Top]
How does Cool Colour technology work?
Dark colours on exposed areas such as roofing and wall cladding are suntraps soaking in the sun's rays placing relentless thermal stress on the coating and the substrate. All dark colours absorb a lot of light. They also absorb a lot of heat from the infrared rays of the sun causing significant temperature build up on the surface. White and light coloured paints reflect both light and heat and therefore are less affected by the sun’s rays.
Cool Colour technology allows darker colours to absorb light so they look the same but simultaneously reflect a large proportion of the infrared heat. The technology works by reflecting energy in the near and far infrared region of the spectrum even though they absorb strongly in the visible region. A secondary benefit is that the reduced stress on the coating and substrate will help to increase the expected lifetime of each compared to a standard version of the same colour.
Cool Colour technology will not resolve all issues related to heat, but will help to reduce the impact of dark colour selection. Practical and cladding warranty requirements still need to be taken into account when using Cool Colour paints. [Top]
How to prepare and paint existing weatherboards in good condition?
If the existing paint coating on the weatherboards is in reasonable condition, standard preparation is typically all that is required.
This includes the following steps:-
1) Wash the building to remove contaminants
2) Sanding and/or scrap any loose or delaminating paint
3) Spot prime the prepared areas
4) Fill any holes or gaps and lightly sand
5) Prime the sanded areas again
6) Apply two coats of Premium Acrylic Paint
At Allied Exteriors, we only use premium quality paints from Resene, Dulux or Wattyl (we don’t use cheaper trade-line or imported products). The cost of the paint is a relatively small portion of the overall contract price and we want our clients to know they are getting a high quality and durable paint job.
Quality starts with sound preparation and is completed by correct application of the best quality materials. [Top]
How to prepare and paint existing weatherboards in poor condition?
If the existing paint coating on the weatherboards is in poor condition, standard preparation will not be enough. All poorly adhering, flaking, peeling and bubbling pant must be removed to provide a sound substrate for the new paint coating system.
Our process includes the following steps:-
1) Apply an moss and mould killer (where required)
2) Wash the building to remove contaminants
3) Mechanically or chemically remove the failing paint
4) Sand all exposed bare timber areas
5) Apply a wood primer to the sanded areas
6) Fill any holes or gaps and lightly sand
7) Prime the sanded areas again
8) Apply two coats of Premium Acrylic Paint
Stripping existing paint coat systems is a time consuming labour intensive process and will add significant cost to the project (typically doubles the cost of a standard paint job if all existing paint is removed).
There are various methods for removing paint ranging from mechanical removal to using chemical strippers such as Resene Sea to Sky. Some chemical strippers work better than others and some are more toxic than others. Mechanical stripping methods bring an increased risk of damaging the weatherboards by gouging them or leaving circular marks in the timber. This can be remedied by sanding and using a filler primer but does add cost to the process.
Removing a failing paint coating is the only way to ensure against problems with the new coating system. We can discuss with you whether mechanical stripping or chemical stripping is the better option for your project. [Top]
What is an elastomeric paint coating?
Elastomeric coatings have higher volume solids than conventional paints and are applied with a much higher dry film thickness (DFT) than conventional paints. They have greater elongation capabilities and do not penetrate the substrate to the same degree as a conventional paint. Instead, elastomeric paint forms a membrane coating that sits on the substrate and will bridge minor fractures without breaching the paint coating. This is why they are considered very good waterproofing paints. Ensuring the coating system is applied to the correct DFT is critical to the performance of an elastomeric coating. At Allied Exteriors we calculate the quantity of paint required for each project to ensure the correct DFT is achieved. [Top]
Does Allied Exteriors use Elastomeric Paints?
Yes we do. Primarily, we use Resene X200 Waterproofing Paint, Dulux 201 Elastomeric and StoLastic Paint for our new cladding installations and repainting of existing homes. Over the years, we have used thousands of buckets of these products without any problems. Elastomeric paint systems require care and attention during the application process to ensure the finished product looks great and performs to specification. Our team is well experienced in the application of these products and has the expertise to ensure our clients get a top quality paint system that will stand the test of time. [Top]
How can you tell whether existing paint coating(s) are sound?
Although a previously painted surface may visually appear sound, it is often not until the surface is repainted that the instability of the underlying coatings becomes apparent.
It is not possible to know when an existing paint coating that appears sound is going to fail as there are too many variables involved (i.e. substrate quality, type of primers and paints previously used, preparation between coatings etc).
We can undertake a basic adhesion test but such tests are a very blunt instrument. There is always risk involved in painting over existing aged paint coatings. [Top]
How long before paint coatings start to fail?
All coatings (including paints, sealers and glazes) have a finite life and will fail eventually. With each recoating, the number of underlying coatings builds up and the risk of one of the previous coatings failing increases.
In our experience, inter-coat adhesion failure occurs infrequently on substrates less than 20 years old (assuming the correct preparation between repaints has been done). The risk increases with the presence of lead primers, enamel coatings, the number and age of coatings and when a change is made to a darker paint colour.
Modern acrylic coatings have good adhesion to clean, sound existing coatings and usually any failure will occur between two of the older coatings. [Top]