Airless Spray Guns for Roof Painting

Modern roof cladding is usually built to last but poor maintenance can see any roof material quickly degrade.

Recoating the roof is an ideal way to restore your roof’s stunning appearance, maintain its water proofing and effectiveness, and prevent roof degradation. And an airless spray gun is the perfect tool for roof painting projects of any type or size.

Airless spray guns work beautifully with all roof type claddings including:

• Metal
• Tile
• Concrete

Many common roof coatings are quite heavy with a high viscosity and require a high pressure for correct application.

This is where airless sprayers provide exceptional performance and cost effectiveness. Yes, you may be able to do it with a roller but it will take a great deal longer and the results may not be as pleasing or durable.

If you need to repaint or coat your roof then you need to do your homework.

The type of cladding and the material you intend to spray will help determine which is the ideal sprayer equipment to use.

So, let’s take a look at some common roof cladding types and coating materials and get some ideas on how to choose the best spray equipment for the job.

METAL ROOFS

The term metal roof actually covers a wide range of cladding materials.

You may be talking about unpainted galvanised steel panels such as standard ‘corrugated iron’ or your roof may have precoated Colorbond type cladding.

Metal tiles are another metal cladding that is popular on Australian homes.

There are other metal claddings too such as aluminium, stainless steel, or copper. But you should never need to spray either stainless steel or copper claddings.

Regardless of the cladding type, preparation of the roof before painting is essential for good results. And if the roof has been painted before this will also influence your choice of coating type.

Common coatings for metal roofs include:

• Oil-based coatings
• Acrylic coatings
• Elastomerics

Oil-based coatings have been around for a long time. They bond tightly to metal, offer rust protection, and prevent rust bleed.

Their disadvantages include; slow drying time, relative lack of colourfastness, and they may become brittle with age.

Oil- based coatings are usually recommended where a surface has been painted with oil-based paints before.

Water-based acrylic coatings are a newer product. They are usually more durable and offer better colourfastness and adhesion, faster drying times, and are generally more flexible on metal surfaces than oil-based paints.

Of course, one of the disadvantages of a rapid drying time is that you must be especially careful to avoid painting on hot surfaces as this may cause lapping marks and other quality issues.

Acrylics are especially recommended for metal cladding types that do not bond well with oil-based coatings.

Such coatings include galvanised metal and aluminium. Acrylics are also one of the few coatings that may work well when painting old asphalt coated surfaces.

Elastomerics are a specialised roofing product that form a thick rubbery membrane when dry.

Elastomerics are made from a blend of acrylic and elastomeric resins. They are much thicker than acrylics but offer extraordinary heat reflection properties.

Coating thickness and an even, consistent coverage are critical for a high quality finish with any roof coating.

Airless sprayers provide an exceptional degree of control over paint delivery. This means you can get a better more durable finish and significant cost savings thanks to the more efficient use of your paint.

It’s a good idea to avoid painting metal roofs when the roof surface temperature (not air temperature) exceeds 30 degrees Celsius.

If the roof gets too hot it can prevent the paint bonding properly with the metal. Quality problems may also occur when the roof surface falls below about 10 degrees Celsius.

TILE ROOFS

Metal, cement, terracotta and ceramic tiles can be painted. This is usually done where the original glaze has worn or excessive mould or lichen growth off has caused discolouration of the tile roof.

Tiles will generally retain their waterproof qualities unless they are cracked or damaged but airless spray equipment makes painting really quick and easy. The result is a beautifully revitalised roof.

Acrylic paints are perfect for tile roofs but as with any painting project you need to make sure you prepare the surface properly; cleaning moss, removing flaky, loose paint, and repairing or replacing any damaged tiles and pointing.

It’s important to ensure that you apply a consistent thickness of coating to any tile roof.

Airless sprayers and high-pressure guns are ideal for ensuring a rapid application with adequate coverage and depth to all tile surfaces.

The even pressurised spray ensures that all tile surfaces, including tile fronts, receive good coverage.

As with any airless spraying you need to check the paint manufacturer’s instructions for ideal tip size. This guarantees that you won’t get excessive overspray and will make the job faster and more cost effective.

CONCRETE ROOFS

Airless sprayers are perfect for spraying concrete roofing surfaces.

The pressurised spray fan ensures a solid even coverage and that any pores in the concrete are sealed. Acrylic paints designed for terracotta tiles are usually perfectly adequate for concrete tiles as well.

PAINT TYPES

Most major Australian paint manufacturers produce high quality paints and primers for a wide variety of surface types.

Look out for brands such as Dulux, Nutech, Resene, Superior Hi-Tech, Taubmans, Solacoat and ShieldCoat.

When looking for a premium quality paint make sure it meets the colour durability requirements required for APAS 0280 – Australian Paint Approvals Scheme. Inferior paints that don’t meet this standard are prone to colour fading and other quality issues. If rainwater is being harvested for drinking check the paint used is safe for potable water.

Oil based coatings are on the way out for most roofing applications especially if you are painting    previously unpainted surface.

However, they still have their uses if you are recoating a surface that has been previously painted with an oil-based paint.

Acrylics are ideal for most roofing types including tile, metal, and concrete.

Acrylics generally deliver excellent adhesion, durability, colour fastness, and rapid application. Acrylics also tend to be relatively easy to clean up and are rated low VOC.

Elastomerics are specialist roofing coatings that dry to form a thick rubbery membrane. Elastomerics offer exceptional weatherproofing and thermal insulation qualities.

High pressure airless sprayers are the perfect partner for the highly viscous nature of these coatings.

Two pack top coats (epoxy acrylic, or acrylic polyurethane) are highly viscous coatings that provide industrial strength anti corrosion and weathering protection.

These are often used in large scale commercial applications close to the coast. They do require large tips sizes and high pressure spraying equipment.

MAJOR BRANDS

Here are some of the offerings from two of the major paint manufacturers.

Their ranges also include primers suitable for both clean surfaces and badly damaged surfaces such as heavily oxidised metal or highly porous concrete.

DULUX

AcraTex is a range of acrylic membrane coatings that are ideal for concrete, terracotta tile and metal roofs.

Cool technology provides optimal thermal efficiencies and advanced cross polymer linking ensures this is one super tough coating. The AcraTex range also includes elastomeric top coats for masonry.

NuTECH

NXT Aquaguard is a waterproof membrane ideal for concrete and terracotta tiles, metal roofs and asphalt cladding.

It’s available in a rich array of 46 colours and is resistant to salt, fungi and algae attack. It’s heat reflective and low VOC. Due to its thick elastomeric makeup you’ll need to use a large tip size (20 to 30 thousandths).

NXT Cool Zone is ideal for metal and tile roofs and delivers real thermal insulation efficiency due to the infrared reflective pigments. This coating is highly resistant to chemicals, UV light and heat.

It is imperative that you follow the paint manufacturer’s recommendations for paint preparation, thinning and for choosing the appropriate tip size for spraying.

Choosing the Right Spray Painting Equipment

Airless sprayers that can deliver relatively a high paint flow per minute through a wider tip size and under pressure are ideal for all roof painting projects.

This is because of three factors:

1. Rapid application is important on external surfaces that heat up quickly under the sun
2. Many roof coatings are highly viscous and require a very consistent thick cover
3. Wider, more generous paint coverage across large roof areas minimises costly overruns

Ideally, you’ll want a minimum working pressure of at least 2,000 PSI and a paint flow of up to 5 litres per minute.

We supply a range of QTech sprayers, guns, and tips that are the ideal partners for all roof coating applications.

QTECH AIRLESS SPRAY PAINTERS

QTech QT290 Airless Sprayer

The QTech QT290 is a great choice for common medium-viscosity water or solvent based coatings and roof membrane spraying.

Specifications:

• Flow per minute: 2.9 ltrs/min
• Max tip size: 0.027″
• Maximum working pressure: 227 Bar | 3300 psi
• Motor: 1300 Watt
• Weight: 33kg
• Power supply: Single phase electric 240V
• Max Hose Length: Up to 60 metres with 523 spray tip

QTech QT550 Airless Sprayer

The QTech QT550 is a great choice for common high-viscosity water or solvent based coatings and roof membrane spraying.

Specifications:

• Flow per minute: 5.5 ltrs/min
• Max tip size: 0.031″
• Maximum working pressure: 227 Bar | 3300 psi
• Motor: 1500 Watt
• Weight: 59kg
• Power supply: Single phase electric 240V
• Max Hose Length: Up to 90 metres with 527 spray tip

QTech QT650 Airless Sprayer

The QTech QT650 is designed for spraying emulsions, top coats, intumescent, and common high-viscosity water or solvent based coatings.

Specifications:

• Flow per minute: 6.5 ltrs/min
• Max tip size: 0.037″
• Maximum working pressure: 227 Bar | 3300 psi
• Motor: 1800 Watt DC brushless
• Weight: 61kg
• Power supply: 240V
• Max Hose Length: Up to 90 metres with 531 spray tip

TRITECH AIRLESS SPRAY PAINTERS

T7 (Stand & Cart)

TriTech T7 is ideal for all roof projects using most common medium-viscosity water or solvent based coatings.

Specifications:

• Flow per minute: 2.91 ltrs/min
• Max tip size: 0.027″
• Maximum working pressure: 227 Bar | 3300 psi
• Motor: 1195 Watt
• Weight: 34.9kg
• Power supply: Single phase electric 240V

T9 (Hi Cart)

TriTech T9 is ideal for all roof projects using most common high-viscosity water or solvent based coatings.

Specifications:

• Flow per minute: 3.97 ltrs/min
• Max tip size: 0.031″
• Maximum working pressure: 227 Bar | 3300 psi
• Motor: 1565 Watt
• Weight: 44kg
• Power supply: Single phase electric 240V

AIRLESS SPRAY GUNS

The TriTech T360 and its bigger brother the TriTech T380 are superb all-round guns ideal for roofing coatings.

Specifications:

• T360— maximum working pressure of 250 bar / 3625 psi
• T380– maximum working pressure of 260 bar / 3800 psi

They are compatible with all leading brands of airless sprayers. And you’ll love the lightweight, beautifully balanced handle and trigger.

Choosing the Right Spray Tips

It’s critical to choose the right tip size for any painting project. Follow the paint manufacturer’s recommendations.

You can learn more about choosing tips sizes here but for most acrylic coatings you’ll probably be looking at a tip size of around 012 to 014 whereas thicker materials such as elastomeric will require tips between 025 and 039.

Getting it Right

Painting a roof is a serious investment in time and money so it’s worth doing properly the first time.

We’re here to help make sure you get the right equipment and the right advice for the perfect finish every time.