Grass growing on the roof of the Grassfed Shed at Tule Fog Farm.
FA info icon.svg Angle down icon.svg Project data
Type Living roofs
Authors Linnea Hampe
Location Arcata, California
Status Deployed
Years 2012
Cost USD 3190
Uses gardening, barn for animals
OKH Manifest Download
Original drawing that inspired the barn.

This project is to build a barn for Tule Fog Farm in Arcata, California, while at the same time converting a brownfield into a productive space for agriculture. Most of the construction was completed in the spring of 2012 in order to accommodate for incoming litters of piglets.

The green roof provides insulation for the interior of the barn, as well as an area that animals may have access to in the future. It has also improved the appearance of the location, what used to be an eyesore has become an attractive view with a purpose. The wood used to construct this barn was all sourced locally, and labor was on a work-trade and internship basis.

Project Progression[edit | edit source]

Problem statement[edit | edit source]

The objective of this project is to provide an indoor space for pigs and goats that is protected from the weather, while also restoring a previous brownfield and improving the overall natural landscape.

Criteria[edit | edit source]

Criteria Constraints Weight (0-10)
Housing for animals Barn must house at least 10 animals at a given time 10
Waterproof roofing Roof lining must retain water and have proper drainage 9
Locally sourced or reclaimed materials Structure must use as many locally sourced or re-used construction materials 6
Functioning green roof Roof must not leak, must provide growing habitat for grasses and other plants 8
Aesthetics Must be visually appealing from house and road 5
Safety Must be safe inside and on top of roof for people and animals 10
Rainwater catchment Rain from roof must be collected and used for animal drinking water 2
Removable walls between stalls Walls must be removable between stalls to change indoor layout and provide outdoor access 3
Roof access Animals must be able to access roof for grazing 2

Literature Review[edit | edit source]

This is a review of the available literature regarding barn construction and grass roofing.

Roof Weight[edit | edit source]

Formula to calculate the weight of soil on a grass roof:

Soil Load(psf)=Soil Density(lb/ft3) x (Soil Depth (inches)/12)

Estimated Weights[edit | edit source]

Roof Gardens Intensive 100 psf live load
Landscaped Roofs Extensive 20 psf live load


Grass Roof Layers[edit | edit source]

Underneath the plants and soil, green roofs need a filter, drainage layer, and a root barrier and waterproofing (which can be combined) by using a pond-liner.[2]

Diagram of layers for a grass roof

Water Retention[edit | edit source]

Compared to conventional roofing, vegetated roofs retain significantly more storm water. A vegetated roof retains about 60% of storm water, compared to a gravel roof, which only retains about 27%. The depth of the substrate and the slope of the roof affect how much water is ultimately retained, and when the roof reached capacity, any excess water will become runoff.[3]

Barn Flooring[edit | edit source]

Most animal housing has either wooden, concrete, dirt, or gravel flooring.

Concrete Flooring[edit | edit source]

Concrete floors are relatively easy to keep clean, but they do get cold, which can be unhealthy and uncomfortable for animals. Concrete flooring also puts unnecessary strain on animals' legs. Sleeping benches can be constructed to provide opportunities for the animals to have a warmer place to sleep. Bedding or rubber mats can also be implemented to keep animals off the hard ground.[4][5]

Dirt Flooring[edit | edit source]

Bare earth floors are simple and affordable, and can have a layer of gravel over them to improve drainage. They are not as hard as concrete floors, which reduces strain on animals' legs and also provides them with a warmer place to sleep.[4]

Wood Flooring[edit | edit source]

Wooden floors can be problematic in barns or stables because the moist environment can cause them to rot out relatively quickly.[4]

Piggery Design[edit | edit source]

The building referenced in this book was built against a brick wall, with the roof sloping towards this wall. interior stalls were 3' tall and connected both to an interior walkway, as well as providing access to outside with a door in each stall.[6]

Stall Sizing[edit | edit source]

Stall Type Recommended Size
Ewe or Doe Maternity Pen 25 sq. ft.
Calf <400lbs 15 sq. ft.
Calf 400-800lbs 25 sq. ft.
Sow Maternity Pen 64 sq. ft.

[7] NOTE: Pigs that will be using this barn are about 200lbs, while most pigs, which were used to estimate these dimensions, weigh about 700lbs. Since the pigs are less than 1/3 the size of "regular" pigs, smaller pens are appropriate.

Most of these costs are not finalized since we are determining what materials we will need as we go along in building the barn, and many of them have not been acquired yet. All costs are covered by Tule Fog Farm, and we are hoping to use soil that is already on-site rather than importing it from somewhere else. The windows we will be using were also already on site before the project started.

Costs[edit | edit source]

Quantity Material Source Cost ($) Total ($)
Wood Location 2300.00 2300.00
1 Mortar Mix The Mill Yard 7.00 7.00
5 20 ft. Rebar The Mill Yard 6.00 30.00
1 Rebar Tie Wire The Mill Yard 3.00 3.00
20 Outlet Boxes Location 3.00 60.00
2 Hose Spigot Location 5.00 10.00
1 Sand/Gravel Mix for roof Location 100.00 100.00
1 16x21' Pond Liner Location 500.00 500.00
16 Windows On-Site 0.00 0.00
1 Misc. Hardware Location 200.00 200.00
1 Soil On Site 0.00 0.00
Total Cost $3190.00

Proposed Time Line[edit | edit source]

Task to be Completed Tentative Completion Date Actual Completion Date
Pour concrete for footings and to fill existing cinder block wall March 2 March 2
Wall Framing March 4 March 10
Wall Siding March 8 April 15
Roof Framing March 10 March 18
Roof Sheathing March 11 March 25
Doorways and stalls March 16 Incomplete
Windows March 17 March 25
Pond liner on Roof March 25 April 9
Gravel drainage layer on roof April 1 April 22
Soil on roof April 8 April 28

Design[edit | edit source]

The finished project will be a small timber frame barn using locally sourced Douglas-fir and reclaimed old growth redwood siding, built on an existing concrete slab and incorporating an existing cinder block wall. The barn will have a living roof with a pond liner for waterproofing, on which there might be animals grazing in the future, but right now the goal is to get the barn built in time for piglets to be born, and to get the living roof working and waterproofed.

References[edit | edit source]

  1. Jones, Matthew. Green Roof Structural Design Powerpoint. Pdf.
  2. "Green Roof Guidelines." Green Roof Guidelines.
  3. VanWoert, Nicholaus D., D. Bradley Rowe, Jeffrey A. Andresen, Clayton L. Rugh, R. Thomas Fernandez, and Lan Xiao. "Green Roof Stormwater Retention." Journal of Environmental Quality 43, no. 3 (2004): 1036-1044. (accessed February 10, 2012).
  4. 4.0 4.1 4.2 Ekarius, Carol. How to build animal housing: 60 plans for coops, hutches, barns, sheds, pens, nest boxes, feeders, stanchions, and much more. North Adams, MA: Storey Pub., 2004. 26-27
  5. Belanger, Jerome D.. Storey's guide to raising dairy goats. Pownal, Vt.: Storey Books, 2001. 52-54
  6. Halsted, Byron D.. Barns and outbuildings and how to construct them. New York: Skyhorse Pub., 2011.
  7. Ekarius, Carol. How to build animal housing: 60 plans for coops, hutches, barns, sheds, pens, nest boxes, feeders, stanchions, and much more. North Adams, MA: Storey Pub., 2004. p.6
FA info icon.svg Angle down icon.svg Page data
Part of Engr305 Appropriate Technology
Keywords barn, grassfed shed, green roof, mortar, pond liner, rebar, sand, soil, wire, wood, housing
SDG SDG11 Sustainable cities and communities
Authors Linnea Hampe
License CC-BY-SA-3.0
Organizations Cal Poly Humboldt
Language English (en)
Translations Korean
Related 1 subpages, 8 pages link here
Aliases Grassfed shed
Impact 685 page views
Created January 28, 2012 by Linnea Hampe
Modified June 18, 2024 by Felipe Schenone
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