Roof waterproofing protects your home by creating a sealed protective layer across your roof that stops rainwater from penetrating inside. Without it, water slowly works its way through cracks and worn spots, and by the time you notice, the damage is already done.

The signs it’s needed are usually very telling – a musty smell that won’t go away, mould showing up in the attic or on nearby walls, water stains on your ceiling, and shingles that are curling or cracking. 

Now, cost-wise, you’re typically looking at somewhere between $1,000 and $10,000, but it depends on the size of your roof, its current condition, and what materials the job calls for. It’s not a small spend, but a proper waterproofing job can last up to 25 years, so you’re really paying once to protect your home for decades.

In this guide, we’ll walk you through what actually happens during a waterproofing job, the materials your contractor will likely bring up, and the questions worth asking before you hire anyone.

TL;DR

• A proper waterproofing job is a full process: inspection → cleaning → repairs → sealing weak points → applying waterproof layer → drainage check → final inspection + warranty.
• Common roof waterproofing solutions are membranes and coatings, which vary based on your roof type.
  • Metal roofs → liquid-applied membranes, acrylic coatings, polyurethane coatings
  • Flat concrete roofs → bitumen membranes, silicone coatings, cementitious coatings, polyurethane coatings
  • Tiled roofs → liquid-applied membranes, acrylic coatings 
  • Roofs with drainage issues → silicone coatings, polyurethane coatings, EPDM membranes
  • Large flat roofs → PVC/TPO sheets, EPDM membranes
• Always hire a licensed roof plumber who has experience, uses materials that suit your roof type, and offers a warranty on both materials and labour.

What’s Typically Included in a Roof-Waterproofing Service?

In Townsville, roof waterproofing can only be done by licensed roof plumbers or waterproofing contractors if the work is worth more than $3300, which involves the following: 

1. Roof Inspection

First, a technician comes to your place, climbs up on the roof, and takes a good look around. They check for:

• cracks, broken tiles, or holes
• damaged metal flashing (the metal pieces around chimneys, vents, or roof edges)
• signs of past leaks, such as water stains, mould, rust, or damp areas around weak spots in the roof structure
• whether water drains properly or pools up in certain areas

They try to figure out where water is coming in from. Once they find the problem spots, they snap some photos and explain to you what’s going on, so you can see the issue clearly before any work starts.

2. Roof Cleaning

Next, they give the roof a thorough cleaning; this is called ‘surface preparation’. They use high-pressure water to wash off dirt, moss, mould, bird droppings, and anything loose that stops the coating from sticking properly.

This step is very important because waterproof coatings only bond well to a clean surface. If there’s dust or moisture left behind, the coating won’t stick properly and could peel off later.

3. Small Repairs

Before applying any waterproofing, the expert checks for visible damage so the new layer can stick evenly to the surface. This includes:

• sealing small cracks
• replacing broken tiles or sheets
• tightening or swapping out rusty screws
• fixing damaged flashing

These repairs are necessary because if you just cover up damaged areas with waterproofing, the uneven, broken surface underneath can keep shifting, cracking, or getting worse over time. That can loosen or split your waterproof layer above it, letting water seep back in through the same weak spot.

4. Sealing the Weak Points

Now the plumber focuses on the spots where roof leaks happen most often. This includes pipe openings, skylights (glass windows on roofs that let in natural light), and roof edges. These areas fail more because they have joints, gaps, and openings through which water can easily slip.  

They seal these areas using waterproof sealants and strengthening materials that block water from getting underneath the roof surface.

5. Applying the Waterproof Layer

This is the main part of the service.

The expert spreads a liquid waterproof coating across the whole roof using rollers or spray tools. Once it dries, it turns into a flexible protective layer, like a rubber skin over the roof. This blocks rainwater and also protects the roof underneath from the sun, moisture, and weather damage.

The coating is applied in multiple layers. After the first coat dries fully, they add the next one on top. This creates a smooth, thicker, more durable waterproof barrier that’s less likely to crack or wear out.

6. Checking Drainage

After coating, the plumber checks the roof drainage system to make sure water can flow off the roof properly. If water stays sitting in one place for too long (ponding), it can slowly weaken even a new waterproof layer.

To prevent this, the professional examines the gutters, drains, downpipes, and the roof’s slope. If they find any problem, they may recommend clearing blockages, adjusting the roof slope, or improving drainage points so water can drain away properly instead of collecting on the roof.

7. Final Inspection and Clean-Up

Finally, the plumber inspects the roof one more time to make sure everything is sealed properly and evenly coated. They also clean up the site and remove any leftover dirt or material. 

After that, you get a warranty that if the waterproofing fails or starts leaking within a certain time because of poor workmanship or material failure, the team will come back and repair it at zero cost. 

Types of Roof Waterproofing Solutions You May Be Offered

The right solution depends on your roof material, slope, drainage, sun exposure, and how much movement or foot traffic the surface gets.

Most Common Types of Roof Waterproofing Solutions – At a Glance

Roof Type	Best Waterproofing Solution	Average Lifespan
Metal Roofs (Colorbond, steel)	Liquid-applied membranes, Acrylic coatings, PU coatings	10–15 years (liquid), 5–10 years (acrylic), 10–15 years (PU)
Flat Concrete Roofs	Torch-on bitumen membranes, Silicone coatings, Cementitious coatings, PU coatings	15–25 years (bitumen), 15–20 years (silicone), 8–12 years (cement), 10–15 years (PU)
Tiled Roofs	Liquid-applied membranes, Acrylic coatings	10–15 years (liquid), 5–10 years (acrylic)
Roofs with Drainage Problems	Silicone coatings, PU coatings, EPDM membranes	15–20 years (silicone), 10–15 years (PU), 25-30+ years (EPDM)
Large Flat Roofs	PVC or TPO sheet membranes, EPDM membranes	20–30 years (PVC/TPO), 25-30+ years (EPDM)

1. Membranes

A membrane is a thick, continuous, waterproof layer that covers the roof like a shield. It is stronger and lasts longer than coatings. 

Liquid-Applied Membranes

These are liquid waterproofing materials rolled or sprayed over the roof, where they dry into a seamless rubber-like layer. 

They are commonly used on metal and tiled roofs and complex roof shapes because the liquid spreads into cracks, joints, screw holes, and uneven areas to fully seal the surface. Most systems last around 10–15 years. 

Torch-On Bitumen Membranes

This membrane uses thick rolls of bitumen (a sticky, tar-like, waterproof material) heated with a gas torch, so they melt, fuse, and stick to the roof to create a thick, waterproof sheet.

They are mainly used on flat concrete roofs and balconies because they form a tough waterproof barrier and handle standing water well. These systems can last 15–25 years.

PVC and TPO Sheet Membranes

PVC (Polyvinyl Chloride) and TPO (Thermoplastic Polyolefin) are large, light-coloured (often white) waterproof sheets heat-welded together at the seams so water cannot pass through the joints.

They are commonly used on flat roofs, especially large residential and commercial roofs, because they reflect sunlight (because of their light colour), reduce roof heat, and handle harsh weather well. 

A properly maintained sheet membrane coating can last about 20–30 years. 

EPDM Membranes

EPDM (ethylene propylene diene monomer) is a synthetic rubber sheet that is sealed at the joints to form a continuous, watertight barrier – another good option for flat roofs. 

It is also flexible, so it does not crack when the roof expands or contracts with temperature changes.  

Most EPDM membranes last for 25 to 30+ years with proper maintenance. 

2. Coatings

Coatings are thinner waterproof layers that are applied over the roof to restore it or add extra protection against issues like standing water, heat, and coastal weather. 

Silicone Roof Coatings

Silicone is a liquid waterproof coating that dries into a smooth, seamless layer across the roof.

It is hydrophobic, meaning it repels water instead of absorbing it. Even if water sits on the roof for long periods, silicone does not soften or break down easily. This makes it ideal for flat roofs or roofs with drainage problems.

The average lifespan of a silicone waterproof coating is around 15–20 years. 

Polyurethane Coatings

Polyurethane (PU) is a thick, elastic, waterproof coating that bonds tightly to the roof surface.

Because the coating is thick and flexible, it blocks water and resists damage from movement and foot traffic. That is why it is used mainly for metal roofs, flat roofs, balconies, roof decks, walkways, and other roof areas where people regularly walk or maintenance work is done. 

Most polyurethane coatings last around 10–20 years.

Cementitious Coatings

Cementitious coatings, as the name suggests, are cement-based waterproof coatings. 

They are applied as a thick paste or slurry that hardens into a solid, rigid waterproof layer bonded to the roof surface, so they work best for concrete roofs and balconies. 

Cementitious waterproof coatings typically last between 8 and 12 years. 

Acrylic Coatings

Acrylic is a water-based waterproof coating that forms a thin protective layer that seals small surface gaps and reflects sunlight away from the roof to reduce heat build-up.

They work best on sloped metal and tiled roofs where water drains quickly because standing water can weaken the thin coating over time. Most acrylic systems last around 5–10 years.

3 Important Questions to Ask a Roofer Before Hiring

Once you’ve shortlisted a few licensed and insured roofers, ask them these questions to check the quality of their work and materials.

1. What waterproofing materials do you use, and why?

Ask what membranes, coatings, sealants, or flashing materials they plan to use and why they are suitable for your roof type.

Also, ask whether the product complies with AS 4654.1, the Australian Standard for external waterproofing systems.

2. Can you show previous work and provide progress photos?

Ask for photos of waterproofing jobs they have completed, especially of roofs similar to yours. 

They should be able to provide before-and-after or progress photos so you can confirm the repairs, preparation, and waterproofing were completed properly.

3. What warranties do you provide?

Ask what is covered, how long the warranty lasts, and whether it covers both materials and workmanship.

A material warranty covers defects in the waterproofing product, while a workmanship warranty covers installation or application mistakes.

Final Thoughts

If you notice signs like dark stains on ceilings, musty smells, or mould growth, it means moisture is already getting into your roof and can eventually lead to leaks, structural damage, and costly repairs if left untreated.

Because of this, always hire a licensed roof plumber for waterproofing work, as they have the training and qualifications to properly find and fix roof leaks. Also, check their experience, reviews, and warranties before hiring them. 

If you’re looking for reliable roof waterproofing services in Townsville, our team at 1touch Plumbing can help. Our licensed plumbers provide roof inspections, repairs, and waterproofing solutions designed to properly protect your roof from future water damage.

FAQs

Does home insurance cover the cost of roof waterproofing?

In most cases, home insurance does not cover the cost of installing or repairing roof waterproofing because insurers treat it as regular home maintenance.

However, insurance may cover the damage caused by a sudden roof leak, such as water damage to ceilings or walls, if the problem was unexpected and not caused by neglect or poor maintenance.

Damage caused by old age, worn waterproofing, or poor workmanship is excluded from cover, as they are considered maintenance and are your responsibility. 

How much does roof waterproofing cost in Townsville?

Professional roof waterproofing in Townsville costs around $40 to $100 per square metre. But the final price depends on:

• Roof size
• Roof condition
• Type of waterproofing used
• Repair work needed before coating

For example, if the roof has rust, cracks, or broken tiles, the cost will increase because these repairs must be completed before waterproofing starts.

Always ask for a quote that separates repair work from the waterproofing application so you can clearly see what you are paying for.

How long will a waterproofing treatment last?

Most roof waterproofing systems last between 5 and 25 years, but the exact lifespan depends on:

• The waterproofing material used
• The quality of installation
• Sun, rain, and weather exposure
• How well the roof is maintained

Basic coatings may last around 8–10 years, while high-quality membrane systems installed professionally can last 30 years or more.

When is the best time of year to waterproof a roof in Townsville?

The best time is during Townsville’s dry season from May to August. During these months, there is less rain and lower humidity, which gives the waterproofing enough time to dry and cure properly.