Green Roof Waterproofing Calculator

Root barrier and membrane for vegetated roof systems.

Roof length (ft)

Roof width (ft)

Type (1=extensive, 2=semi, 3=intensive)

Roof drains

Penetrations

Parapet perimeter (ft)

Tab to move between fields

Membrane area (sq ft)

2,003

Root barrier (sq ft)1,620

Drainage layer (sq ft)1,575

Growing medium (cu yd)18.5

Saturated weight (PSF)36.7

Total saturated weight (lbs)55,000

Estimated material cost ($)$16,878.00

How to Use This Calculator

Enter Roof Length (ft) and Roof Width (ft) — the vegetated roof area to be waterproofed.
Select Green Roof Type (1=extensive/sedum, 2=semi-intensive/perennials, 3=intensive/shrubs) to set growing medium depth.
Input Number of Roof Drains, Penetrations, and Parapet Perimeter (ft) requiring special flashing treatment.
Review Membrane Area (sq ft), Root Barrier (sq ft), and Growing Medium (cu yd) to develop material quantities.
Check Saturated Weight (PSF) and Total Saturated Weight (lbs) to verify the structural system can support the assembly.
Use Estimated Material Cost for budgeting — note that labor and structural upgrades are additional.

How the result changes with Roof length (ft)

Roof length (ft): Length of the green roof area.
Roof width (ft): Width of the green roof area.
Type (1=extensive, 2=semi, 3=intensive): 1 = Extensive (sedum, 2-6 in. media). 2 = Semi-intensive (perennials, 6-12 in.). 3 = Intensive (shrubs/trees, 12+ in.).
Roof drains: Number of roof drain assemblies requiring special flashing.
Penetrations: Pipes, vents, and other penetrations through the membrane.
Parapet perimeter (ft): Linear feet of parapet walls requiring membrane turn-up.

Membrane area (sq ft): Total waterproofing membrane including flashings and 12% waste.
Root barrier (sq ft): HDPE or copper-laminated root barrier area.
Drainage layer (sq ft): Dimpled drainage mat or geocomposite area.
Growing medium (cu yd): Volume of lightweight growing medium needed.
Saturated weight (PSF): Fully saturated dead load in pounds per square foot for structural design.
Total saturated weight (lbs): Total weight of saturated green roof assembly.
Estimated material cost ($): Materials only — membrane, root barrier, drainage, filter fabric, and growing medium.

Identify Input Parameters
4 parameters
Roof length (ft) = 50, Roof width (ft) = 30, Type (1=extensive, 2=semi, 3=intensive) = 1, Roof drains = 4 = 6 input(s) provided
Calculate Membrane area
Membrane area = totalMembraneArea * 1.12
2003 = 2003
Calculate Root barrier
Root barrier = roofArea * 1.08
1620 = 1620
Calculate Drainage layer
Drainage layer = roofArea * 1.05
1575 = 1575