What product do you recommend for a 20x20 flat roof ( pitched 4 1/2" over 20' ) which will be planted. AKA green roof?

We recommend the using the Black Liquid Rubber Waterproof Sealant.

In this Video, you can see the process of building up a ply system. I'd recommend doing a 2 ply (each ply perpendicular) and building your final membrane on top.

Basic process will be:

1. Ensure a clean , dry surface.
2. Bridge seams, joints, gaps, vents.... with Liquid Rubber Seam Tape
3. Build your ply doing the 3 Course System of applying Black Liquid Rubber Waterproof Sealant, then 40" Geo-Textile and Black Liquid Rubber Waterproof Sealant. Do the next ply the same way but perpendicular.
4. Apply the rest of the material on top to build your final thickness.
5. Apply a weed barrier before installing your Green Roof.

For 400 sq ft, materials:

1. Calculate your linear ft for Seam Tape. Use 2" for flat seams and 4" for 90's.
2. 1 roll of 40" x 300' Geo-Textile
3. 7 - 5G pails of Black Liquid Rubber Waterproof Sealant.