Roof waterproofing

A roof that is not waterproofed (or is poorly waterproofed) can experience problems in the medium and long term, including leaks, mold growth, moisture, or structural damage. Damage to the roof can spread to the rest of the building, compromising its safety and health.

These problems can be avoided, both on newly constructed roofs and when renovating roofs and ceilings, by applying a high-performance liquid waterproofing system like Eagle’s Ultraflex system.

Why roof waterproofing is important

Proper waterproofing of roofs, ceilings, and flat roofs not only prevents structural and safety issues, but also:

It increases the durability of structural elements, thereby extending the building’s service life.
It enhances the building’s aesthetics and can increase its value.
It enables energy savings inside the building during the hottest months when membranes with heat-reflective properties are installed.
It improves indoor air quality by reducing the growth of mold and other potentially harmful substances.

Our high-performance liquid waterproofing system for roofs stands out because:

It is produced on-site, so it adapts perfectly to the roof’s shape, avoiding the common issues with prefabricated sheets.
It requires no prior primer, and its fully reinforced wet-on-wet application method, with no waiting time between coats, enables waterproofing projects to be completed more quickly and safely.
Once cured, it forms a fully watertight, elastic coating with no joints or overlaps, and is fully bonded to the substrate.
It’s a single-component, ready-to-use product, eliminating the most common errors associated with two-component systems.
It allows for on-site visual verification of proper consumption and application.

Applying Ultraflex waterproofing on various roof types

Our liquid waterproofing product can be applied to all types of roofs.

Ultraflex is a high-performance liquid polyurethane membrane certified for a service life exceeding 25 years and approved for both new construction and renovation projects. It is also suitable for waterproofing all types of roofs.

Flat roofs

These types of roofs have minimal slope, making them susceptible to water accumulation, which could lead to leaks. Our Ultraflex waterproofing system is ideal for this type of roof, as it resists standing water, is fully walkable, and is resistant to sunlight.

The Ultraflex liquid polyurethane membrane is a continuous membrane that adapts to any surface and shape, making it excellent for waterproofing complex roofs with multiple details. It ensures uniform, effective, and long-lasting protection.

How to waterproof a flat roof

When waterproofing rooftops, ceilings, or roofs with the Ultraflex system—Eagle’s liquid polyurethane membrane—as a general rule, follow these steps:

Prepare the surface to optimize the system’s durability

The entire surface must be thoroughly cleaned, removing dirt, mold, grease, oil, or any other contaminants that could compromise adhesion.

Before applying the liquid waterproofing material, treat expansion joints (if present), fill any cracks, tile joints, etc. In some cases, a general sanding of the surface or a pre-sealing on porous substrates may be recommended (at the discretion of the installer).

It is important to ensure that the surface to be waterproofed is firm, dry, and in good condition. If needed, Eagle offers a range of substrate preparation resins that can assist with these preliminary tasks (UltraPrime PRO, UltraPrime REG, UltraDry). Our technical department can provide more information on this subject.

Applying the membrane

Ultraflex is applied without prior priming thanks to its excellent compatibility and adhesion to various substrates (wood, metal, plastics, concrete, bituminous membranes—also known as asphalt felt—, PVC sheets, tiles, ceramics, fiber cement, brick, etc.).

The membrane is applied using the wet-on-wet method, which involves applying a double layer while wet, fully reinforced with Eagle Matting. This results in a membrane with a minimum thickness of 1.2 to 1.5 mm, typically achieved with a total consumption of 1.5 to 2 kg/m².

Apply the finish if necessary

When the membrane is exposed to sunlight or traffic (whether from people or vehicles), apply a thin layer of aliphatic polyurethane (Ultratop, Ultratop WR, or Cooltop, depending on the goal), optionally mixed with Ultraflex Grip if a non-slip finish is required.

The membrane allows for multiple finishes: installation of bonded pavements (ceramic, tile, etc.), floating pavements, etc. In these cases, applying this finishing layer will not be necessary.

Green roofs

For green roofs, also known as “green roofs,” even more careful waterproofing is required to prevent water and moisture from damaging the structure.

The Ultraflex membrane is approved for green roofs (EOTA, BBA) and is tested to be root-resistant.

Components of a waterproofed green roof

These types of green roofs have a slightly more complex structure than flat roofs. Broadly speaking, they are divided into:

Waterproofing layer: This layer is the primary barrier preventing water from penetrating the structure. It is essential to install this layer using a membrane that has been approved for this type of roof and that can withstand root puncture and constant contact with the highly humid environment of a green roof.

Drainage layer and filter layer: These are placed above the waterproofing and allow excess water to drain away, preventing it from pooling on the roof.

Substrate and vegetation: The substrate (a soil mix) is placed over the drainage and filtration layers, enabling vegetation to grow.

Waterproofing process for a green roof

When waterproofing a green roof with a liquid waterproofing system, it is essential to follow these steps:

Prepare the surface: As with flat roofs, proper cleaning and preparation are essential.
Install the waterproofing membrane: This layer must be continuous and cover the entire surface, as it will be the primary barrier against moisture.
Install the drainage layer and the filter layer: it is important to choose suitable materials to prevent damage.
Planting: Choose hardy, low-maintenance plants that are suited to the region’s climate.

A team with over 30 years of experience in roof waterproofing

At Eagle, we know this for certain: a roof—whether new or renovated—with a proven waterproofing system guarantees the present and future of any building.

That’s why hundreds of customers around the world rely on our waterproofing products for roofs and decks, both in new construction and roof renovations.

Related applications and keywords: roof waterproof sealant, flat roof waterproofing, flat roof waterproofing membrane and roof membrane waterproofing.

Waterproofing a roof

Waterproofing a dome-shaped roof

Bodegas Teneguía 2021
Renovation and waterproofing of dome-shaped roofs.

Projects completed with:

Roof waterproofing system, suitable for new construction and renovation.
Ideal for waterproofing rooftops, roofs, terraces, balconies, gutters, and drains.

Ultraflex is a single-component, moisture-reactive, cold-applied liquid polyurethane membrane that forms a continuous waterproof membrane, ideal for liquid waterproofing of roofs.

Roof waterproofing