LIVING ENJOYMENT ~ Creates green area, sound proofing, keeps building cooler in winter and warmer in summer, increases property value, enhances lifestyle.

STRUCTURAL ~ extends waterproofing life, adds to fire protection, enhances wind uplift restraint
protects against ~ UV, temperature extremes, expansion and contraction, hail, rainwater overflow in storms, encrustation.

ENVIRONMENTAL ~ improves microclimate, air quality by binding/filtering dust, reduces impact of urban growth, retains moisture in dryer seasons, provides a home for birds and plants

DRAINAGE ~ reduces drain overflow likelihood and pressure on streams and reservoirs. Reduces the impact of hard surfaces and land sealing.

EXTENSIVE Green Roofs can be designed to achieve:-

LOW MAINTENANCE created by laying down a:-

very low depth of organic matter (greater than 20mm) with a dry weight of 25 to 40   kg/sq m this will allow moss and sedum to grow to a height of less than 10 cms. 

low depth of organic matter (greater than 70mm) with a dry weight of 40 to 120 kg/sq m this will allow sedum, grass and small root plants to grow to a height of less than 50 cms. 

MODERATE MAINTENANCE created by laying down a:-

depth of organic matter (greater than 150mm) with a dry weight of greater than 120 kg/sq m this will allow grass and perennial plants to grow to a height of greater than 50 cms.

INTENSIVE Green Roofs while of higher maintenance can be designed to achieve:-

GREATER VARIETY OF PLANTS ~ lawns, flower beds and small bushes ~ created by laying down a:-

  depth of organic matter 200 to 300mm with a dry weight of greater than 175 kg/sq m
  depth of organic matter greater than 300mm with a dry weight of greater than 300 kg/sq m
  depth of organic matter greater than 400mm with a dry weight of greater than 350 kg/sq m

TECHNICAL ASPECTS

Watering
Watering is necessary in periods of drought and more frequently with non succulent plants. Sedum tends to be more tolerant than many plants. An integral irrigation system is often a worth while investment to minimise watering maintenance .

Installation
Sedum rolls which are relatively heavy (ie two person installation is recommended) need to be laid out flat until planted up. The roof surface should be crease free and clean. Treated timber c50 x 25mm should be fixed around the perimeter without damage to the integrity of the waterproof membrane. Provision needs to be made for drainage passed the timber retainer. If the roof has an apex, it is best covered with a moisture retention sheet 500 to 700 mm broad to reduce the tendency to dry out. The perimeter can now be tidied up.
The sedum mat can be laid over the apex and then the perimeter so if cutting is necessary then the smaller, more vulnerable pieces are in the middle. Each side of each roll needs to be nestled up closely to its neighbour and made compact. A check needs to be made to ensure no rolls have moved down the slope under gravity. To assist the sedum in settling into its new location, water abundantly and scatter an inorganic nitrogen, phosphorus, potassium fertiliser.

Maintenance ~ The fertiliser should be a slow release, low nitrogen granular fertiliser applied in the spring. Overfeeding should be avoided not only to save money but fertilisers in watercourses may cause pollution. Sedum dislike sodden roots so ensure they are well drained. Aphids (green fly) are attracted to the succulent leaves of sedum fortunately causing little harm although unattractive to see. Most sprays are not suitable for sedums as the burn and mark the leaves ~ if the spray is suitable for blackcurrants, it should be satisfactory for sedum as they are related plants. Alternatively, an infusion (tea) made of chopped green leaves of the herb Tansy (tanacetum vulgare) makes a good organic insecticide for aphids.