CCAT outdoor kitchen roof

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Background

This project will be taking place at Humboldt State University’s Campus Center for Appropriate Technology (CCAT) as part of the Appropriate Technology (ENGR 305) class in Spring 2020. Our team, Under One Roof, will be working with the center's three co-directors to retrofit the roof over the CCAT Earth Oven and the CCAT rocket mass cobb bench heater in their outdoor kitchen. As you can see in Fig. 1 and Fig. 2, the existing roof is made up of two parts. One is the living roof, which seems to have been made in 2006. Learn more about that project here. The other part of the roof does not seem to have an Appropedia page, but looks like it is made up of a wooden frame with corrugated metal sheeting. We have about 12 weeks to design, prototype, and complete this project, starting the first week of February 2020. Due to our geographical location, in the small town of Arcata on the coast of Northern California, we get a significant amount of rainfall and consistently high humidity. This has to be taken into account in the design of any project built here, outdoors or indoors. This is one of the reasons why the protection of existing projects is so important. Overall, the roof should be sturdy, functional, and aesthetic.

Problem statement

The roof currently in place is not successfully protecting the existing project in the outdoor kitchen. The objective of this project is to make a long-lasting and well-designed roof to protect the cobb oven and bench, as well as to provide a demonstration of green building and the potential of appropriate technology to teach future students and community members. The goal is to create incentive to make the outdoor kitchen at CCAT usable and enjoyable regardless of weather, to prevent weathering of the current projects in the outdoor kitchen, and to ensure that they last as long as possible in order to continue making an impact on future generations, and inspire the people that visit CCAT.

Our Team

• Under One Roof: Emily Read, Valentina Acosta, Nick Brandi, Buddy Mitchell

(add team photo here)

Literature Review

This is a review of the available literature pertinent to the a specific project.

Purpose

Basics of the Roofs Purpose The purpose of this roof structure is to extend the covered area to accommodate rainfall while using the cob oven. Also the area with a larger roof can be used for a year round outdoor classroom space or recreation space. We also hope to be able to set this roof up for potential future projects such as rainwater catchment systems, living roofs, or rooftop solar.

Concerns(Purpose)

Some concerns we have for the project are being able to fill all of the accommodations we would like to achieve for this project. We and CCAT would be able to have this space cover for rain, keep all sunlight out and navigate around the large chimney there. We would also like to have an aspect of a living roof or some other set up for another AT project. This potentially could be stifled by funding or construction limitations with the space we do have.

Different Purposes the Roof Can Serve

Purpose 1: All weather Accommodations^{[1] [2] [3]}

-Precipitation Humboldt County Receives from 30 to 80+ inches of rain annually. We want to make this area residing under the roof to be accessible through any variety of weather. Currently the roof that is standing does not do this because of gaps in the roof or some areas having no cover at all.

-Sunlight With the typically cooler weather in Humboldt County California, sunlight is often desired. To optimize this we can figure out which way we could open our roof structure. Arcata California sits at a latitude of 40-51'59 N giving Humboldt a daylight factor of about 2.5. This is on the lower end, therefore to get optimal light in we can have the open areas extended as high as they can facing the sun to let in as much light as possible.

Purpose 2: Outdoor Classroom^[4] CCAT is a place where ideas of Appropriate technology are share with Humboldt State University's students and community members. CCAT offers courses and would like the space we are building to be able to accommodate an outdoor classroom year round. Outdoor classrooms have shown to have students be able to easily grasp science and math in the outside world. It shows more engagement for the environment and science. This is important for CCAT's program and message.

Purpose 3: Potential for more Appropriate Technology Projects ^[5] Building a roof at CCAT gives Humboldt State University students or CCAT the opportunity to be able to develop further appropriate technology projects. Through our construction we would like to do things that set up for the future. Roofs have the potential for things such as solar, rainwater catchment, living roofs and more. These types of projects bring people much needed solutions and will set up great opportunity for the future of Humboldt's community.

Structure

Design and common errors: ^[6]

Design is important because of the wide variety of issues that may arise with the construction of a roof in consideration to intense weather, deterioration, leaking, or overall structure failure. A good way to measure a roof’s condition is by the condition of the ridge. Wrongly sized roof rafters and structural ridge beams are commonly found errors in roof framing. Structural reliability: a probabilistic measure of a structure’s safety. ^[7]

Goals such as determining strength properties of material types, conveying a safety margin that can be used by all designers, defining design loads and load combinations (temporary loads), keeping in mind uncertainties with design practice.

Roof structures and types

Roof structures and frames change dramatically depending on the design and purpose of the roof. Basic roof components include: rafter, ridge, wall plate, and joist. Single or double roofs are less sturdy but also require less materials. They do not require ceiling joists and may not be structurally sound under pressure. Collar roofs are single roofs with additional beam placed horizontally across the two rafters. A closed couple roof includes a ceiling joist and a hanger (a beam connecting the ridge to the middle of the ceiling joist).

Terminology ^[8]

• Bulleted list item
• Roof span - distance across the roof from one wall plate to the other
• Roof height/rise - measured from top of wall plate to ridge
• Roof pitch - rise divided by the span (rise over run)
• Low-pitched roofs shed water less efficiently because of the slope
  • Standing water more likely to soak materials
• High-pitched roofs don’t let water sit because of the steep slope
  • Overlapping shingles work well in this case
• Truss - structure built with triangles to prevent bend under pressure
  • Pros/cons
    • Labor intensive and require connections
    • Economic use of construction materials
    • Lightweight pieces make for easier transport after putting it together
• Alternative trusses
  • Bamboo - potentially a local material that is strong and stiff but has to be treated to increase durability

Loads and forces - must determine construction materials to find building’s self-weight. ^[9]

• Imposed load
• Dead load
• Permanent load - it acts vertically downward
• Snow and ice load
• Wind load

Material basics

This build is relatively simple, we need to make a structure and roof to provide a dry space for people to work during the wet season. The big challenges in the build are the multiple uses of the space. The space we need to enclose has a cob oven and a barbeque under it, we need to ensure that the smoke is channeled out and does not light the structure on fire after many hot dry months. We also need to make the structure last a long time and hold up to the harsh weather conditions. Concerns: The main concerns are fire resistance, weather tolerance.

Types of Material

Telephone poles ^[10]

• Telephone poles are cheap readily available and pressure treated to withstand the toughest abuse nature sends its way. They are by far strong enough to hold up whatever we put on top of them. The poles I am talking about are typically sold as small as 20 feet long with a base width of 14 inches and top width of 12. The beauty of these is they are heavily treated with chemicals so they are resistant to insects and fungus, this is also the downside, they can off-gas or leach depending on how they were treated.

The joist and rafter ^[11]

• The Joist are what hold up the top of the rafters. These pieces are usually 2x6 but can be bigger or smaller depending on the use and needs. In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet. There is a limit to the size that we can span without bumping up the size or quantity of our support structures. [3]

The waterproofing ^[12]

• This is fairly straight forward, in the middle of the actual roof we need to have a water barrier A material to actually keep the water from seeping in.

The components of the top roof are:

• Underlayment- The Layer of tar paper or Tyvek is laid under the shingles to keep the water out. This is the part that really keeps you dry.
• Flashing- This is a part of the roof that keeps water from sneaking in where there is a vent or chimney. Flashing is a small piece of usually metal that covers the cracks where things pop out of the roof. You can use a galvanized alloy, copper, lead-coated copper or stainless steel to flash your roof.
• Shingles or Tile- ^[13] This is the outermost part of the roof, when you look at a roof this is the part you see. The main purpose of the shingles is to protect the rest of the roof from the harsh elements. These are also what you look at so they have an aesthetic value.
• Trim- This is what protects the roof at the ridge or any joint. It keeps the roof altogether and watertight.

AT: Solar Energy, Rainwater Catchment System, Living Roof

Solar Energy: Solar Energy is the conversion of heat from the Sun to energy. Solar Energy is used today in many ways such as space heating and cooling, daylighting, hot water, and cooking. The most common way to harvest heat is solar panels.

Solar Energy Concerns: Main concern for using Solar Panels is location. Arcata, California is a cloudy and wet place throughout Fall and Spring. These panels will only be collecting optimal heat at very random times of the year and throughout the Summer months.

Types of Solar Energy:^[14]

Type 1 Passive Solar Energy:^{[14] [15]}

Passive Solar heating techniques involve placing larger windows on south-facing walls and locating thermal mass, such as a concrete slab floor or a heat absorbing wall, close to the windows. Double or triple paned windows can also be used as a heat trap. It collects energy during the day and then re-radiates it at night.

Disadvantages:

• Window installation
• Thermal mass installation
• Location and Climate

Advantages:

• Cost efficient
• Natural approach
• Environmentally friendly

Type 2 Active Solar Energy: ^{[14] [15]} Active solar energy systems use the same principles as passive systems except that they use a fluid (such as water) to absorb the heat. A solar collector positioned on the roofs of buildings heats the fluid and then pumps it through a system of pipes to heat the whole building. The two major types are solar hot water fluid collectors that heat a fluid circulated within them, and air collectors that heat air to be distributed in the house with fans.

Disadvantages:

• Location and climate
• Cost efficiency
• Roof condition

Advantages:

• Cost efficient in warmer temperatures
• Environmentally friendly

Type 3 Photovoltaic (PV) Energy: ^[14] PV panels contain hundreds of small silicon cells that collect the sun’s energy and change it into electricity that can be used in a home or building, etc. PV cells are made mostly of silicon, an abundant semiconductor material (material that conducts current) in the earth’s crust. One side of the material is electrically positive, the other negative. When light strikes the positive side, the negative electrons are activated which then produce energy.

Disadvantages:

• Location and climate
• Sunlight
• Cost of Solar Panels

Advantages:

• Environmentally friendly
• Solar Energy is infinite
• Relatively cheap to create in rural areas, extends power grid

Designing interpretive materials: According to the sources used, interpretative materials for solar energy are PV solar panels, double or triple paned windows, and thermal mass such as concrete, stone flooring, and thick insulated walls

Rainwater Catchment System: ^[16] Rainwater harvesting is a system that catches the water falling from the sky to use it for human use. It is usually categorized into two systems; passive and active. A passive type uses almost no mechanical means to capture, convey, or treat the caught rainwater. An active type uses mechanical and/or electrical means to capture, convey, and/or treat rainwater. This is a great way to raise water security in communities and localize water use.

Rainwater Catchment Concerns: Concerns for this system is storage, how big of a tank do we need and where we can put it. What this water will be used for such as potable water or non-potable water. Location of the system and if it will work in the area in which it is needed. Also what materials we can use for maximum safety of water use.

Types of Systems:

Passive System:^{[16] [17]} This system uses landscape features to slow, absorb, and/or store rainwater. This type has the advantage of lower cost per volume of water.

Advantages:

• Low cost
• Low impact
• Natural approach

Disadvantages:

• Location/Vegetation
• Maintenance

Active System: ^[18] This system uses mechanical and/or electrical means to capture, convey, and/or treat rainwater. Can be categorized into two systems; dry and wet. A dry system is one in which the conveyance system (e.g., downspouts) is evacuated and dry between rains, whereas a wet system is one in which the conveyance system remains filled with water between rains.

Advantages:

• Cleaner water

Disadvantages:

• Proper filtering and storage
• Maintenance

Wet and Dry Systems: ^[16] Wet: A wet system has the advantage of being able to pipe the water underground and back up into a tank to keep the piping out of the way. Dry: A dry system has the advantage of less clogging and fewer insects.

Designing interpretive materials: According to the sources used interpretive materials for Rainwater Catchment Systems are safe catchment surface, gutters and downspouts,screens, and storage

Living Roof: A living roof is a roof covered by a waterproofing membrane and then covered partially or completely by vegetation and growing mediums that retain water and transfer it back into the atmosphere through natural means. ^[19]

Concerns for Living Roof: The climate in which this roof will be built is not optimal for growing all types of vegetation.

Advantages: ^[19]

• Maximizes use of space for gardening
• Natural approach
• Aesthetic
• Potential to grow native species plants
• Insulation
• Air Quality

Disadvantages: ^[19]

• Climate
• Space

Designing interpretive materials: According to the sources used interpretive materials for a Living Roof are a roof, thermal insulation, pond liner, root membrane, gravel, and moisture blanket

Project Evaluation Criteria

The following Criteria will be used to assess the success of this project. These criteria were chosen based on the suggestions of the project coordinator as well as the diligent students who are working on the catchment system. The scale (1-10) represents the importance level of meeting the constraint of each listed criteria.

Criteria	Constraints	Weight (1-10)
Durability	Must last ≥ 20 years. Must have structural integrity ≥ existing shed. Structure must support human weight.	10
Safety	Must not be a hazard to users during or after its construction. Roof must provide adequate ventilation.	10
Aesthetics	Must be ≥ general CCAT aesthetic.	7
AT Components/AT Potential	Project must demonstrate appropriate technology components. Project must be built to accommodate for potential future appropriate technology projects (solar panels, rainwater catchment)	6
Practicality	Must not interfere with accessibility to CCAT outdoor kitchen. The project should be easy to maintain for the duration of its lifespan.	7
Cost	Must be within budget.	3

Design

Prototyping

Footnotes