Flat roofs are a common solution in contemporary designs across the Costa Blanca and Valencia. Beyond their modern aesthetic, they offer valuable usable space such as terraces, green rooftops, or technical areas for daily use. However, like any surface exposed to the elements, they require flat roof waterproofing systems that are well-suited to the Mediterranean climate. In this article, we explore the most effective solutions to protect your roof from sun, rain, and moisture—without compromising on style or functionality.

The importance of a good waterproofing system in the mediterranean climate

While the region’s climate is generally mild, it does present specific challenges:

  • Intense UV exposure throughout the year

  • Short but heavy seasonal rainfall

  • Salty environments in coastal areas

  • Thermal fluctuations between day and night

Poorly executed waterproofing can lead to leaks, dampness, or structural damage. That’s why it’s essential to choose the right system based on how the roof will be used.

Most common types of waterproofing for flat roofs

Bituminous (asphalt) membranes

A traditional and cost-effective system. Installed using heat and usually protected with gravel or paving.

Advantages:

  • Good waterproofing performance

  • Easy to repair

Disadvantages:

  • Sensitive to UV rays if left unprotected

  • Less flexible with structural movements

Synthetic membranes (PVC and TPO)

A modern alternative, highly resistant to sunlight and long-lasting. Heat-welded to create a single seamless membrane.

Advantages:

  • Long lifespan

  • Quick and lightweight installation

Disadvantages:

  • Requires skilled installers

  • Higher cost

Liquid membranes (polyurethane)

Applied like a continuous waterproof paint, ideal for complex surfaces or areas with multiple junctions.

Advantages:

  • Seamless, highly adaptable

  • Visually appealing if left exposed

Disadvantages:

  • Application is sensitive to errors

  • Requires periodic maintenance in exposed areas

EPDM (synthetic rubber)

A highly elastic and durable material, widely used on technical roofs and areas with demanding requirements.

Advantages:

  • Chemical and thermal resistance

  • Long lifespan (up to 50 years)

Disadvantages:

  • Less attractive visual finish

  • Limited availability in some areas

Green or garden roofs: Sustainability at height

More and more clients are considering the option of transforming their roof into a green space. Garden roofs, also known as green roofs, offer thermal, acoustic, and ecological benefits.

Although they may seem incompatible with the dry Mediterranean climate, with proper planning they can work very well on the Costa Blanca.

Advantages of green roofs in warm climates

  • Lower interior temperatures in summer

  • Improved acoustic insulation

  • Support for urban biodiversity

  • Extended lifespan of the waterproofing by shielding it from the sun

In single-family homes, green roofs can be used as natural terraces, relaxing areas, or even small garden spaces.

Waterproofing systems for green roofs

Green roofs require specialised root-resistant waterproofing that can withstand vegetation penetration without compromising watertightness.

These systems typically combine several technical layers:

  • Root-resistant waterproof membrane (usually TPO, PVC, or bituminous sheets with specific additives)

  • Drainage layer to remove excess water

  • Geotextile filter to prevent blockages

  • Suitable growing medium for dry climates (sedums, aromatic plants, Mediterranean ground covers)

It is essential to design an efficient irrigation system, such as drip irrigation, to maintain water balance with minimal consumption.

Common mistakes to avoid on flat roofs

  • Insufficient slope: Even flat roofs must have a minimum gradient to allow water drainage

  • Poor detailing at junctions: Drains, parapets, and poorly sealed joints are critical weak points

  • Use of non-specialised materials: Some products lose effectiveness under constant sun exposure

  • Lack of maintenance: Regular cleaning prevents build-up of leaves or debris that could block drainage

What is the best system for the Costa Blanca?

There’s no single solution that fits every case. It depends on the intended use, budget, desired aesthetics, and the specific conditions of the location.

In general terms:

  • Technical or non-accessible roofs: Bituminous membranes or TPO with gravel

  • Exposed or accessible roofs: Liquid polyurethane or synthetic membranes with a ceramic finish

  • Green roofs: Multi-layer root-resistant systems adapted to dry climates

At La Quinta Fachada Arquitectura, we carefully analyse each roof to propose the most durable, safe, and visually integrated solution.

Final recommendations

  • Don’t cut corners on material quality or workmanship

  • Plan the final use of the roof from the design phase

  • Make sure the waterproofing system is compatible with the surface finish (ceramic, gravel, vegetation, etc.)

  • Carry out regular maintenance, especially after heavy rain

FAQs about waterproofing and green roofs

Can I install a green roof on any home?
Yes, as long as the structure is designed to support the additional load. A prior technical assessment is required.

What maintenance does a green roof need?
Minimal, if well designed: checking the irrigation system, controlling invasive plants, and cleaning drainage points.

Do green roofs provide better insulation than conventional ones?
Yes. They offer thermal insulation and help reduce the urban heat island effect.

Which option is the most durable?
Synthetic systems (TPO, EPDM) are highly durable, especially when protected with a surface finish.

Can systems be combined?
Absolutely. Some roofs include walkable, green, and technical zones, each with its own specific system.

Opinion

Flat roofs offer endless possibilities in Mediterranean homes—from viewing terraces to elevated gardens. Choosing the right waterproofing system is essential to ensure their durability and functionality.

At La Quinta Fachada Arquitectura, we combine design, technical expertise, and local knowledge to transform each roof into a usable, safe, and visually flawless space.