Contents
- 1 Estimate design, installation, and maintenance costs
- 2 Design steps
- 2.1 Determine project budget
- 2.2 Assemble a design team
- 2.3 Establish goals
- 2.4 Conduct lifecycle cost analysis
- 2.5 Determine project timeline
- 2.6 Determine green roof financial incentives available for project site, such as, for example, stormwater utility fee credits or grants.
- 2.7 Site analysis
- 2.8 Design green roof
- 3 Design steps
- 3.1 Determine project budget
- 3.2 Assemble a design team
- 3.3 Establish goals
- 3.4 Estimate design, installation, and maintenance costs
- 3.5 Conduct lifecycle cost analysis
- 3.6 Determine project timeline
- 3.7 Determine green roof financial incentives available for project site, such as, for example, stormwater utility fee credits or grants.
- 3.8 Site analysis
- 3.9 Design green roof
- 3.10 Site analysis
- 3.11 Design green roof
- 3.12 Determine type of green roof desired based on goals, constraints, and budget
- 3.13 Design green roof
Estimate design, installation, and maintenance costs
The information in this section is not intended to be a comprehensive green roof design manual. The main goals of this section are to provide examples of issues to consider when designing a green roof, as well as factors that will affect stormwater treatment performance.
References that address green roof design include the following.
- ANSI/SPRI RP-14 Wind Design Standard for Vegetated Roofing Systems
- ANSI/SPRI VF-1 External Fire Design Standard for Vegetative Roofs
- ANSI/GRHC/SPRI VR-1 Procedure for Investigating Resistance to Root Penetration on Vegetative Green Roofs
- Cantor, S. L. 2008. Green Roofs in Sustainable Landscape Design. W.W.Norton, NY.
- Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (FLL) Richlinien für die Planung, Ausführung and Plege von Dachbegrünung (Guideline for the Planning, Construction and Maintenance of Green Roof –Green Roofing Guideline: developed by the German Research Society for Landscape Development and Landscape Design), latest English Edition
- [1]
- Green Roofs Tree of Knowledge (TOK): database on research and policy related to green roof infrastructure at
- Green Roofs for Healthy Cities and The Cardinal Group. 2006. Green Roof Design 101: Introductory Course. Second Edition Participant’s Manual.
- Green Roofs for Healthy Cities. No publication year given. Green Roof Infrastructure: Design and Installation 201.
- [ http://livingarchitecturemonitor.com/ Living Architecture Monitor, A Quarterly Green Roofs for Healthy Cities Publication].
- Mandel, L., 2013, EAT UP; The Inside Scoop on Rooftop Agriculture
- National Institute of Building Sciences. Whole Building Design Guide
- Snodgrass, E.C., and L.L. Snodgrass. 2006. Green Roof Plants. Timber Press, Portland OR.
- Snodgrass, E.C., McIntyre, L, 2010, The Green Roof Manual
- Weiler, S.K., Scholz-Barth, K., Green Roof Systems
- Dunnett, N., and N. Kingsbury. 2004. Planting Green Roofs and Living Walls. Timber Press, Portland OR.
Readers can also consult with a professional skilled in green roof design for design guidance.
Design steps
A typical progression for design of a typical green roof consists of the following 12 steps.
- Determine project budget
- Assemble design team
- Establish goals
- Estimate design, installation and maintenance goals
- Conduct lifecycle cost analysis
- Determine project timeline
- Determine green roof financial incentives available for projet site, such as stormwater utility fee credits or grants
- Site analysis
- Determine type of green roof desired based on goals, constraints and budget
- Design green roof
- Refine project design, installation and maintenance, and lifecyle costs based on green roof plan, specifications and detail
- Adjust design to fit budget if estimated capital or maintenance costs exceed budget.
These steps are explained in greater detail below. Adjust these steps as needed to suit your project. Some projects will not need all these steps, some projects may need additional steps, and the order may need to be changed for some projects.
Determine project budget
Project budget will be crucial to inform project feasibility and design. Design decisions that can be greatly affected by the project budget, for example, are
- how deep growing medium will be,
- whether or not additional structural support is financially feasible if needed, and
- whether or not green roof will be accessible to the building occupants or the public. This initial project budget should be updated at strategic points during the design process.
Assemble a design team
The following table shows roles of various players that can be involved in green roof design and construction. Assemble a team to fit project budget and goals, and level of complexity. Depending on the project, additional roles not shown in the table may also be needed.
Establish goals
Project goals can include, for example:
- Specific stormwater management goals
- Aesthetic goals
- Research and monitoring goals
- Specific uses, such as, for example, food production, gathering spaces
- Minimize building energy usage for heating and cooling
- Wildlife habitat goals
- Marketing and branding as part of an overall green building strategy
- Green building certification, eg. LEED or B3
Conduct lifecycle cost analysis
Determine project timeline
The ideal window for planting green roofs in Minnesota is from after last frost until four weeks before first frost. Planting during extremely hot weather, above 90 F degrees or so, generally has long term negative impacts on plant health and should be avoided. Other issues to consider are discussed in the section on construction sequencing.
Determine green roof financial incentives available for project site, such as, for example, stormwater utility fee credits or grants.
Site analysis
Evaluate factors that affect roofing design, such as, for example:
- Climate and microclimate: sun and wind exposure, precipitation, proximity to and reflection from glass curtain walls
- Type and condition of existing waterproofing, deck, and parapet if retrofit
- Roof slope (see 10 A for implications of roof slope)
- Dead and live load structural capacity
- Views of the roof
- Access points
- Roof height
- Roof drain locations and type
- Building HVAC systems; including, for example, nature of intakes and exhausts onto the roof surface and presence of condensate releases; potential impacts on vegetation; impact on potential building heating and cooling energy savings
- Water storage and supply; spigot and tap availability
- Opportunities for rainwater harvesting and storage
- Source of power if needed for irrigation or installation
- Elevations of existing or planned parapets, door thresholds, sills of curtain walls.
- Building code and insurance requirements
- Criteria presented by LEED, Sustainable Sites Initiative, Passive House, Living Building Challenge, etc.
===Determine type of green roof desired based on goals, constraints, and budget===The following table describes characteristics of extensive, semi-intensive, and intensive green roofs. In summary, intensive green roofs typically have slightly higher stormwater volume benefits, but also have higher installation and maintenance costs, and require more structural capacity compared to semi-intensive and extensive green roofs.
Design green roof
References that address green roof design include the following.
- ANSI/SPRI RP-14 Wind Design Standard for Vegetated Roofing Systems
- ANSI/SPRI VF-1 External Fire Design Standard for Vegetative Roofs
- ANSI/GRHC/SPRI VR-1 Procedure for Investigating Resistance to Root Penetration on Vegetative Green Roofs
- Cantor, S. L. 2008. Green Roofs in Sustainable Landscape Design. W.W.Norton, NY.
- Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (FLL) Richlinien für die Planung, Ausführung and Plege von Dachbegrünung (Guideline for the Planning, Construction and Maintenance of Green Roof –Green Roofing Guideline: developed by the German Research Society for Landscape Development and Landscape Design), latest English Edition
- [2]
- Green Roofs Tree of Knowledge (TOK): database on research and policy related to green roof infrastructure at
- Green Roofs for Healthy Cities and The Cardinal Group. 2006. Green Roof Design 101: Introductory Course. Second Edition Participant’s Manual.
- Green Roofs for Healthy Cities. No publication year given. Green Roof Infrastructure: Design and Installation 201.
- [ http://livingarchitecturemonitor.com/ Living Architecture Monitor, A Quarterly Green Roofs for Healthy Cities Publication].
- Mandel, L., 2013, EAT UP; The Inside Scoop on Rooftop Agriculture
- National Institute of Building Sciences. Whole Building Design Guide
- Snodgrass, E.C., and L.L. Snodgrass. 2006. Green Roof Plants. Timber Press, Portland OR.
- Snodgrass, E.C., McIntyre, L, 2010, The Green Roof Manual
- Weiler, S.K., Scholz-Barth, K., Green Roof Systems
- Dunnett, N., and N. Kingsbury. 2004. Planting Green Roofs and Living Walls. Timber Press, Portland OR.
Readers can also consult with a professional skilled in green roof design for design guidance.
Design steps
A typical progression for design of a typical green roof consists of the following 12 steps.
- Determine project budget
- Assemble design team
- Establish goals
- Estimate design, installation and maintenance goals
- Conduct lifecycle cost analysis
- Determine project timeline
- Determine green roof financial incentives available for projet site, such as stormwater utility fee credits or grants
- Site analysis
- Determine type of green roof desired based on goals, constraints and budget
- Design green roof
- Refine project design, installation and maintenance, and lifecyle costs based on green roof plan, specifications and detail
- Adjust design to fit budget if estimated capital or maintenance costs exceed budget.
These steps are explained in greater detail below. Adjust these steps as needed to suit your project. Some projects will not need all these steps, some projects may need additional steps, and the order may need to be changed for some projects.
Determine project budget
Project budget will be crucial to inform project feasibility and design. Design decisions that can be greatly affected by the project budget, for example, are
- how deep growing medium will be,
- whether or not additional structural support is financially feasible if needed, and
- whether or not green roof will be accessible to the building occupants or the public. This initial project budget should be updated at strategic points during the design process.
Assemble a design team
The following table shows roles of various players that can be involved in green roof design and construction. Assemble a team to fit project budget and goals, and level of complexity. Depending on the project, additional roles not shown in the table may also be needed.
Establish goals
Project goals can include, for example:
- Specific stormwater management goals
- Aesthetic goals
- Research and monitoring goals
- Specific uses, such as, for example, food production, gathering spaces
- Minimize building energy usage for heating and cooling
- Wildlife habitat goals
- Marketing and branding as part of an overall green building strategy
- Green building certification, eg. LEED or B3
Estimate design, installation, and maintenance costs
Conduct lifecycle cost analysis
Determine project timeline
The ideal window for planting green roofs in Minnesota is from after last frost until four weeks before first frost. Planting during extremely hot weather, above 90 F degrees or so, generally has long term negative impacts on plant health and should be avoided. Other issues to consider are discussed in the section on construction sequencing.
Determine green roof financial incentives available for project site, such as, for example, stormwater utility fee credits or grants.
Site analysis
Evaluate factors that affect roofing design, such as, for example:
- Climate and microclimate: sun and wind exposure, precipitation, proximity to and reflection from glass curtain walls
- Type and condition of existing waterproofing, deck, and parapet if retrofit
- Roof slope (see 10 A for implications of roof slope)
- Dead and live load structural capacity
- Views of the roof
- Access points
- Roof height
- Roof drain locations and type
- Building HVAC systems; including, for example, nature of intakes and exhausts onto the roof surface and presence of condensate releases; potential impacts on vegetation; impact on potential building heating and cooling energy savings
- Water storage and supply; spigot and tap availability
- Opportunities for rainwater harvesting and storage
- Source of power if needed for irrigation or installation
- Elevations of existing or planned parapets, door thresholds, sills of curtain walls.
- Building code and insurance requirements
- Criteria presented by LEED, Sustainable Sites Initiative, Passive House, Living Building Challenge, etc.
===Determine type of green roof desired based on goals, constraints, and budget===The following table describes characteristics of extensive, semi-intensive, and intensive green roofs. In summary, intensive green roofs typically have slightly higher stormwater volume benefits, but also have higher installation and maintenance costs, and require more structural capacity compared to semi-intensive and extensive green roofs.
Design green roof
Site analysis
Evaluate factors that affect roofing design, such as, for example:
- Climate and microclimate: sun and wind exposure, precipitation, proximity to and reflection from glass curtain walls
- Type and condition of existing waterproofing, deck, and parapet if retrofit
- Roof slope (see 10 A for implications of roof slope)
- Dead and live load structural capacity
- Views of the roof
- Access points
- Roof height
- Roof drain locations and type
- Building HVAC systems; including, for example, nature of intakes and exhausts onto the roof surface and presence of condensate releases; potential impacts on vegetation; impact on potential building heating and cooling energy savings
- Water storage and supply; spigot and tap availability
- Opportunities for rainwater harvesting and storage
- Source of power if needed for irrigation or installation
- Elevations of existing or planned parapets, door thresholds, sills of curtain walls.
- Building code and insurance requirements
- Criteria presented by LEED, Sustainable Sites Initiative, Passive House, Living Building Challenge, etc.
===Determine type of green roof desired based on goals, constraints, and budget===The following table describes characteristics of extensive, semi-intensive, and intensive green roofs. In summary, intensive green roofs typically have slightly higher stormwater volume benefits, but also have higher installation and maintenance costs, and require more structural capacity compared to semi-intensive and extensive green roofs.
Design green roof
- Climate and microclimate: sun and wind exposure, precipitation, proximity to and reflection from glass curtain walls
- Type and condition of existing waterproofing, deck, and parapet if retrofit
- Roof slope (see 10 A for implications of roof slope)
- Dead and live load structural capacity
- Views of the roof
- Access points
- Roof height
- Roof drain locations and type
- Building HVAC systems; including, for example, nature of intakes and exhausts onto the roof surface and presence of condensate releases; potential impacts on vegetation; impact on potential building heating and cooling energy savings
- Water storage and supply; spigot and tap availability
- Opportunities for rainwater harvesting and storage
- Source of power if needed for irrigation or installation
- Elevations of existing or planned parapets, door thresholds, sills of curtain walls.
- Building code and insurance requirements
- Criteria presented by LEED, Sustainable Sites Initiative, Passive House, Living Building Challenge, etc.
Determine type of green roof desired based on goals, constraints, and budget
The following table describes characteristics of extensive, semi-intensive, and intensive green roofs. In summary, intensive green roofs typically have slightly higher stormwater volume benefits, but also have higher installation and maintenance costs, and require more structural capacity compared to semi-intensive and extensive green roofs.