icf and greenroofQuadblocks and Litedeck

Insulated concrete roof/floor/deck form systems (like the Fortruss system)provides the ultimate roof. The concrete wall and steel reinforcement transitions to the concrete roof deck and beam system. This style of building is the next step for Nutmeg Homes. A roof that is super insulated, indestructible, and can be used as a giant deck! Turning this roof system in to the ultimate eco roof a green roof is easy. Although green roofs are being strongly -promoted required by some provincial and municipal governments in commercial buildings, residential green roofs appear to be banned by the BC New Home Warrantee Office (HPO). Nutmeg Homes is working with several specialists, ICF suppliers and green roof drain system companies to build the first warranteed ICF residential green roof in BC. Green roofs should be called ‘living roofs’ or ‘vegetative roofs’ as the are not always green in colour.

Environmental benefits

6 acres 6 acres of Green

Green roofs are used to:

Financial benefits

 This could be our future!

Types

green roof layersAn extensive roof

Green roofs can be categorized as intensive, “semi-intensive”, or extensive, depending on the depth of planting medium and the amount of maintenance they need. Traditional roof gardens, which require a reasonable depth of soil to grow large plants or conventional lawns, are considered “intensive” because they are labour-intensive, requiring irrigation, feeding and other maintenance. Intensive roofs are more park-like with easy access and may include anything from kitchen herbs to shrubs and small trees. “Extensive” green roofs, by contrast, are designed to be virtually self-sustaining and should require only a minimum of maintenance, perhaps a once-yearly weeding or an application of slow-release fertiliser to boost growth. Extensive roofs are usually only accessed for maintenance. They can be established on a very thin layer of “soil” (most use specially formulated composts): even a thin layer of rockwool laid directly onto a watertight roof can support a planting of Sedum species and mosses.

Another important distinction is between pitched green roofs and flat green roofs. Pitched sod roofs, a traditional feature of many Scandinavian buildings, tend to be of a simpler design than flat green roofs. This is because the pitch of the roof reduces the risk of water penetrating through the roof structure, allowing the use of fewer waterproofing and drainage layers.

Disadvantages

green roofHoney bee Heaven

The main disadvantage of green roofs is the higher initial cost. Some types of green roofs do have more demanding structural standards especially in seismic regions of the world. Some existing buildings cannot be retrofitted with certain kinds of green roof because of the weight load of the substrate and vegetation exceeds permitted static loading. Depending on what kind of green roof it is, the maintenance costs could be higher, but some types of green roof have little or no ongoing cost. Some kinds of green roofs also place higher demands on the waterproofing system of the structure both because water is retained on the roof and due to the possibility of roots penetrating the waterproof membrane. However, a sedum covering doesn’t need water to be retained on the roof as these plants can tolerate long periods without rainfall, so a drainage layer will combat this particular problem. Moreover, properly designed and installed systems include root barriers. It is true that installing adequate waterproofing systems and root barriers can increase the initial cost of the roof, however, due to the fact that a green roof protects the waterproofing membrane from the elements, particularly UV light, the life expectancy of the membranes is doubled or even tripled, leading to recovered initial cost differentials.

Canada

grassy meadowThe largest green roof in Canada

The city of Toronto approved a by-law in May 2009, mandating green roofs on residential and industrial buildings. There is criticism from Green Roofs for Healthy Cities that the new laws are not stringent enough, since they will only apply to residential building that are a minimum of six storeys high. By 31 January 2011, industrial buildings will be required to render 10% or 2,000m² of their roofs green. In 2008, the Vancouver Convention Center installed a six-acre living roof of indigenous plants and grasses on its West building, making it the largest green roof in Canada.


Back to house building – there are lots of openings in a wall, doors, windows, hose bibs etc, and that what we’ll look at next …


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Chapter Three – Part 1 – Openings