Solid-roof Shade Structure Design
Design considerations for maximum effectiveness and useful life
|Roofing material||Roof material may be aluminium or white galvanised iron sheets to increase the rate of solar reflection. This should last at least 25 years.|
||For good machinery access, the roof height should be at least 3.7 metres|
|Roof pitch||Lower roof pitch results in slower air movement (e.g. 1:4 pitch or less). Steeper roof pitch results in greater air movement (e.g. 1:3 pitch is suggested for warmer climates).|
Provide a continuous open ridge to promote air movement (i.e. convective heat dissipation via the stack effect).
Recommendations for open ridge space:
50-75 mm/3.0 m of shed width (DPC et al 2009).
300 mm + 50 mm per 3 m width for sheds greater than 6 m wide for northern Australia
|Eave overhang||The recommended overhang for open-sided sheds is 900 mm. Eave overhang is dependent on feedpad/ freestall configuration, and on eave height and degree of protection required.|
|Orientation||East-west or North-south|
|Gutter and downpipe design||
As per state plumbing code (engage a qualified design engineer).
The Roof and Gutter Design Calculator has both free and paid resource for the design and construction of guttering and roof design.
Design note on roof pitch
Lower roof pitch results in slower air movement (e.g. 1:4 pitch or less). Steeper roof pitch results in greater air movement (e.g. 1:3 pitch is suggested for warmer climates).
Enclosing a shelter using sheeting, a blind or even a furled shade cloth can contribute to significant horizontal wind loads which could cause structural failure. If the angle of inclination of a roof or shade cloth is 15° or so, it will generate lift. Like an aircraft wing.
Minimise lift by either flattening the inclination of the roof to between 10 and 14° or installing it with an inclination in excess of 20°. Roof angles of 15 to 18° should be avoided.
Design note on orientation
With an east-west orientation, and an area of 2.5 to 3 m2/cow, part of the floor area under the roof will be in shade all day. Extending the floor about one third its length on both the east and west to 3 to 4 m2/cow will place feed and water troughs under shade at all times, which will encourage intakes. More dung will be dropped in the shaded area, which will need frequent cleaning to avoid the risk of mastitis.
East-west orientation, therefore, works best for concrete floors. If concrete is too costly, the north-south orientation works best.
It works well for a compacted clay or gravel floor because the sun strikes every part of the floor area under and on either side of the roof at some time during the day. This helps to keep the floored area dry and restricts pathogen build up.
A shaded area of 2.5 to 3 m2/cow is adequate if feed and water troughs are placed away from the shaded area. In regions where temperatures average 30°C or more for up to 5 hours/ day during some period of the year, the east-west orientation is deemed more suitable.
Shed profiles at 9 am, noon and 3 pm at four different times of the year.
Effluent management systems
An effective system for handling effluent and run-off is essential, otherwise cow comfort, health and production may be compromised. Refer to section 8.0 Guidelines for Victorian Dairy Feedpads and Freestalls (DPIV 2009).
Here is a list of reference material and resources specific to your state/territory.
For a more in-depth discussion on the sustainability aspects of Dairy Effluent Management, visit the Dairying for Tomorrow website.
| Federal Department of Agriculture and Water Resources
||Effluent Management Guidelines for Dairy Sheds in Australia|
| Agriculture Victoria
|Water NSW||Onsite Waste Water Systems|
| Tasmanian Department of Primary Industries, Parks water & Environment
|Queensland Department of Agriculture and Fisheries||Dairy Effluent Management Systems|
| SA Environmental Protection Agency
|WA Department of Water and Environment Regulation|
Winter and summer sunshine angles
Winter and summer sunshine angles determine how much of the floor area receives sunshine at some time during the day, given a shed is roof height and width, as below.
Note the position of water trough, grooving to help prevent cow's slipping, water run-off from the roof to lane, high eaves and pitched roof to facilitate ventilation. The shed run north-south to use sunlight to dry cow standing areas.
Note the poor drainage due to the lack of slope. The freestall shed has fans and sprinklers but is not linked to good drainage - a recipe for high mastitis levels.
This roof slope is 18° with a 500 mm vent at the apex. Eaves are 4.3 m high, and 6.9 m at apex. The shed runs north-south with 3% slope on patterned cement floor. Feed troughs are 1.2 m wide inside, 400 mm high and 100 mm thick.
Sprinklers could be fitted above head lock stalls or at the back of the cow alley in the shed.
Solid roof structures need to comply with regulatory authorities, e.g. a local council building permit is required.
|Victoria||Victorian Building Authority (VBA) has recently announced new categorisation and regulations for shade structures in Victoria.|
Regulations on Farm Structures
|VBA Regulations (new farm structure changes)|
Plumbing in Victoria
|VBA Plumbing Standards|
|New South Wales||The NSW Planning Portal provides all advice and guidance on shade structures.|
Regulations for Farm Structures
|NSW Planning Portal Shade Structure & Guidance Notes|
|Plumbing in New South Wales||NSW Fair Trading Plumbing Code|
|Queensland||QLD Department of Housing & Public Works (HPW)
HPW is a central resource for plumbing and construction in this state.
|Regulations for Farm Structures
|Plumbing in Queensland||QLD Plumbing Codes|
|Tasmania||Tasmania's Consumer, Building and Occupational Services (CBOS)|
|Regulations for Farm Structures|
|Plumbing||CBOS Technical Regulations|
|South Australia||SA's EPA is the regulatory body for farming structures|
|EPA Shelter Regulations|
|Western Australia||The Department of Primary Industries and Regional Development is responsible for regulation shade structure constructions in WA.|
|Regulations||A guide for construction & developments on land holdings in Western Australia|