Bayside Park Farm living roof: Difference between revisions

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Abstract

Humboldt State University Engineering 305 class volunteered to construct a living roof for Bayside Park Farm a community farm in Arcata, California. The project would be the roof of an animal hutch that would simultaneously be built as this roof was being constructed. The type of living roof attempted to be created would be an extensive living roof because it would allow for the ability to be low maintenance and easiest to construct. Thus far the roof seems to be serving its purpose as a roof for a housing unit.

Background

Bayside Park Farm located in Arcata California in the United States and also goes by the name Arcata Educational Farm. It is a Community Supported Agriculture (CSA) facility that also acts as an educational farm. Our (Caroline, Mayara, and Amber’s) Engineering 305 class during the North American Spring 2015 semester will be constructing a functioning living roof. This living roof must attend to the owner's specifications regarding its dimensions and purpose, which are that the living roof be made on a small animal hutch that is currently being made. The construction and development of the living roof will span from January 2015 until May 2015.

Problem statement

The objective of this project is to create a functional, sustainable and sufficient living roof at Bayside Park Farm. A living roof also known as garden roof or green roof, is a roof that provides protection to the roof base and helps reduce water runoff and allows for some temperature regulation inside the housing unit. Furthermore it can be used for improving air and water quality, promoting energy conservation, providing food, and creating an ecosystem within an urban area. If possible we plan on using affordable or recycled materials that may be donated for the roofs construction and by doing so we will cut costs down for the construction of the roof. By doing this we aim to create a feeling of community involvement and create another area of the farm that may teach the community about an alternative to roofing.

Criteria

The criteria was defined according to the farms purposes and preferences, which were very loose and only asked that the roof serve as an educational tool that could be used over time. This criteria was used as a guide for the construction of the roof. Where values were higher is where the most effort was placed in providing those demands in the construction of the project. The scale (1-10) represents the importance level of the constraint of each listed criteria.

Literature Review

Living roof basics

The basic components of green roof systems are waterproofing, soil and plants. It really is that simple. The combination of these material is easy and the success of all living roofs depends on the types of plants used and an understanding of how these combined materials will work.^[1] An understanding of the type of environment the roof will be located in is also important for the success of any living roof. For example here in Humboldt County earthquakes pose a risk as well as a high precipitation level in the fall and winter months, however in the spring and summer months there is little to no rain fall. Design should account for earthquakes and the forces it will create on the building as well as any irrigation or drainage components that will function during both during the wet season and dry season. These however are design features that should be asked when building the structural support and housing unit the living roof will be placed on top of before and during construction of both the roof and the house or structures for the roof. For the purpose of our project we were only asked to concern ourselves with the construction of the roof itself because the farm would be responsible for the hutch or housing unit and the structural support. This means we focused on the weather aspect of design for the roof. Living roofs are that simple especially for small designs. Living roofs are becoming increasingly popular in North America and are starting to show themselves in large scale industrial buildings. The design and construction of those types of roofs are a little more complex and a lot more labor intensive, but the end result is worth the effort

Living roof concerns

A main concern regarding living roofs revolves around the types of vegetation that is being used because the performance of the living roof is the plant communities. Concerns regarding the plant communities on living roofs deal with weather factors such as wind stress and over exposure to the sun, however in the literature the main focus has been on wind stress because plants are not generally accustomed to the heights that roofs generally are. There has been some practice of using native plant species because they are generally most accustomed to the region the roof is. However, in some of the literature discusses native plants not working on extensive living roofs because of the shallow soil depth generally found on extensive living roofs.This then means that not only is wind stress the main factor in determining the types of flora being used but that the rooftop itself is challenging for the survival of plants.^[2]

Another more recent concern that has appeared during the increased popularity of living roofs is water-quality of the storm water runoff from living roofs. The literature suggestes that living roofs may act as another source surface-water pollution primarily because of the nutrient content found in the growing medium and soil used. ^[2] To combat this we tried to use soil and growing mediums that not only would maintain the health of the plants but that were already found on the farm. We went with a perlite and coco peat combination.

Types of Living Roofs

In the world that is living roofs there are generally two types of designs. They are intensive and extensive. More recently there has been the inclusion of a hybrid living roof that is a combination of these two types called semi-extensive.

Intensive

Intensive living roofs are found on industrial building such as parking garages or other public buildings usually heavily trafficked by humans. Intensive living roofs have a very high plant diversity because these roofs have the ability to provide very deep soil potential for these various plant communities. Intensive living roofs may be viewed as actual gardens on roof structures not just because of the plant diversity but because those plants are maintained on an individual basis similar to what is found on ground level. This also means that intensive living roofs have irrigation systems built into the living roof system. The combination of these two things makes intensive living roofs very high maintenance physically and monetarily. ^[3][4][5][6]

Here is a useful advantages and disadvantages look at intensive living roofs that may express the concept a little easier. ^[5]

Extensive

Extensive living roofs are low maintenance roofs because this design type is used most often used with lightweight and low height buildings. The soils in extensive living roofs are generally shallow. Especially much shallower than intensive living roofs because the plant communities in extensive living roofs tend to be self-generative plants or types of plants that can survive in some sort of “desert” like environment. Some types of plants may include shrubs, grasses, mosses, and indigenous plant species. ^{[4][3] [6][5]}

Here is a useful advantages and disadvantages look at extensive living roofs that may express the concept a little easier.^[5]

Semi-Extensive

There is more information on semi-extensive living roofs out there, but the main idea behind the design is that it is low maintenance like an extensive roof, but has deeper layers for growing medium like an intensive roof has. Meaning high diversity of plants with low-input.^[3]

Living roof design

The design of a living roof depends on the wants and needs of those requesting one for their home or industrial units. A living roof should be viewed as another artistic expression of self because they can be built, placed, and designed in a manner that expresses either the designer or the one inhabiting the structure. However, the one aspect of living roofs that generally has laid out plans or rules that should be followed are the different layering components of living roofs.^[1]

Below is a pictorial and table example of the different types of layers that may be found generally on intensive roof systems, but may still be applicable to extensive or semi-extensive designs.^[7]

Construction

The construction of the roof took a combined total of four days with the effort of two people at a time.

Design

The living roof was designed based off the information given by the farm that the hutch being built would be a 4.5ft by 4.5ft structure. We were not told anything else about the hutch being built other than its proposed size. Because of the size of the roof it seemed practical to give the roof no more than a two degree slope to prevent soil erosion and allow water to drain naturally. Because we knew nothing of what the structure would look like we assumed an overhang of about three inches. The roof was asked to be built as low maintenance as possible therefore a simple one inch open was allotted for the back of the roof to allow water to flow backward naturally.INSERT EQUATION.

Here are the layers of our roof design.

How to Build

Proposed timeline

Costs

This is the budget for the roof. Almost all of the items were donated.

Operation

Maintenance

The roof was designed specifically for low maintenance therefore the farm will have to do some weeding and if required some watering.

Schedule

For the functional longevity of the roof the farm should do minor maintenance as suggested.

Daily

• A soil finger test maybe done to make sure the soil is not too dry.

Weekly

• A soil finger test.
• Check on the health of the plants. Curb any growth that may hinder/puncture the membrane.
• Check for any leakage.
• Check for any membrane/pond liner tears or punctures.

Monthly

• A soil finger test.
• Water.
• Any weeding. Making sure to stop the growth of anything with tap-roots that may compromise the membrane.

Yearly

• Harvest succulents if desired.
• A soil finger test.
• Check the life of the membrane.
• Check on any touch ups if they were done.

Conclusion

Testing results

Testing involved checking on the roof once a week to make sure the structure was still standing and that the plants were still alive.

Discussion

SO far everything seems fine.

Lessons learned

A lesson learned was making sure the appropriate tools were on hand at all times.

Next steps

And the next step will be to make yearly visits to check on the longevity of the roof.

Troubleshooting

This is only how to troubleshoot basic operation. For complex issues, the solution might just say contact ________. It should be a table in this format:

Team

Introduce team and semester in the following format:

• Caroline
• Mayara
• Amber

References