Green Roof Water Retention

Figure 2 shows the daily rain and associated daily green roof runoff for 1993 in state college pa for a green roof having a maximum of 1 6 inches of water retention storage.

Green roof water retention.

Yes every green roof absorbs and buffers water. Green roofs are also known as vegetative or eco roofs. Geofabrics manufacture water retention and drainage boards designed specifically for living roofs. Drainage and water retention elements with low medium or high retention capacity are components of the green roof system.

However a purple roof retains more water than any other green roof concept. Although there are no precise definitions of them an extensive green roof has a shallow growing medium usually less than six inches with a modest roof load limited plant diversity minimal watering requirements and is often not accessible. The purple roof is the only concept that has been exposed to real life assembled testing in a professional setting. 0 01 0 17 at 2 roof pitch.

The most critical role of the drainage layer is to provide an adequate flow of water off the roof during and after rainfall. High level of reduction of of water discharge during high intensity rainfall whilst retaining good drainage even for large roof areas peak discharge. This means that the water leaves the roof as vapor. Our company offers consultancy and turnkey projects for green roof and terrace design landscape and long term maintenance in order to obtain the best results.

Suitable for blue roofs. System solutions with defined water retention. Fcp20 is a composite which is made of a cuspated sheet material with water retention cups to store water to promote healthy growth. Rain falls onto a relatively dry green roof and the green roof absorbs the water usually in pore spaces later the sun comes out and the plants use the rainwater to evapotranspire.

Discharge coefficient cs according to fll. Note that there was very little if any runoff during the may 1 to sept 30 growing season. However retention is not always effective as it fills up the entire empty storage space in green roofs and then takes time to dry out and make room for new rainwater. Green roofs typically provide stormwater retention as they capture water preventing water from draining and then allow the water to evaporate only through evapotranspiraton processes.

Such an extensive green roof will have a water retention capacity up to 44 l m and a surface weight in water saturated condition about 130 kg m. We need to think differently about the main purpose of a green roof. Manufacturers whose materials we use for landscape works are well known all over the world. The secret of green roof water retention is green.

Green roof solutions offers many different drainage layer options depending on system goals regarding water retention. They fall into three main categories extensive intensive and semi intensive.