Green roofs are becoming an increasingly common sight in housing estates and on commercial buildings and public facilities. No wonder – green roofs can create an attractive space for building occupants and an important element of pro-ecological urban architecture. That is why they are also a source of benefits for developers. Matizol developed a comprehensive Matizol Master GREEN ROOF system for the construction of rooftop gardens – a ready-made solution for flat roofs on new and upgraded buildings.
This eco-trend in architecture gains more and more popularity and recognition both among private investors and developers. Green roofs are created on apartment, office, public utility and commercial buildings. Flat roofs, typical for large-scale buildings, can be transformed to attractive spaces, especially in urban areas with high-density housing, and regain lost greenery areas. Roof gardens are an attractive solution for flat rooftops in brand new buildings and old building undergoing roof renovation.
Importance of rooftop gardens for investors, users and the ecosystem
Green roofs boost the prestige of the development. They increase the value of real estate (on average by 10 %, according to architects) and allow for more interesting solutions in space planning. Their users gain additional space for relaxation and recreation and have the opportunity to escape the hustle and bustle of the city without having to leave their homes. Roof gardens also bring an advantage in leasing commercial or residential space and attract tenants.
Planting greenery on roofs or terraces is one of the ways of adapting cities to the phenomenon of climate change as they counteract its negative effect. In addition, investing in rooftop gardens helps increase the quality of life and mitigate the effects of urbanization. What are the benefits of green roofs?
⦁ Improving air quality – Plants on green roofs produce oxygen in the photosynthesis process, reduce carbon footprint and clean the air of dust and fumes. Therefore, they are priceless in counteracting smog. 1 sqm of greenery can retain approx. 200 g of dust.
⦁ Reduction of the urban heat island phenomenon – The vegetation of the roof garden absorbs solar energy. In this way, it provides a cooling effect in an excessively heated city full of concrete and asphalt, with roofs covered with tar paper and sheet.
⦁ Improving the efficiency of solar panels installed on the roof – More and more solar panels converting solar energy into electricity are being installed across the World. However, in the view of experts in photovoltaics, remarkably high air temperature may reduce the efficiency of the panels. It is noticeable on hot summer days, when the air temperature is high, and the traditional roofing is an additional heat accumulator. Silicon contained in their panel modules may heat up too much, which causes the voltage drop in the modules and decrease in their efficiency.
⦁ Extension of the building floor area with a valuable biologically active space on the rooftop – According to the technical conditions, 50% of green roofs (i.e. flat roofs with a surface enabling natural vegetation of plants) are considered to be biologically active. The Local Development Plans (LDP) define the acceptable proportions between the biologically active area of the plot and the building area. The recovered biologically active surface on the roof allows for greater use of the area for development compared to buildings with a traditional roof.
⦁ Rainwater retention – greenery and drainage layers on the roof retain 50-80% of rainfall – Due to the retention function, the retained water evaporates into the atmosphere gradually, thus increasing air humidity and creating a favourable microclimate. This function also prevents flooding, relieving municipal sewage systems in critical situations. In addition, instead of letting water flow into the sea by rivers, this function can be used for irrigation. It also brings tangible financial benefits. The area of green roofs converted to a biologically active area with retention properties allows to reduce the fees for the so-called rain tax established by water law.
⦁ Improving the energy efficiency of the building due to very good insulation parameters of green roofs – This means that they provide good thermal insulation in winter, preventing heat loss through the ceiling, and protect against excessive heating of the rooms in summer, reducing the need for air conditioning, which brings real savings.
⦁ Noise reduction – due to the properties allowing for sound absorption – Overall, green roofs effectively reduce the level of noise coming from outside to the inside of the building.
⦁ Durability of technology – The structure of a green roof usually consists of a system of inverted layers (with waterproofing layer on the bottom and thermal insulation installed on it), as opposed to the traditional arrangement of flat roof layers. Such a system protects the waterproofing layer against mechanical damage and direct influence of external factors (UV radiation). Moreover, the temperature of the waterproofing layer remains constant so there is no risk of water vapor condensation, as a result of which the entire barrier remains energy stable.
Roof garden design in the Matizol GREEN ROOF system
Green roofs have a multi-layer structure. The type and number of layers are selected depending on the type of substrate and designed vegetation, loads, and the function of the building. Only the proper system design of a green roof determines its proper functioning. In order to meet customers’ expectations, Matizol specialists have developed a modern appropriately optimized green roof solution, having in regard individual components of the system. It is very convenient for green roof designers and contractors since its standardized arrangement of individual layers ensures the success of every roof garden project. They are provided with a ready-made system solution allowing to choose the type of green roof as well.
Extensive green roof in the Matizol GREEN ROOF system – light and easy to maintain
This type of green roof makes the building more attractive, and, in addition, it contributes to increase urban biologically active greenery resources, even if it is not directly used as a garden.
The creation of an extensive roof is quite easy, delivers a quick effect and does not require special maintenance in future. Extensive vegetation consists of low plants (mosses, sedum plants, perennials, herbs, grasses) – undemanding, resistant to periods of drought and frost, and capable of quick regeneration. Importantly, plants and vegetation layers of the system used for this type of roof are light (their weight in full saturation is from 120 kg/m2), so they cannot overload the roof structure.
Extensive green roofs are primarily recommended for single- and multi-family residential buildings and office buildings.
A sample extensive roof made in the traditional technology consists of extensive vegetation, GreenST Sedum substrate, GreenFiltr 100 filter fleece, GreenDrain drainage layer, GreenGeo Tex 300 protective layer, MATIZOL MASTER TOP GREEN ROOF PV S5.2 thermal bitumen membrane and underlay bitumen membrane, e.g. MATIZOL MASTER BASE PV S3.0 F/F. Then, there is a layer of EPS thermal insulation placed on the MATIZOL PRO VAP-ANTIRADON V + ALU S3.0 S/F vapor barrier, fixed with the KDT polyurethane foam.
A spectacular roof garden – an intensive green roof in the Matizol GREEN ROOF system
The intensive green roof allows the investor to create a real garden or even a park on the roof for all-year-round use. The intensive roof is made up of tall vegetation – flowers and shrubs – and elements of small garden architecture, e.g. pergolas, various types of seats, etc. Maintaining this type of roof is more demanding, because regular care, consisting in supplying plants with nutrients and water, is necessary but this effort brings measurable benefits in the form of a green enclave on the roof – perfect for relaxation and recreation.
Intensive green roofs are a perfect solution for commercial buildings (e.g. restaurants, hotels, holiday complexes), but they can be also created on public utility and apartment buildings.
The Matizol brand offers a comprehensive intensive roof system. Abizol R Dr primer is applied to the reinforced concrete ceiling, on which the MATIZOL PRO VAP-ANTIRADON V + ALU S3.0 S/F vapor barrier is placed. Then, using the KDT polyurethane foam, the EPS thermal insulation is fixed, and two bitumen membranes are attached to it: a base layer and an anti-root barrier ( MATIZOL MASTER TOP GREEN ROOF). Subsequently, a protective layer, a drainage and accumulation layer, a filter fleece and a substrate are installed, and finally, selected intensive vegetation is planted.
Summary
Green roofs are the eco-friendly solution that helps to improve the quality of life of residents, especially in large-city agglomerations. They allow for at least partial compensation of biologically active areas taken away by the development. Green roofs have also a positive impact on the building itself (e.g. it improves the energy balance) and its surroundings (improving air quality and reducing the effect of the urban heat island phenomenon). Roof gardens should become a common element of urban architecture. Creating green roofs should become an element of a conscious investment policy. The construction of green roofs is not only an economically profitable investment, but it can also reflect our concern for the climate and the natural environment. Such investments can be implemented with proven and reliable system technologies focused on setting up roof gardens.
