Commercial roofing in Sydney. Leaks fixed properly, and warranted.
We seal leaking metal and concrete commercial roofs and box gutters with a cold-applied liquid rubber membrane, for a fraction of what re-roofing costs. In 2025 we waterproofed 5,000 m² of roof at Optus Rosebery.
Free, no-obligation quote
Tell us about the roof and we'll give you a fixed price — usually within one business day.
- Free on-site assessment
- Fixed, transparent pricing
- Response within 1 business day
No obligation. Your details stay private.
Commercial roof repairs we do in Sydney
Most commercial roof leaks start in the same few places: screws, seams, penetrations and box gutters. We fix the cause, then seal the whole roof.
Commercial roof leak repair
We trace where the water gets in and seal it there. The ceiling stain is rarely right under the leak.
Metal roof restoration
We blast rusty, cracked or holed metal roofs clean, treat the rust and seal them with a seamless membrane.
Box gutter restoration
Box gutters are often where big roofs fail first. We seal the joints, seams and outlets as part of the membrane.
Concrete roof waterproofing
We repair cracks, joins and holes before the membrane goes on. A concrete roof needs different prep from a metal one.
NetZero reflective topcoat
A heat-reflective topcoat in a Colorbond colour that shields the membrane from UV and helps keep the building cooler.
Solar roof penetrations
Putting solar on the roof? We seal every fixing point before the panels go on.
A proven 4-stage system
Cold-applied. No open flame. Minimal disruption to tenants and operations.
Surface preparation
High-pressure water blast strips rust scale, contaminants and loose material for a clean substrate.
Liquid rubber membrane
Seamless cold-applied elastomeric layer over seams, penetrations, box gutters and detail areas.
Geo textile detailing
Reinforcement embedded at screws, joints and penetrations, which are the weak points where leaks start.
NetZero reflective topcoat
UV protection and heat reflection that weatherproofs the roof and cuts internal energy costs.
Commercial roofs we've sealed in Sydney and Queensland
Telco infrastructure, an airport, a refinery and a theme park. 25,000+ m² delivered across Australia.
Optus Rosebery
5,000 m²Brisbane Airport, Box Gutters
200 lin. mAMPOL Refinery, Brisbane
1,000 m²Coorparoo Education Precinct
3,400 m²Dreamworld
2,000 m²Mooloolaba (Coles)
5,500 m²Reference contacts available on request, subject to client confidentiality agreements.
Trusted by the people who own the roofs
Facility managers, retail groups and government, in their own words.
"RTT Sealant completed major roof waterproofing and restoration projects at our facilities in Brisbane and Townsville. The projects were a complete success — not only does the roof look brand new with its bright white solar reflective finish, there are no more leaks into the buildings. Given the size and difficulty of the applications, the hard-working RTT Sealant team was up to the task. We look forward to working with them on future projects."
"RTT Sealant has completed numerous waterproofing projects for Australia Fair Shopping Centre in Southport, including sealing concrete cracks and expansion joints in the car parks as well as box gutters and ridge capping on the roof. I found the application team to be very accommodating and professional, and their products have proved to be very effective and reliable."
"The roof at Coorparoo Education Precinct was in need of replacement, but due to the cost of removing the roof-mounted air-conditioning units it wasn't possible within budget. Your roof coating solution eliminated the need for removal, and all roof leaks were fixed after the product was installed. The team was a pleasure to deal with — always professional and safe. We are very pleased."
From rusted & leaking to sealed & reflective
Drag the slider to compare a roof before and after the RTT Sealant system.
After
BeforeThree simple steps to a roof that lasts
No paperwork to start. Just a conversation, and we take it from there.
Request a quote
Send us a few details by form or phone. Takes under a minute.
Free site assessment
We inspect the roof, scope the work, and give you a clear no-obligation quote.
We deliver the job
From surface prep through to warranty, you deal with one team that owns the whole job.
Get your free, no-obligation quote
Tell us about the roof. We'll arrange an assessment and give you a fixed price, usually within a few days.
Commercial roofing in Sydney: your questions
How much does commercial roof repair cost in Sydney?
It depends on the size of the roof, its condition and how much prep it needs, so we quote after a free site assessment. Pricing is line-itemed, and sealing a roof almost always costs well below re-roofing or paying for repeated reactive repairs.
Is it cheaper to seal a commercial roof than replace it?
On a structurally sound roof, yes. You keep the existing sheets and we seal them with a permanent membrane, so there's no strip-out and no need to move rooftop plant. At the Coorparoo Education Precinct, the air-conditioning units stayed where they were.
How long does it last?
It's a permanent membrane, not a patch, and we back it with a 10-year warranty (up to 20 years on PPA projects).
What causes leaks in metal roofs?
Usually the fixings and joins. Screws work loose, seams open up, rust eats through around fasteners, and box gutters crack at the joints. Our system reinforces those exact points with geo-textile before the membrane goes on.
Are you licensed and insured?
We hold Queensland QBCC Licence #1242527 (Class: Waterproofing) and carry $20M public liability cover on every site. Certificates are available on request.
Will the work shut down our building?
No. The system is cold-applied with no open flame, so you can keep trading while we work. We coordinate around tenants and can stage the job across the roof.
Do you work in Sydney?
Yes. We're based on the Gold Coast and take on commercial jobs in Sydney and across NSW. In 2025 we waterproofed 5,000 m² of roof at Optus Rosebery. Tell us where the building is and we'll confirm scheduling.