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Lancaster School District Green Roof Report Card

Green Team at Green Roof Technology, - Wednesday, November 16, 2011

By Andrew Cole Yanders

 

Photo By ~ Kat Harrold

Last week, Andrew and Kat traveled to Lancaster, Pennsylvania by request of the School District of Lancaster and LIVE Green Lancaster to tour and evaluate three green roofs in the district.  The report card was not good.  Parent-teacher conference bad.  We have made available a detailed school-by-school evaluation of each roof, containing a diagnosis and recommended treatments. 

To find out more about the diagnosis and recommended treatments visit our Resources page.

Extensive Green Roof Maintenance

Green Team at Green Roof Technology, - Tuesday, September 13, 2011

 

Extensive green roof being planted - Kat Harrold 

 

By Kat Harrold GRP

A common misconception with green roofs, especially extensive ones, is that they require no maintenance.  While some green roofs may be fairly self-sustaining and require little maintenance there is still some regular maintenance required to keep the green roof as a system working to it’s fullest. The three main things to consider are the plants, media, and timing.

Plant selection is very important in determining when you need to fertilize and weed.  Also deciding what is a weed is very important.  A weed very often is as subjective as beauty; often it is simply within the eye of the beholder.  Newly planted green roofs will need more weeding than established roofs to cut down on competition of resources while they try to get a foot-hold.  

Green roof media blended properly should have very little organic matter.  While extensive green roofs generally don’t require much additional nutrients they do need a balanced low-level fertilizer with micro-nutrients applied twice a year.  Do NOT use an organic fertilizer such as manor or compost.  The organic material can break up into very fine particles, which over time could clog the filter fabric and cause drainage problems.  Specifics on fertilizer content for green roofs can be found in the translated German green roof guide the FLL.

Timing is very important in terms of preserving both plants and your sanity.  On an establishing extensive green roof be sure to weed once every 2 months for the first year.  You can cut back your weeding to 3-4 times a year once the plants have established.  Taking extra care in the springtime and after a heavy rain can save a lot of time weeding seedlings instead of full grown weeds.  Grasses should be cut back in late winter to early spring.  FLL specified fertilizer should be applied once in the spring and once in the fall for the first year.  Have a professional check your roof after that to advise how much is needed there after.  

The Sky is Falling: A Critique of Failed Sloped Extensive Green Roofs

Green Team at Green Roof Technology, - Tuesday, September 06, 2011

By Jorg Breuning


As of late we have been receiving more and more calls from building owners in distress about their green roofs.  The most serious of these complaints being erosion problems on their sloped roofs.  Sloped green roofs are a bit more complicated to design, install, and maintain than flat roofs and as a result people who disregard or don't know of the established FLL guidelines for sloped roofs, have created dangerous and costly situations ranging from mudslides to roof collapse.

One of the most infamous of these rooftop blunders was last winter in St. Charles, Illinois.  The project was designed to be the largest sloped roof in the US and during a heavy snow storm the roof collapsed.  Fortunately no one was hurt however the damage was devastating.  

Why did the roof collapse?  The problem lies in the drainage.  Snow is frozen water and where you have more water accumulating on a roof you will also have greater amounts of snow accumulate.  This insufficient or clogged drainage system and poor growing media is the most likely culprit in areas that held water or snow.  All this added weight during an extreme winter put the roof way beyond its capacity.

Sadly, this situation and others like it could have been avoid simply by hiring a true expert and checking their performance history for similar projects.  To read more about the dangers of improperly design sloped extensive green roofs and how to avoid them click here.

Below the renovated roof after it collapsed. Suddenly the green portion shrinked by at least 1/4.

Leaky Roof Insurance

Green Team at Green Roof Technology, - Monday, May 23, 2011

Testing a roof for leaks using an Electric Field Vector Mapping system 

It's been a tough week in terms of trying to get working conditions dry enough to do anything let alone put up a roof.  If your are planning on putting up a new roof and or green roof, be sure to consider getting a waterproofing membrane that is compatible with an electric field vector mapping system (EFVM).  This beauty can be installed before or after a new waterproofing is assembled and can find leaks that wont show up in a traditional flood test.  A leak may be in one section of the house however, the water may travel several feet before coming through the ceiling and playing a nice tune in your pets water bowl.  Having one of these systems prevents you from turning your roof into swiss cheese or a patchwork quilt trying to find and fix that illusive leak.  This also saves your green roof from total annihilation by knowing exactly what area to dig up.  In the long run this saves time and money and is cheaper than most waterproofing membrane insurance.  

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