Abstract
The purpose of the project was to educate Nature Center visitors on the benefits of living green roofs, to enhance the aesthetics of the Nature Center, and to inspire others to build their own green roofs. The Dune-Gineers Green Roof was built at the Friends of the Dunes Nature Center by students at Humboldt State University Engineering 215 class.
Background
The Friends of the Dunes is a non-profit organization, and their Coastal Nature Center is a place where they promote green solutions by educating visitors. They work to protect and preserve the natural habitats of the dunes. The Friends of the Dunes originally planned to have a living green roof put on their back terrace, so the terrace was built to be able to hold a heavy garden. They tried to get a living green roof built, but the quote given to them by the hired company was too expensive. When they were later presented with the opportunity for student engineers to build a green roof for much cheaper, they decided to give us the job.
Problem statement
The FotD wanted a green roof to be installed. They wanted it to have native Californian dune plants to live on it.
Problem Analysis and Criteria
| Criteria | Weight | Description |
|---|---|---|
| Aesthetics | 10 | Description |
| Support Local Plants | 9 | Description |
| Cost | 3 | Entire design must cost less than $400. |
| Weight | 5 | Constraint description |
| Safety | 5 | Don't collapse description |
The Solution
The design solution that best met the criteria for the project required the modification of two seperate components within the CCAT gray water system. The Switch and Swap is the grease removal unit. The Surge tank has been modified to reduce problems during operation.
How to Build
The green roof is installed on the smaller awning in the back of the Nature Center. An additional layer of waterproofing paint is added to make sure no leaks occur. Concrete blocks are carried up on a twelve-foot or higher ladder, and stacked two high around the edge of the roof, four inches from the gutter. Gravel is then brought up in buckets and spread to a height of one inch. The separation fabric is placed on top, leaving 4 inches of extra cloth along the edges. The cloth is not wide enough to completely cover the bottom of the roof, and needs to overlap by one inch at any seams. Four inches of sand is then added on top of the separation fabric, excluding the sides. Along the insides of the blocks and against the wall, extra gravel is added to a thickness of one inch and a height of four inches. The extra four inches of separation fabric is then used to separate this column of gravel from the four inches of sand. Extra sand is added to the roof to fill in any low points on the roof. Once the layers are in place, a micro sprinkler system is installed. The erosion control blanket is then placed on top of the sand. On the edges of the roof it is pushed down into the sand to hold it in. Stakes are taken from the surrounding green roof where the erosion control blanket has decomposed and are used to hold down the new blanket.
Costs
| Material | Amount | Price | Supplier |
|---|---|---|---|
| Hydrostop Protection Layer | 1 bucket | $0.00 | FOTD |
| Protection Fabric | 500 sq/ft | $60.00 | Miller Farms |
| Gravel | 1.4 cb yards | $70.00 | Miller Farms |
| Separation Layer | 500 sq/ft | $60.00 | Miller Farms |
| Edge Concrete Blocks | 42 | $0.00 | FOTD |
| Erosion Control Blanket(CS3) | 500 sq/ft | $170.00 | Western Excelsior |
| Sprinkler System | 1 | $113.00 | Home Depot |
| Tax | $34.92 | ||
| Total | $517.92 |
Discussion
Instructions for Implementation and Use After installation, more plants will need to be added to the roof. These can be added by carefully planting on the roof, or by spreading seeds under the erosion control blanket. Extra heavy watering will be needed initially to get the plants established.
Periodic Watering When the plants on the roof look wilted or there has not been any substantial rainfall, the roof will need to be watered. This can be done by turning on the spigot on the north side of the building, two feet of the ground. Water should occur no more than twice a week, and for only twenty minutes.
Yearly Cleaning The maintenance of the green roof will require occasional pulling of weeds, cleaning of drain gutter, and inspecting of the sprinkler heads. Quarterly flushing will require approximately one to two hours.
Safety Precautions As the blocks on the side of the roof are not attached to anything, great care should be taken when accessing the roof. A 12 foot or higher ladder is recommended.
next steps
We are looking forward to building the roof!