​"We know more about the movement of celestial bodies than about the soil underfoot"  
Leonardo da Vinci

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Green Roofs 101 – Frequently Asked Questions:

 

  • What are their main benefits in our region?

Storm Water Management. Our storm water is not treated adding significant sediment and pollutants to the South Saskatchewan River. Green roofs soak it up, clean it up and greatly slow down any unused water. Often over 50% of annual rainfall is absorbed by a green roof and more if designed primarily for this purpose. Municipalities benefit as these roofs contribute to the capacity and longevity of hard (grey) storm water infrastructure which in so many cases has become frequently overburdened.


Reducing the 'heat island effect'. It can be 5 to 10 degrees hotter in dense and highly impermeable urban environments. On a hot day a conventional flat roof can soar to 70 degrees Celsius while a green roof can see regular daytime temperatures. Green roofs store water in the growing media and vegetation, and thus evapotranspiration plays a major role in reducing temperatures.

Reducing Waste. Conventional flat roofs here last only 15 to 20 years maximum. Green roofs protect the roof membrane from our climate and greatly buffer our numerous freeze/thaw/heat cycles. Studies show the life of the roof can be at least doubled or even tripled. Reroofing typically produces a large amount of waste so these amounts are cut in half or better.

Improved Air Quality. Elevated urban air temperatures lead to the formation of ground-level ozone (smog). Green roofs remove particulate matter from the air with their foliage and soil media. Plant evapotranspiration can reduce temperatures of rooftop air intake and cut air conditioning costs.

Energy Savings. Reduced roof temperatures can reduce heat conduction through a roof. Depending on design and winter vegetation, they can hold significantly more snow to help insulate as well.

  

  • Are green roofs 'proven' in our harsh prairie environment?

Yes. A small number of green roof have been implemented successfully in Saskatoon and Regina. Many more have been installed in cities such as Calgary, Edmonton and Winnipeg.

 

  • Do green roofs need maintenance?

Yes. Like any designed landscape, they all have some maintenance needs that vary depending on intent and design.

 

  • Do green roofs cost more?

Yes. Well...actually they can cost less over the life of the roof or facility! Depending on many factors, initial 'up front' capital costs can be significant however the financial, environmental and social benefits for the owner and the community can far outweigh these costs.

 

  • Why don't we see more green roofs here? What are the major barriers?

There are a number of common barriers, especially in relatively immature markets including:

  • Many owners, developers and designers are unfamiliar what is involved and the business case

  • Lack of local expertise, high costs of materials (e.g. importing soil medium and/or plants)

  • Many of the benefits accrue to the community and fewer directly to building owners

  • Lack of long term green roof data in our regional climate

  • Lack of financial incentives for owners and developers (e.g. municipal grants, tax incentives)​


  • At what point should you contact a Green Roof Professional (GRP)?

 Long before the design or even concept and certainly before the business case!!