A green roof, or living roof, is the roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.
General Questions About Green Roofs
How do green roofs work?
A regular roof sends stormwater right to storm drains and streams. Meanwhile, plants on a green roof slow down rain when it reaches t
he roof. When this happens the water absorbs into the soil or evaporates into the air.
The roots of the plants also keep the soil in place as it removes pollution from the water. Together, plants and soil reduce how much stormwater runoff reaches the ground, storm drains, and creeks.
The best locations for a green roof are sunny, horizontal spaces with a small slope. It’s also important that a building can support the weight of a green roof.
What are the benefits of a living roof?
- Save you money on energy bills.
- Extra insulation for your property
- Help you retain and redirect rainfall
- Prevent flooding
- Extend the life of your roof by as much as 10 years
- Increase usable green space
What type of plants can I grow on my living (green) roof?
Intensive commercial grade green roofs can support a wide variety of shrubs, and even some small trees. A less intensive project may include wildflowers and drought-tolerant herbaceous perennials. The most common sort of plants that can be observed in a green roof is all varieties of sedum, perennial plants with thick, succulent leaves, fleshy stems, and clusters of star-shaped flowers. There are over 600 varieties of sedum, so it’s always a good idea to speak to a local specialist about which type are best for your geographic area. Your local rain planner can help you get connected, so just reach out if you’re seriously considering a green roof project and we can help.
How do I know if I can use my existing roof?
We have an allowance available to complete a structural assessment. The assessment is performed to ensure the roof can sustain the weight of the Green Roof. In addition, if you desire, we can give you a price to replace the roof but most people place the Green Roof onto their existing roof. A Green Roof also extends the life of the home’s roof.
What elements are necessary for a successful green roof project?
There are a few key factors that go into executing your project on a new or existing roof. The most important considerations are:
- The Integrity of the Waterproofing Membrane: The roof’s membrane needs to be in good condition to make sure the roof will remain waterproof.
- Structure Load Constraints: The roof needs to be able to hold the added weight of the Green Roof. Before a green roof project starts, a structural assessment needs to be conducted to ensure the roof’s ability to hold that weight. In some cases, additional reinforcements need to be installed to support the added weight.
- The Slope of the Roof: The EcoCline green roof (just one of many brands) can be installed normally on a roof that has less than 3/12 pitch. Any steeper than that some structural components need to be introduced. Due to the implications of a mismatch of this particular criteria, if it’s not crystal clear, we highly recommend consulting with a licensed installer to double-check the specifications. Let us know, and we’ll be happy to match you with a green roof specialist.
- Logistics and Access to the Roof: Finally, our installers need to know what kind of roof access is present at the property to make sure they have the right equipment to get on the roof. Before starting the installation process we will have a structural engineer examine your property to ascertain whether or not any structural supports are needed.
How long does a Green Roof last?
Two things degrade the roof – expansion due to weather and exposure to the UV rays. A green roof dramatically extends the life of the roof by protecting it from those elements. The lifespan of a green roof is over 50 years.
How many days does it take to complete a green roof project?
Once the structural assessment is made and if the roof is fit for a green roof the actual installation can be done in a day or two. Our installers put the roof components in the facility prior to the job and only have to put the pieces together on site. Which reduces the time it takes to finish the project significantly.
Does the owner have to leave the property while the Green Roof is being installed?
If it’s just the Green Roof, which is an overlay of the existing roof, there’s no penetration in the roof, so therefore there’s no requirement for anyone to leave the home. These types of green roof installations typically take about 1 to 3 days.
How much does a green roof typically cost?
Green Roofs typically cost between $20 and $30 dollars per square foot if no roof replacements or structural reinforcements are needed. Structural reinforcements typically cost $3-4 per square foot and roof replacements (with PTO) typically cost $6-7 per square foot.
Can I put chairs on my Green Roof to be able to use it as a hangout area?
A Green Roof is like a lawn in that if you walk the same path every day and sit in the same chair you’ll wear a path in the lawn just like the green roof.
Do Green Roofs help with Heat Island Effect?
Cities are significantly hotter than surrounding areas. This is called the Urban Heat Island Effect. Buildings absorb and re-emit the sun’s heat increasing temperatures in urban areas. Plants absorb heat and provide shade. Green roof temperatures can be 30–40°F lower than those of conventional roofs and can reduce city-wide ambient temperatures by up to 5°F. Green roofs can also help reduce the distribution of dust and pollutants throughout the air which reduces air pollution and smog.
Are green roofs effective in retaining stormwater?
A study done by a University of Toronto civil engineer and co-researchers at the school’s Green Roof Innovation Testing Lab showed that green roofs have the capacity to capture an average of 70% of rainfall over a given time. For an average 1500 roof in DC that equates to saving 26,000 gallons a year from going into the sewer system.
Are green roofs fire retardant?
Living roofs have much lower burning heat load (the heat generated when a substance burns) than conventional roofs do which reduces fire risk to the building.
Are Green Roofs compatible with Solar?
Green roofs can be integrated with solar panels and actually increases their efficiency. By reducing the temperature of your roof, your living roof actually improves the performance of photovoltaic cells. Additionally, integrating green roofs with solar panels gives you the opportunity to stack available incentives and rebates.
Does having a green roof affect your property value?
Green roofs, like other forms of green infrastructure, are beautiful and increase property value. In New York City for example, apartments with green roofs had about 16% higher rental fees than buildings without living roof space. The same goes for residential property owners, green roofs can boost property value by 15%!
Is it true that green roofs reduce outside noise?
Installing a living roof can reduce sound from outside by up to 50 decibels. Replace annoying honking and construction noise with peace and quiet.
Are there energy savings associated with a Green Roof?
Living roofs provide insulation and help keep buildings cold in the summer and warm in the winter. This leads to significant energy savings. Research published by the National Research Council of Canada found that an extensive green roof reduced the daily energy demand for air conditioning in the summer by over 75%.
What if my green roof gets damaged?
There’s a warranty for the establishment if something that major happens. In most cases, damage will be covered under your homeowner’s insurance as a fixture.
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