Green Roof Water Retention

This type of water roof is called a water roof for rainwater retention.

Green roof water retention.

This means that the water leaves the roof as vapor. 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. Drainage and water retention elements with low medium or high retention capacity are components of the green roof system. The most critical role of the drainage layer is to provide an adequate flow of water off the roof during and after rainfall.

Later the sun comes out and the plants use the rainwater to evapotranspire. Yes every green roof absorbs and buffers water. The water only remains on the roof for a short period of time after rainfall. Water retention is really important in case of pitched roofs because their drying trend is more pronounced.

However a purple roof retains more water than any other green roof concept. The rainwater is drained off at a delayed pace using a narrower lower situated opening. We already had some common projects and results were reliable and spectacular. It should have good consistent drainage and aeration with a structure that enables it to hold water.

Rain falls onto a relatively dry green roof and the green roof absorbs the water usually in pore spaces. The secret of green roof water retention is green retention works like this. 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. Traditional soil is heavy and packs tight after repeated rains reducing water retention and aeration for plant roots.

Drainage green roof solutions offers many different drainage layer options depending on system goals regarding water retention. Green roof growing medium is composed of mineral aggregates and only a small amount of organic material. When the depth of water stored in the green roof growing media was treated as a variable roof storage was varied from 0 25 to 3 0 inches of storage using the 28 years of state college s daily rainfall data the results see figure 3 showed that the 3 5 inch green roof with 1 6 inches of water storage with a drainage layer and plants was an excellent choice. The water needs to be drained off to create sufficient storage capacity in time for the next rainfall.