Green Roof

This article presents a brief study of green roof construction and benefits for modern buildings.

Key Benefits at a Glance

The core concept involves a layer of soil with growing grass or even small shrubs on the roof surface. For flat roofs, this creates an unexpected and valuable opportunity for residents or staff to enjoy leisure space. European experience includes green roofs hosting water features, golf greens, and sunbathing lawns—effectively increasing the building’s usable area.

The soil layer significantly enhances sound absorption, increases thermal resistance, and reduces heat loss during winter.

Beyond these benefits, green roofs offer a long service life with minimal maintenance, aside from watering plants during hot periods. They are ideal for moisture management and snow retention—soil naturally performs its function.

Classification of Inverted Roofs

Green roofs are categorized into two types depending on whether they are walkable or not.

If the roof is actively used—e.g., with garden landscaping, shrubs, or small trees—it is classified as an intensive green roof. These are expensive due to higher structural requirements for steel or concrete load-bearing elements. The more soil on the roof, the more expensive the building’s frame and walls become.

Installing an automated irrigation system becomes a major cost for owners, as manual watering is not feasible. Intensive green roofs are common on multi-story residential or office buildings, as well as on garages attached to private homes, serving as open terraces.

In contrast, extensive green roofs use vegetation purely as a decorative feature without functional load. No pedestrian zones or infrastructure are built on them, significantly reducing construction costs compared to intensive systems.

Plant Selection for Green Roofs

When planting on green roofs, ease of maintenance and long-term care must be prioritized. Naturally, low-maintenance, resilient plants thrive in extreme conditions are preferred. These include drought-tolerant lawns, rock roses, some bulbous plants, and sedums.

These plant types significantly reduce roof reflectivity, trap fine debris and dust, enhance architectural appeal, and ultimately improve quality of life and recreation.

Materials for Green Roof Installation

Green roofs are costly structures, so materials must meet stringent standards for reliability and durability. Any maintenance or replacement will be expensive.

Structurally, the roof system consists of the following layers (from outside to inside):

• Vegetative layer (grass, shrubs);
• Multilayer soil;
• Filters and separation layers;
• Drainage and water runoff system;
• Reservoirs for rainwater storage;
• Root protection layer;
• Thermal insulation;
• Hydro-insulation membrane.

An undeniable advantage of green roofs—like any inverted roof—is that the hydro-insulation membrane is placed beneath thermal insulation. This ensures it remains in a consistently positive temperature zone, greatly enhancing long-term durability. The most damaging process for waterproofing materials is the freeze-thaw cycle, which is minimized in this design.