Having proper drainage on a green roof is a critical aspect of the system.
Green shed roof drainage.
Green roof solutions offers many different drainage layer options depending on system goals regarding water retention.
Step 3 allow for drainage.
Make sure that the shed roof is fully waterproof.
The drainage also contributes to good aeration of the plant roots.
Make sure that the roof has a pitch that will enable drainage.
During a dry period the water stored can be reabsorbed by the vegetation layer above.
This roof was towards the shallow end of the spectrum and could perhaps have been a bit steeper.
The clay and silt content of materials used in a rock aggregate drainage layer should be 10 per cent by mass.
The slope of a green shed roof needs to be a balance between being too steep or too shallow.
Step 4 build a retaining frame.
The design of the different drainage layers allows for a portion of the stormwater to be retained above where the water is allowed to flow freely off of the roof.
Green roofs are made up of several layers typically a waterproof root barrier layer to protect the roof a drainage layer water retention mat then the growing medium and vegetation.
Pour a layer of gravel into the frame 2 3cm deep.
When saturated these layers can weigh in at more than 100kg per square metre or 20lbs per square foot.
The rock aggregate should also have a suitable ph and be low in soluble salts to ensure plant growth is not adversely affected.
Cut a piece of weed matting large enough to cover the roof and the inside of the frame.
The most critical role of the drainage layer is to provide an adequate flow of water off the roof during and after rainfall.
Whereas too steep means that the growing medium slides down the roof.
The drainage layer has an important role to play in the total system structure of a green roof.
Older green roofs often used a permeable layer of rock aggregate such as scoria or gravel for drainage.
This improves the drainage of the green roof which helps reduce soil erosion and aerate plants.
Lay it over the gravel and attach to the frame using tacks.
A shallow roof pitch wont allow water to drain away.
Green roofs can range from roof gardens with raised beds and pots to rolled out green carpets to shed roofs containing planting cells that are filled with soil or compost and planted up with low growing perennials and grasses.
Zurn is proud to introduce its green roofing drain product line specifically suited for the unique needs of a green roof installation.
