A concrete roof is constantly exposed to thermal movement, standing water risk, substrate cracks and long-term moisture pressure. Once the old waterproofing layer has aged, peeled, cracked or lost adhesion, simple surface patching may only provide temporary relief. For serious leakage or repeated seepage, a full removal method is often the safer option: remove the failed layer, repair and reinforce the substrate, then rebuild a new waterproofing system from the base up.
CKS recommends a two-product system for non-exposed concrete roof waterproofing after full removal: Primer FL1101 + Aquacoat 120. This system is designed to strengthen the porous substrate, improve interface bonding and form a seamless polyurethane waterproofing layer with high hydrostatic resistance.
The full removal method is suitable when the original roof waterproofing system is no longer stable enough to support a new coating. It is especially recommended when leakage has returned after multiple repairs or when the old waterproofing layer is hollow, cracked, powdery or poorly bonded to the substrate.
· Repeated roof leakage during heavy rain or after ponding water.
· Old coating or membrane is peeling, blistering, chalking or debonding.
· The concrete or cement mortar leveling layer is porous, weak or highly absorbent.
· The roof will be finished with screed, tiles or another protection layer, making it a non-exposed waterproofing area.
· A more reliable rebuilding system is preferred over short-term surface patching.
Primer FL1101 works as the substrate reinforcement and sealing layer. Aquacoat 120 works as the main waterproofing layer. Together, they help create a dense, firmly bonded and elastic waterproofing system for concrete roof areas that require a complete rebuild.
· Enhanced porous substrate adhesion.
· High hydrostatic resistance.
· Eco-friendly system positioning.
· Seamless waterproof film after application.
· Suitable for non-exposed concrete roof waterproofing works.
Primer FL1101 is a solvent-free, 100% solid epoxy primer. It provides excellent permeability, sealing and base-surface reinforcement properties. After coating and curing, it forms a dense and firmly bonded interface, preparing the substrate for the following waterproofing layer.
· Solvent-free: no pungent smell, environmentally friendly and healthier for application environments.
· Quick construction: short waiting time helps improve site efficiency.
· Good interface compatibility: compatible with various epoxy resin products and supports strong interface bonding.
· Good permeability: low viscosity allows use on dense surfaces and helps penetrate the substrate.
· Good sealing: suitable for porous and high-absorbency substrates.
Primer FL1101 can be used on epoxy mortar bases, concrete bases, cement mortar leveling layers and other suitable base materials. It is also suitable for porous, high-absorbency base surfaces. With an appropriate amount of graded aggregate, it can be used to prepare a mid-coat, leveling layer or repair mortar.
Aquacoat 120 is a high-performance, one-component, solvent-based polyurethane waterproof coating enhanced with graphene-based modifiers. It is ideal for non-exposed areas and is designed to provide superior durability and improved anti-seepage performance compared with standard polyurethane coatings.
· Ready to use: pre-packaged one-component format reduces mixing complexity and helps avoid quality problems caused by inaccurate mixing.
· Durable: stable performance with resistance to aging, acids, alkalis, fatigue and extreme temperatures.
· Eco-friendly: suitable for projects that require a more responsible waterproofing material choice.
· Easy installation: excellent leveling properties; after application, it reacts with moisture in the air to form a seamless, tough and highly elastic waterproof film.
· Versatile: can be combined with high-polymer membranes and self-adhesive modified bitumen waterproof membranes to create a comprehensive waterproofing system.
Aquacoat 120 is suitable for non-exposed waterproofing works, including bathroom floors, kitchen floors, balcony floors and roofs. For roof applications, it is especially suitable when the waterproofing layer will be protected by screed, tiles or another finish layer.
1. Substrate preparation: Remove the failed waterproofing layer, dust, loose material, oil stains and other contaminants. Repair cracks, honeycombs and weak areas. Ensure the substrate is sound, clean and suitable for primer application.
2. Apply one coat of Primer FL1101: Apply Primer FL1101 evenly to reinforce, seal and improve the bonding condition of the concrete substrate. Allow it to cure according to site conditions and product guidance.
3. Apply two coats of Aquacoat 120: Apply the first coat evenly to create the initial waterproofing layer. After the first coat reaches the recommended condition, apply the second coat in a cross direction to improve coverage and film continuity.
The key to roof waterproofing is not only the coating itself, but also the condition of the substrate and the bonding interface. Primer FL1101 helps seal and reinforce the concrete or cement mortar base, reducing the risk of weak interface bonding. Aquacoat 120 then forms a seamless, elastic waterproof film that helps resist water pressure and movement. This makes the system especially suitable for concrete roof waterproofing projects where the old layer has failed and the base needs to be rebuilt properly.
Can this system be used directly over an old waterproofing layer?
This article focuses on the full removal method. If the old waterproofing layer is peeling, hollow, cracked or unstable, it should be removed before rebuilding the system. Applying new waterproofing over an unstable layer may reduce bonding performance.
Is Aquacoat 120 suitable for exposed roofs?
Aquacoat 120 is recommended for non-exposed waterproofing works. For roof areas exposed to sunlight, traffic or long-term weathering, a suitable protection layer or an alternative exposed waterproofing system should be considered.
Why is primer necessary before applying the waterproof coating?
A concrete roof may be porous, weak or highly absorbent after old-layer removal. Primer FL1101 helps reinforce and seal the substrate and improves the bonding condition for the following waterproofing layer.
How many coats of Aquacoat 120 are recommended?
For this recommended solution, apply two coats of Aquacoat 120 after one coat of Primer FL1101. Always follow project requirements and product application guidance for film thickness, curing and inspection.
For concrete roof leakage caused by an aged or unstable waterproofing layer, the full removal method offers a more reliable route than repeated patching. By combining Primer FL1101 for substrate reinforcement and sealing with Aquacoat 120 for seamless polyurethane waterproofing, CKS provides a practical system for rebuilding non-exposed concrete roof waterproofing with stronger adhesion, higher hydrostatic resistance and long-term durability.
Need a reliable concrete roof waterproofing system? Contact CKS for product selection and application guidance.
