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Difference between revisions of "Bayside Park Farm living roof"

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=== Maintenance ===
 
=== Maintenance ===
The roof was designed specifically for low maintenance therefore the farm will have to do some weeding and if required some watering.
+
The roof was designed specifically for low maintenance therefore the farm will have to do some weeding and if required some watering. However, side paneling was placed on the structure and that was not accounted for in the roof over hang calculations. This means that when the roof drains water the back paneling is getting wet because the structure is now extended out an extra three inches. Making sure that back paneling wood does not rot or mold is pertinent to the health of the system.   
  
 
=== Schedule ===
 
=== Schedule ===
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*Check on the health of the plants. Curb any growth that may hinder/puncture the membrane.
 
*Check on the health of the plants. Curb any growth that may hinder/puncture the membrane.
 
*Check for any leakage.
 
*Check for any leakage.
*Check for any membrane/pond liner tears or punctures.
+
*Check for any membrane/pond liner tears or punctures.
 +
*Check back paneling if rain has fallen because it is possible the wood may rot or mold.
 +
*Weed if necessary. making sure to pull anything that may have a long tap root. 
  
 
;Monthly
 
;Monthly
 
*A soil finger test.  
 
*A soil finger test.  
 
*Water.
 
*Water.
*Any weeding. Making sure to stop the growth of anything with tap-roots that may compromise the membrane.  
+
*Any weeding. Making sure to stop the growth of anything with tap-roots that may compromise the membrane.
 +
*Check back paneling if rain has fallen because it is possible the wood may rot or mold. 
  
 
;Yearly
 
;Yearly
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*Check the life of the membrane.
 
*Check the life of the membrane.
 
*Check on any touch ups if they were done.
 
*Check on any touch ups if they were done.
 +
*Check back paneling if rain has fallen because it is possible the wood may rot or mold.
  
 
==Conclusion==
 
==Conclusion==

Revision as of 16:08, 8 May 2015

Engr305 Appropriate Technology page in progress
This page is a project in progress by students in Engr305 Appropriate Technology. Please do not make edits unless you are a member of the team working on this page, but feel free to make comments on the discussion page. Check back for the finished version on May 15, 2015.



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 Northern 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. The 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.

The original suggested project was to build a living roof over a cob oven that would be rebuilt. However, at the request of the farm our project was changed to building a roof for a future animal hutch that the farm was wanting to build.

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.

Criteria Constraints Weight
(1-10)
Functionality Must serve recreational and educational purposes.
10
Safety Must be able to hold while put on a structure.
10
Durability/Resistance Must be weather resistant.
9
Maintainability Must be low and easy maintenance.
8
Aesthetics Must be pleasing to the eye.
6
Weight Must be able to hold at least 20lbs per square meter.
4

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]
Advantages Disadvantages
Diversity of plants Greater weight load on roof
Good insulation properties Need irrigation and drainage system
Simulate wildlife garden Greater weight load on roof
Attractive aesthetically Need irrigation and drainage system
Accessable/recreation High maintenance and cost
Longer membrane life High maintenance and cost
Storm water retention capability More complex

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. [3]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.[4] Some types of plants may include shrubs, grasses, mosses, and indigenous plant species.[6]

  • Here is a useful advantages and disadvantages look at extensive living roofs that may express the concept a little easier.[5]
Advantages Disadvantages
Lightweight. Generally no reinforcement Less energy efficient
Suitable for large areas Less storm water retention benefits
Roof slope 0degrees-30degrees Limited choice of plants
Long life and low maintenance Not accessible for recreation or other uses
No need for irrigation or specialized drainage system. Unattractive usually in the winter season
Inexpensive
Vegetation can grow spontaneously

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]

  • Here is an example of generic layering usually found on industrial living roof systems. Some of these layers may be applicable to smaller scale roofs.[7]
Layers Description
Deck Layer Is the foundation of a green roof and may be of concrete, wood, metal, plastic or a composite material
Leak Detection System (optional) Leak detection systems are often installed above the deck layer to identify leaks, minimize leak damage through timely detection, and locate leak locations.
Waterproofing Layer Very important to prevent water damage through the deck layer. This layer must be entirely waterproof and long lasting. Several waterproofing materials can be used, like thermoplastic membranes, elastomeric membranes, modified bitumen polyvinyl chloride (PVC), applied rubberized asphalt, built up bitumen and others. The waterproofing material may be loose laid or bonded, which is more recommended.
Insulation Layer(optional) Usually located above, but sometimes below, the waterproofing layer. Its function is to increase the energy efficiency. Recommended for metal roofs
Root Barrier Used to protect the waterproofing membrane from root penetration
Drainage Layer Placed between the root barrier and the growing media to remove excess water from the vegetation root zone. Must consist of synthetic or inorganic materials. The thickness of the drainage layer type is an important design decision. For extensive green roof systems, the depth of the drainage layer usually varies from 0.25 to 1.5 inches thick and increases for intensive designs.
Filter Sheet Consists in a “semi-permeable needled polypropylene filter fabric placed between the drainage layer and the growing media” in order to prevent the drainage layer to clog by the migration of some particles from the media into it. The filter sheet must allow the water migration into the drainage layer
Growing Media Usually 3 to 6 inches deep and composed of approximately 70 to 80 percent lightweight inorganic materials like clays, pumice, scoria or other similar materials. The remaining media must not exceed 30 percent organic matter because it can transport nutrients into the runoff from the roof and clog the permeable filter sheet.
Plant Cover It is the top layer and consists of plants that are non-native, slow-growing, shallow-rooted and perennial. The selected plants must be able to withstand harsh conditions at the roof surface. For drought periods it is recommended the installation of a watering system.

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.

  • We used this equation to determine the weight of the roof itself so that the structure may be built with the weight in mind.

[math]density = {mass \over volume}[/math]

  • Here are the layers of the roof design being built.
Layers Description
Rubber Membrane This first layer protects the wood from any moisture and prevents any leakage.
Pond Liner This layer protects the rubber membrane from any moisture exposure.
Drainage Rocks These rocks will allow the drained water to run-off slower.
Lava Rocks These were used because they will allow the water to pass through easily. There will be no water build up or blockage which may cause any type of root rot or flooding compromising the layers.
Landscaping Fabric The fabric is a permeable material that will prevent the soil from blocking the drain rocks or lava rocks. Without the landscaping fabric the water would not be able to drain properly which may cause root rot.
Perlite This will add water retention.
Coco Peat This soil has very low nutrients, but is very good at maintaining moisture.
Plants Succulents were the desired plant of the farm.
Lava Rocks These were used again, but this time as a soil protector instead of wood chips because the wood chips have the potential to increase the soil acidity.
  • Here is a crude example of the layers placed on the roof.
Living Roof Design. Image credit: A.R.Shearer



  • Here is the design the roof is based off of.
Living Roof Design. Image credit: A.R.Shearer
Living Roof Design.Image credit: A.R.Shearer


How to Build

How to Build a Living Roof
ImageStep
roof naked. Step 1: The first step, was to construct the roof by placing the side panels on the roof base because the base itself was already laid out for us by the farm. Because the wood was milled and untreated a wood preserve was used once the side panels were placed on the roof base.
rubber membrane Step 2: The rubber membrane had to be cut to size. Because of this it would have been best two have a second membrane on hand because cutting it down to size made it smaller in places it needed to be longer in. If the membrane were not cut to size then bunching around the corners would be too bulky and had the potential to cause leakage. The membrane was then one-way cemented on.
pond liner Step 3: Pond liner was doubled up and blanketed over the rubber membrane. On the free-standing back panel the pond liner was wrapped around the panel that acted as the drainage panel.
lava rocks Step 4: Drainage rocks were placed at the drainage opening.However, river rocks were also used along with the drainage rocks because the river rocks were easier to get a hold of and cheaper. About a quarter of lava rocks was evenly placed across the roof and over the drainage rocks.
landscape fabric Step 5: One layer of landscaping fabric was placed over the lava rocks. We did not double up the landscaping fabric because we felt it would not allow adequate drainage. The landscaping fabric will hold the soil in place and allow only the water to percolate through.
perlite Step 6: Perlite was evenly spread across the landscaping fabric. Perlite because it retains a lot of water.
soil Step 7: Coco peat was placed over the perlite.Coco peat because moisture retention was very important to the functionality of the roof therefore a soil that had a high water retention and a low nutrient content seemed ideal for succulents in our climate.
plants Step 8: The plants were transplanted from pots onto the roof. The farm already had these succulents and wanted to expand their succulent collection.
soil protection Step 9: The left over lava rocks was used to finish the roof. The idea is that the rocks will protect the soil from wind and over exposure.

Timeline

Weeks Tasks Observation
16-Fev Roof sizing design (figure out dimensions and establish the adequate amount of materials).
23-Fev Listed all needed materials and their looked prices.
2-Mar Finalize the budget and start looking for donations.
9-Mar Look for donations (delivering donation letters).
16-Mar Look for donations (delivering donation letters).
23-Mar Look for donations (waiting anwers from potential donators). Got the donations.
30-Mar Transport materials to the farm and start preparing the wood. Wood without treatment, had to treat before constructing.
6-Apr Build the base of the roof. The farm provided the foundation.
13-Apr Put on the first layers (protection/root barrier and waterproof layers).
20-Apr Finish putting the layers (drainage, filter layers, growing media and planting).
27-Apr Verify functionality (check if the plants and the structure are okay and look if there is any problem). Plants seem to be adapting well. No sigs of leakage.
4-May Verify functionality (check if the plants and the structure are okay and look if there is any problem).
11-May Verify functionality (check if the plants and the structure are okay and look if there is any problem).

Costs

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

Quantity Material Source Cost ($) Total ($)
1 Pond liner-10ft x 12ft Donated by Pierson Building Center 70.00 00.00
1 Landscaping fabric-3' x 25' Donated by Pierson Building Center 09.00 00.00
1 Soil-28L Donated By Farm 05.00 00.00
1 Growing medium-4 cubic ft Donated by Pierson Building Center 19.00 00.00
1 Wood Glue-18oz Donated byPierson Building Center 06.00 00.00
36 Stainless Steel Wood Screws Donated by Pierson Building Center 00.85 00.00
1 Wood Preserver Paint-32 oz Donated by Pierson Building Center 10.00 00.00
1 Rubber membrane-5' x 6 ' Donated by Pierson Building Center 32.00 00.00
1 Shower Pan Liner Adhesive-16oz Donated by Pierson Building Center 09.00 00.00
5 Wood Donated By Farm 00.00 00.00
8 Plants Donated By Farm 00.00 00.00
1/4 Landscape Rocks a yard Donated by Miller Farms Nursery 67.00 00.00
1 Drop cloth 9'x12' Ace Hardware 03.99 03.99
1 Paintbrush 3" poly Ace Hardware 02.99 02.99
1 Paintbrush 2-1/2" poly Ace Hardware 02.79 02.79
Total Cost $10.58

Operation

Operation
ImageStep
weeding. Step 1: These areas may need to be weeded monthly because of the lack of soil cover.
wood rot right Step 2: There is some wood exposed that was not fully covered by the pond liner therefore it has the potential to create some form of wood rot. If this becomes a problem then placing pond liner over the exposed wood should prevent any more damage from occurring.
wood rot left Step 3: There is some wood exposed that was not fully covered by the pond liner therefore it has the potential to create some form of wood rot. If this becomes a problem then placing pond liner over the exposed wood should prevent any more damage from occurring.
wood split Step 4: The wood is not align therefore there may be a chance of the wood splitting apart. Either sanding down the wood or replacing the wood panel when the situation becomes too severe.
roof leakage Step 5: Because of the way the base of the roof was built for us. It is possible that if the membrane were to be punctured there would be substantial leakage. If this is to happen replacing the membrane would be advised.
roof leakage Step 6: Because the base was stapled it has the potential to create leakage. If this becomes an issue placing another layer of the rubber membrane over it should solve the problem.
roof liner break Step 7: The sun may damage the exposed pond liner. In this case it will be easily treated by using pond liner tape for any holes that appear and may cause potential problems. It may also just be replaced with another type of material because it is almost like a free standing panel therefore it will not cause major structural damage to the roof.

Maintenance

The roof was designed specifically for low maintenance therefore the farm will have to do some weeding and if required some watering. However, side paneling was placed on the structure and that was not accounted for in the roof over hang calculations. This means that when the roof drains water the back paneling is getting wet because the structure is now extended out an extra three inches. Making sure that back paneling wood does not rot or mold is pertinent to the health of the system.

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.
  • Check back paneling if rain has fallen because it is possible the wood may rot or mold.
  • Weed if necessary. making sure to pull anything that may have a long tap root.
Monthly
  • A soil finger test.
  • Water.
  • Any weeding. Making sure to stop the growth of anything with tap-roots that may compromise the membrane.
  • Check back paneling if rain has fallen because it is possible the wood may rot or mold.
Yearly
  • Harvest succulents if desired.
  • A soil finger test.
  • Check the life of the membrane.
  • Check on any touch ups if they were done.
  • Check back paneling if rain has fallen because it is possible the wood may rot or mold.

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. And watering to check for any potential leakage. Testing also consisted of us checking on the slope of the roof. We added water once the first two layers were placed on the roof to test the gravitational flow of the water. Once we placed the lava rocks on we once again poured water on the roof to check again the slope of the roof and to get an idea of the drainage of the roof. Once the soil and plants were placed on the roof we again added more water to check once again that the slope of the roof was an adequate degree of incline.

Test
ImageStep
Test One Step 1: blahblah
Test Two Step 2: blahblah
Test Three Step 3: blahblah
Test Four Step 4: blahblah


Discussion

The maintenance of the roof and durability of the roof seem to be withstanding. The succulents planted have started to take over meaning that thus far the soil depth seems to be permit-able for the succulents.

Lessons learned

  • A lesson learned was making sure the appropriate tools were on hand at all times.
  • Maybe adding more soil, having the soil flow over would maybe make the roof more aesthetically pleasing.

Next steps

The roof has placed side panaling

Troubleshooting

We do not for see any major problems. However, for minor issues we suggest:

Problem Suggestion
Pond Liner tear/weathered Fix with pond liner tape
Membrane puncture Replacing the membrane with an uncompromising piece.
Leakage Attending to the problem immediately. If it is a membrane/liner issue replacing those pieces would be suggested. If it is because of wood rot or splitting then if possible replacing that piece of wood is advised.
Lava rocks as a soil cover If the lava rocks prove hazardous to the health of the soil and/or plants replacing the soil cover with another organic material is required.

Team

Introduce team and semester in the following format:

References

  1. 1.0 1.1 Weiler, S.K. and Scholz-Barth. 2011. "Green rood system: A Guide to the Planning, Design, and Construction of Landscapes over Structure".
  2. 2.0 2.1 Oberndorfer, Erica, Jeremy Lundholm, Brad Bass, Reid R. Coffman, Hitesh Doshi, Nigel Dunnett, Stuart Gaffin, Manfred Köhler, Karen K. Y. Liu, and Bradley Rowe. 2007. “Green Roofs as Urban Ecosystems: Ecological Structures, Functions, and Services. (Cover Story).” BioScience 57 (10): 823–33.
  3. 3.0 3.1 3.2 Dunnett, Nigel, and Noel Kingsbury. Planting Green Roofs and Living Walls. Portland: Timber Press, 2008.
  4. 4.0 4.1 Lazzarin, Renato M., Francesco Castellotti, and Filippo Busato. 2005. “Experimental Measurements and Numerical Modelling of a Green Roof.” Energy and Buildings 37 (12): 1260–67.
  5. 5.0 5.1 5.2 Peck, S. and M. Kuhn. 2003. Design Guidelines for Green Roofs (PDF) (22 pp, 551K). Canada Mortgage and Housing Corporation and the Ontario Association of Architects
  6. 6.0 6.1 "Green Roof Systems: Intensive, Semi-Intensive, and Extensive.".Architect's Technical Reference. Accessed February 8, 2015. http://www.archtoolbox.com/materials-systems/site-landscape/green-roofs.html..
  7. "Hoffmann, G., Stack, R.C. and Wye, B.V. 2012. “Stormwater Management Guidebook”.