Indications For Roofing Contractors
In November of 2017, Denver voters passed a mandate that requires large buildings of at least 25,000 square feet incorporate either rooftop garden areas, solar energy, or both. It’s an effort to help the climate and reduce the urban “heat island” effect.
Heat island refers to the fact that temperatures are often a few degrees higher in cities than they are in their surrounding rural areas. This phenomenon happens when buildings replace natural greenery with cement, asphalt, etc., causing a loss of the evaporative cooling advantages of vegetation.
Because if this, air conditioning needs are higher which also increases greenhouse gas emissions. Due to this concern, Denverites chose to start a green trend moving forward.
According to one Denver resident who helped manage the campaign for the green roof mandate:
“People love the idea. We have all these flat roofs with all this space, and we’re not doing anything with them,” said Denver resident Brandon Rietheimer, the initiative’s campaign manager. “Why aren’t we putting solar or green vegetation up there? … We hear all the time that Denver is an environmentally friendly city, yet we rank 11th for air quality and third for heat islands.”
There are other cities who have passed similar measures, such as San Francisco, who passed the initiative in October of 2016. The supervisor who introduced the bill there, Scott Weiner, felt that many people have wondered why the roof space isn’t being used better.
City developers in San Francisco also support the green roof law because it offers an additional choice for an environment-friendly option.
Here is a video explaining more about the benefits of green roofs:
Cost of a Green Roof
With Denver’s green roof mandate, there is an increase in the cost of a commercial flat roof. The roof still requires most of the components it would without the greenery, so adding in the soil and plants along with the extra equipment needed to bring it all together makes a difference in price.
The cost of a flat roof is somewhere between $5 – $10 per square foot, where a green roof is at least $20 per square foot. On a 25,000 square foot roof, that is a significant cost increase.
Do the benefits outweigh the extra expense? This post explains more:
Costs for green roofs in the United States are estimated to average between $15 to $20 per square foot for all use types, i.e., high density residential, commercial, industrial etc.1 These costs include all aspects of green roof development, from the waterproofing membrane to soil substrate creation to planting. By far the highest costs associated with green roof creation are the soil substrate/growth medium and the plant components associated with it. Green roof retrofit projects may have increased cost associated with traffic and resource scheduling concerns as well as the on-site availability of equipment and materials. The cost of planting can also increase if plants are placed individually rather than pre-grown on vegetation mats.
Offsetting the initial capital and ongoing maintenance costs, green roofs provide a number of long-term cost savings. Rooftop vegetation moderates the temperature extremes of a roof surface and prevents it from being exposed to ultraviolet (UV) radiation and cold winds that could accelerate its break down. The result is an extended life span for the roof. A vegetated roof, on average, can be expected to prolong the service of the life of a conventional roof by at least 20 years (ZVG, 1996). When the savings associated with deferred maintenance and reduced energy consumption are taken into account, vegetated rooftops are comparable in cost to conventional roofs.
See the original post here: Green Roofs
It remains to be seen as to whether the Denver roofing contractors will embrace the idea, but they may not have much choice. Even though very few cities require green roofs on big commercial buildings, many offer incentives to take advantage of the trend.
There are exceptions to the rule, such as buildings less than 5 stories. This site provides more facts on the green roof initiative in Denver.
There are also do-it-yourself options for creating your own living roof if you have an existing flat roof that you would like to transform.