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Green roofs (FLASH)


What is a Green Roof

Green roofs are one thing that can decrease global warming from all angles. Lancaster County is installing some green roofs of its own in an attempt to preserve its own environment. A green roof is a roof that is covered in soil and plants. Green roofs are usually made of grass, moss and other types of plants that can withstand a wide range of weather conditions.

What is Lancaster County doing with green roofs?

The difference between Extensive and Intensive green roofs.

The make up of a green roofs.

What are the benefits of green roofs?

How can you get a green roof of your own?

You still want to build a green roof?

Topel Residence Case Study.

The future of green roofs.

What is Lancaster County doing with green roofs?

There are currently a few green roofs in the area. One of them is located at a household and the other is found on a city building.

In Wrightsville the Kin residence has a green roof on their house.

The other building is located in Allentown. The building has two winter gardens on its second floor, and a vegetated roof.

Earlier this year Pennsylvania gave Lancaster County a $500,000 grant to build some green roofs of its own. There were initially 6 buildings proposed, but over the last couple months of planning only 5 will receive them now.

The first building that will receive one will be the National Novelty Brush Building on 505 E. Fulton Street. The construction on this build will start in late April or early May.

The beginning of construction on the remaining buildings will follow sometime after this building is complete. The rest of the buildings that will receive a green roof are.

  • The Bare Building at 202 N. Duke Street

  • Penn Stone, 190 W. Ross Street

  • Two Dudes Painting, 744 Poplar Street

  • Box Company Flats, 225 E. Grant Street

Green roofs absorb pollutants and CO2 gases. These pollutants and gases are the factors that created global warming. Green roofs can also prevent storm water run off, and that reduces flooding in city areas. Green roofs also add to the longevity of your roof. The effects of harsh weather on your roof are absorbed by green roofs, which can lead to the doubling of your roofs’ life.

Lancaster County received a $500,000 grant this past November. Six buildings were selected to receive green roofs paid for by this grant. Project Green Lancaster will take a look at these buildings and the benefits that theses roofs have on Lancaster and the buildings that house them.

The difference between Extensive and Intensive green roofs.

There are two types of green roofs. An extensive green roof is a lighter and cheaper roof than an intensive green roof. Extensive green roofs are typically on roofs that slope. They can be used on roofs that have up to a 33% of a slope. The types of plants that are typically found on extensive green roofs are

  • moss,

  • grass

  • flowers

These types of roof usually don’t need much interaction after then are planted. They also aren’t usually designed for the weight of a human. These roofs are what you would typically find on someone’s house or garages.

Intensive roofs are made for roofs that can handle a much larger amount of weight. They are designed specifically for human interaction, and are far more involved than an extensive green roof. Intensive roofs can have a wide range of things planted on them such as large bushes, and trees.

The only real limit to what can go on an intensive green roof is the amount of money that can be spent on one, because they are much more expensive. Intensive roofs are also typically more pleasing to the eye as well.

Intensive roofs are typically flat and are found on the buildings that can handle a large weight such as warehouses, office buildings and parking garage roofs. The green roofs that will inhabit Lancaster will be intensive green roofs.

The make up of a green roof.

A green roof is made up of more than just dirt and plants. Each component is just as important as the last and equally are all important to the construction of the green roof.

  • The first component of a green roof other than the roof itself is the waterproofing membrane. The waterproofing can be either organic or synthetic. The fear of using an organic waterproofing is that roots can penetrate this membrane causing leakage. Due to this fear most green roofs contain a protective root barrier to prevent roots from breaking through this extremely important layer. Usually a concrete layer used as the barrier to prevent the possible damage of roots.

  • The next layer is an optional layer but can be beneficial. A layer of insulation can help prevent roofs from releasing hot air in the winter and cold air in the summer. Also the strength of most types of insulators means that the weight of the remaining layers of the roof will not damage it.

  • Typically the next layer is the drainage layer. The purpose of the drainage layer is to eliminate excess rainwater. Draining the excess rainwater helps assure that the plants will be able to grow properly, because they will be storing the right amount of water. The excess water that is captured by the drainage layer normally run to a roofs normal gutters or storm drains.

  • The next layer is a filtering membrane that is used to allow things such as air and water to pass through. The filter membrane also keeps the soil in place and prevents things such as plant debris, and soil particles from clogging the drainage layer.

  • The next layer is extremely important. In order to properly maintain a green roof the soil or growth media must be mixed properly and carefully. The best way to go about this is to have a soil expert take care of mixing the soil. The soil should be partially made of a soil that is common to the surrounding area and partially be made of organic materials. Typically the soil will be a quarter organic and the rest will be made up of inorganic materials in order get proper drainage, and still give the plants natural nutrients for the plants. This layer must also be thick enough that the plants will not be damaged by extreme heat or extreme cold.

  • The final layer of the roof is of course the plants. The plants on a green roof differ with climates. Plants that might be able to withstand high temperatures but not very cold temperatures might not be ideal for certain areas. Lancaster is a perfect example of this. Although the summers can get very hot sometimes, the winters can get just as cold. The types of plants also differ from roof to roof. Depending on the importance of appearance of the roof the look of the plants can differ too.

  • Grass

  • Moss

  • Flowers

  • Vegetables

  • Bushes

  • Trees

These are all possibilities of things that can be grown on green roofs. The plants also can change depending on the way someone might want their roof to physically look.

The types of plants also differ on the type of green roof. Extensive green roofs can not handle the weight of a tree, where an intensive green roof cause hold the weight of trees and many other things.

What are the benefits of green roofs?

Green roofs have many advantages but it has a much larger impact on city environments. Since cities don’t have as many plants and trees in them as other areas, a green roof can have a big impact on the building it inhabits and its surroundings.

One of the most significant advantages of a green roof is its ability to manage storm water. Green roofs absorb storm water which keeps the in the soil and reduces strains on sewer systems, rivers and streams. The rain water is absorbed by the soil and plants, and then released back into the atmosphere as any other area with plants and vegetation.

  • Not only do green roofs absorb rain water but they also absorb the pollutants that are found in rain water. The soil and plants act as a kind of filter for pollutants. This is also a form of water purification.

  • Cities suffer from a problem called the urban heat island effect. The urban heat island effect is caused by the concrete and asphalt that make up most cities absorb heat and then reflect it back out at a higher temperature.

  • A city like Lancaster although not as big as most cities, is still very susceptible to this problem. In nature areas, plants and vegetation absorb this heat actually keeps the area cooler. Green roofs do the very same thing. Place a green roof on the top of city buildings would keep cities cooler and eliminate the possibility of urban beat island effect. 

  • Green roofs absorb CO2 gases that are emitted into the air along with other air pollutants. According to the American Lung Association, Lancaster has the 24th most polluted air by long-term particle pollution. Green roofs over time could bump Lancaster off this list and improve the air quality of the whole county.

  • Insects and birds also benefit from green roofs. A green roof gives them another place for them to inhabit. Green roofs also are less likely to have people invade them which makes it that much more appealing to birds and insects.

  • Green roofs along with all of its environmental benefits offer economic benefits as well. The first benefit is that it will help extend the life of your roof. Green roofs absorb a lot of the damage that a regular roof can take over the course of the years. Over the years the money that save on roof repairs will help pay off the green roof.

  • Green roofs also help reduce energy cost as well. Green roofs keep buildings warmer in the winter and cooler in the summer. This cuts back on the use of heating and air conditioners over the course of a year.

  • A green roof can also have a positive effect on a business too. Going green is something that is seen in a very positive light, and the addition of green roof can give a business a very positive image. A company like Two Dudes painting who already use environmentally friendly products will only increase its positive image when it receives a green roof.

How can you get a green roof of your own?

  • When researching getting a green roof of your own, there are a few things you need to consider before making any decisions. The first would be what kind of green roof do you want to build?

  • If this green roof is going to be located on your house you might want to consider an intensive green roof due to the amount of weight your roof can take.

  • If this green roof is for an office building or a building that has the capability to hold more weight, than you might want to think about building an extensive green roof because it’s has more benefits to it due to the different types of plants you can grow on it.

  • The next step you’re going to want to take is contacting a contractor that works on green roofs. There is a contractor in Philadelphia by the name of Roofscapes Inc. that installs green roofs, and is working on the construction of the National Novelty Brush Building. A contractor will let you know what kinds of precautions need to be taken when building on the roof if any.

  • From there you might want to consider someone handling the building because green roofs are a rather new thing to America so the normal person’s knowledge on construction on one of these roofs is limited.

You still want to build your own green roof?

  • If you really want to build your own green roof and do without all of the extra construction cost that you would have to pay, then my recommendation would be to start small.

  • A shed in your backyard would be a perfect place to start. It is small, easy to get on top of, and if there is any damage done to it, it is less expensive to fix then say your house.

  • The first thing your going to need to do is make sure that the roof is going to be able to withstand some extra weight on it. An old rusted metal shed may not be the best candidate, but a shed that is sturdy will do just fine.

  • Next, you’re going to want to get the measurements of the roof. This way when your building frames for the plants and soil the will be able to cover the whole roof.

  • Then, you’re going to need some plywood, regular wood that will be able to outline the roof of the shed. You’re also going to want some screws and a screw driver.

  • The next thing you’re going to want is some type of waterproofing membrane. When doing the job yourself, the easiest type of membrane to use will be butyl lining. It comes in sheets and is easier to use then something you would have to paint on.

  • Finally you’re going to want to have some plants and soil. Since the scale of this green roof is not a large as a regular green roof, the importance of the soil and plants is somewhat less.

  • Now comes the actual construction of the roof. The first thing you’ll do is create wooden frames to hold the plants and soil. You will do this by building a box that outlines the roof. Then you will divide the insides of that into equal parts to hold plants and soil in sections.

  • Next, you’ll wrap the butyl lining around the pieces of plywood. The plywood is then placed on the roof and screwed down.

  • The wooden box that you made is now placed on top of the plywood and screwed down.

  • Then you want to fill the roof with soil and plants. You can choose a wide range of plants but you might want to choose plants that don’t grow as height because they might suffer some wind damage.

  • Finally, and probably the best step is to sit back and admire your roof. Over the years till provide you with not only something beautiful to look at, but it will also give you positive feeling that you’re doing something positive for the environment.

  • green roof on top of a garden shed

  • Topel Residence Case Study

  • The Topel family residence is located in Kennet Pennsylvania, and it will have a green roof on one of its roofs. The house was just recently LEEDS certified, and is now the 401st LEEDS certified building in the nation. 

  • The LEEDS program is a program that certifies a high standard of green building. LEEDS concentrates its measurements on localizing the materials, energy efficiency, water efficiency, and other areas.

  • The house is still under a few minor constructions but it is pretty much ready to move into.

  • The house is made of localized products. There are wooden shutters that slide to close off the windows that are made from wood that came from old torn down bars. That is just one example of something that this house uses that is recycled and local.

  • One of the three roofs is receiving a green roof. The waterproofing of the roof is done, and they are now waiting on the Weston Green Grid system to be able to lay soil and plant its vegetation. At the moment the plans are to just plant sedum on the roof.

  • Along with the building of the house, Mr. Topel is currently writing a book about the building process. The book will cover the process of applying for LEEDS certification, the materials that were used in make the house, the different types of systems used to heat the house, light the house, and all of the other things that make a regular house.

  • The difference between a regular house and this one is how it works with the environment instead of against it.

  • The future of green roofs.

  • Although green roofs are a new type of initiative to America, they are something that have been nearly perfected and used widely in Europe. Germany is the leader in green roofs, and the new technology that is making them more and more available around the world.

  • With a county and government that are looking for answers to help our planet, green roofs could become a big piece of the puzzle that could help restore earth to a better form.

  • Since it doesn’t look like we will be getting rid of buildings to grow gardens anytime soon, we can place them on top of buildings to replace some of the nature we have lost.

  • In the not so distant future green roof technology can improve and a green roof will be something that everyone could have. Can’t you just imagine how beautiful it would be if the next time your on a plane going across the country and all you can see for miles is green?

This site was created by Dennis Keenan(email) who is a student at Millersville University of Pennsylvania

Last updated on February 10, 2008

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