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Green Roofs: What You Need to Know About This Eco-Friendly Roofing Option

Jul 28th, 2020 // Roof Installation

A green roof provides many advantages to personal and public spaces. However, installing one is not as simple as planting greenery on top of your home or business. Intricate systems must be properly installed to keep things functioning effectively and efficiently, while also protecting the structure below the roof. When done correctly, green roofs are a beautiful and sustainable way to create positive environmental impact. 

What exactly is a green roof? 

A green roof is an extension of your existing roof that involves the installation of an interconnected system of waterways and drainage pathways that allow plants to flourish while also protecting the building below. These systems include:

  • Water-proofing 
  • Root repellents 
  • Drainage
  • Filtering cloths
  • Lightweight soils or mixes
  • Plants 

The entire concept of a green roof is to emulate the natural plant systems that provide a positive impact on the environment, giving urban communities the ability to fight the effects of pollution.

Can anyone install a green roof? 

Yes and no. While it is possible to install green roofs on most structures, some are not designed to safely hold the added weight. Filtration and drainage systems, plus the water weight can add 30 pounds per square foot, so it’s important to check with an engineer or specialist before attempting to install a green roof on your own. If you’re hiring a team, they will be able to analyze if your roof is able to sustain the addition of a green roofing system. 

How is a green roof installed? 

Installation is dependent on the type of roof you have. Pitched or slanted roofs are designed for water run off, decreasing the likelihood of eventual water deterioration, which means you don’t need as many protective layers installed. An engineer will assess and determine what your home or business needs for effective installation. 

Once you have a plan of how your green roof will be added, professionals will place a waterproofing membrane over your roof followed by a predetermined layer of pitch. This resin material is commonly used for planting and will help prevent moisture build up by diverting rain water into drainage systems. 

After this is completed, trays made of soil will be shipped to be placed on your roof. These trays are grown specifically for green roofs, so they will be able to hold and grow plants with these specific systems. Before installing these trays, protective edges will be placed around the perimeter of your roof to keep all trays in secure. The trays are then placed in rows along the roof. Most come with feet attached so they aren’t sitting directly on the roof, which can help prevent structural damage. 

Trays will likely have to be cut and trimmed to accurately and snugly fit on your roof. This allows the trays to snap securely into each other, creating a seamless space that can still be easily moved. Once this is done, you can add your plants into the trays and begin the growing of your green roof. 

Different types of green roofs 

There are a few different types of green roofs to consider, and most depend on the types of plants being used, the amount of maintenance you’re willing to do, and the cost. 

An extensive green roof is the most common for residential buildings and the most affordable. It involves a thin layer of growing mix, lightweight plants, no irrigation system, and is predominantly moss and sedum based. These self-sustaining plants allow for minimum maintenance. 

A semi-extensive green roof has a thicker layer of pitch to allow for a larger variety of plants and shrubs. It weighs much more than an extensive roof, involves a higher level of maintenance to keep plants healthy, and costs much more due to the need for irrigation systems. 

An intensive green roof is the most intricate you can get, often involving trees, lawns, and an array of plants. This option is incredibly expensive due to the weight of the pitch, plants, irrigation and maintenance. Intensive roofs are accessible and can often be found on apartments and businesses. 

Benefits of a green roof 

There is an abundance of environmental and cost benefits to having a green roof for both you and the community in which you live, including

  • Distribution of smog, dust, and pollutants 
  • Reduction of heat conducted by buildings 
  • Reduction of noise pollution 
  • Reduction of energy needed to heat homes
  • Reduction of waste generated by your home
  • Improved air quality 
  • Increase of local jobs 

Considerations before installation 

Green roofs are immensely good for many reasons, but they also carry a significant financial burden in some instances. Insurance for them can be pricey, the added weight can cause sagging and damage to your home, and if installed improperly—or just if you’re unlucky—plants can grow roots through the shingles of your roof, resulting in expensive repairs. 
Before you decide to transform your roof, make sure it’s the best decision for your home. If you’d like to learn more about green roofs, their benefits, and environmental factors, visit greenroofs.org. Or, if you’re ready to get to work, give us a call.

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