TerraDrain® Sheet 121

TerraDrain® Sheet 121 prefabricated drains are constructed using a formed polystyrene drainage core with a nonwoven filter fabric bonded to one side. The filter fabric is bonded to each dimple to prevent soil intrusion into the flow channels while allowing water to freely enter the drain core from one side.

TerraDrain® Sheet 121 provides additional protection for soft waterproofing membranes. The high-strength polymeric film is bonded to the flat side of the drainage core to prevent membrane intrusion into the back of the dimple.

All values provided are intended for rapid comparison purposes, only. Please refer to a specific product’s Product Data Sheet (PDS) and the disclaimers therein for a detailed listing of all characteristics, associated definitions and values needed for structure design, specification compliance review and product submittal purposes. Please Download PDS for all information transfer, printing and submittal purposes.

Property Test Method English Metric


Material 1
Water Flow Rate
ASTM D4491 165 gpm/ft2 6724 Lpm/m2
Grab Tensile Strength
ASTM D4632 100 lbs 0.445 kN
CBR Puncture Resistance
ASTM D6241 275 lbs 1.22 kN
Apparent Opening Size
ASTM D4571 70 US Std. Sieve 0.210 mm
Grab Elongation
ASTM D4632 70 % 70 %
UV Resistance
ASTM D4355 70 % @ 500 hrs 70 % @ 500 hrs


Material 1
ASTM D1777 0.44 in 11 mm
Compressive Strength
ASTM D1621 15000 lbs/ft2 718 kPa
Flow Rate 2
ASTM D4716 17 gpm/ft 211 Lpm/m

  • 1   PP = Polypropylene; HIPS = High Impact Polystyrene
  • 2   In-plane flow rate measured at 3,600 psf (172 kPa) compressive load and a hydraulic gradient of 1.0.