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Below Grade Waterproofing Membrane


SKU MM-HDPE-18-30-100

Our below grade waterproofing membrane is made in the USA from High-density polyethylene (HDPE). It is available in various sizes and thicknesses. The thicknesses range from 30 mil to 100 mil ( a mil is a 1,000th of an inch). Roll heights range from 10” to 60” with the lengths mainly being 100’ with a few rolls being 80’ in length.

Our HDPE is waterproof, UV resistant, and non-biodegradable. The plastic is also resistant to insect and rodent damage, will not rot/mildew and is commercial grade. Multiple rolls of HDPE can be connected using the double sided HDPE seam tape.
In the above Picture 2: The barrier was installed a few inches away from the foundation wall to allow for a an occasional visual inspection to ensure that water was not flowing around the barrier and pooling against the foundation wall.

This material is stocked in Kansas City and typically ships within one business day.

Material Thickness:
30 mil = 1/32”
40 mil = 3/64”
60 mil = 1/16”
80 mil = 5/64”
100 mil = 3/32”

Note: Our HDPE plastic is only available in roll widths up to 60 inches.

Please note that we are unable to provide custom roll lengths.

Product Info

  • Model: HPDE
  • Material: High Density Polyethylene (HDPE)
  • Size: Various
  • Free Shipping
  • Need a written quote? Request Online
  • Questions?  Call (800) 604-5537

Product Benefits

  • Waterproof
  • Commercial Grade
  • UV Resistant
  • Non-Biodegradable
  • Will Not Rot or Mildew
  • Resistant to Rodent and Insect Damage
  • 100 Year Material Lifespan
  • Made in the USA


  • All HDPE rolls ship for free (standard ground, see map)
  • Call: (800) 604-5537 for pricing and shipping questions.

    Shipping estimates shown on the map pertain to this specific product only. HDPE orders typically ship same day if the order is placed before 12:00 noon CST. Transit times displayed in the map are listed in business days, and are approximate. Transit times are subject to stock levels at regional warehouses.  The day that the order is shipped is not counted as a transit day.

    Stratagrid Shipping Map
    HDPE Seam Tape
    HDPE Seam Tape

    HDPE Seam Tape

    Flood Basement

    Water Intrusion in Basement

    The Guide To Waterproofing Your Basement

    Knowing how to properly waterproof your basement is imperative to prevent future problems. Water leaking into your basement can lead to extensive damage if you do not address it right away. You should use certain products when the issue comes from outer walls. Here is a guide to help you take care of the problem the right way to protect your basement and foundation.

    Bore Down To The Base Of The Foundation

    First off, to protect your basement from water, you must dig all the outer perimeters of the basement down to the base of the foundation. Using the right products over the walls will be important for creating a successful waterproofed basement.

    You need to install drain tiles, gravel or crushed stone drains, perforated pipe, or other approved systems or materials at or below the area to be protected so the water can be discharged by gravity or other mechanical methods into an approved drainage system.

    Look For Cracks

    After you have completed the digging, clean the walls and look for any cracks or areas causing water to leak through. If you have found issues, apply a coat of hydraulic cement to the walls to prevent further leaking. Hydraulic cement will start to expand as it cures and its chemical properties will fill in the cracks and gaps to reduce the chance of future leaking.

    Apply A Sealant

    You need to apply a coat of cement-based sealant to all the exterior walls. Cement-based sealants are very easy to apply and can be used over concrete and masonry surfaces. This kind of sealant will harden and close off the concrete pores. If there was a hairline crack that went unnoticed in the previous steps with hydraulic cement, it will be taken care of during this procedure.

    Apply The Membrane

    Installing a heavy coat of waterproofing membrane which is an asphalt-modified polyurethane material can be trowled or sprayed on to seal the foundation preventing water from coming in from outside. Elastomeric membranes are made of modified asphalt and offer excellent waterproofing features.

    One of the most important benefits of elastomeric membranes, they are flexible and will move to help stop new cracks that might pop up. Just make sure to use a waterproofing product, not a damp-proofer product which will probably not work.

    Another option is to install a plastic waterproofing membrane which can be placed next to the foundation wall to divert the water into the drainage system. This is a good approach if applying a sealant directly to the wall is not convenient to access.

    Outside of Basement

    Backyard with Basement

    Install A Drainage Mat

    Install a drainage mat with molded dimples. The material must create air gaps between the wall and itself so moisture can travel to the drain structure. Be sure the drainage mat is cut to the exact depth of the foundation. It can help ease the lateral pressure against the foundation.

    The French Drain

    Installing a French drain or weeping tile, a pipe of 4 inches can be used and installed at the base of the footing weeping the water level below the basement floor. It's a good idea to install cleanouts to offer easy access for maintenance purposes.

    Backfill with gravel and complete the installation of the French drain. Gravel should be 18 inches from the grade for soil areas and 4 inches from the grade where cement will be poured.

    Installing Below Grade Waterproofing

    Below Grade Waterproofing Installation

    What You Should Not Do

    Read through the following to learn what not to do when waterproofing your basement:

    Do Not Use Tar

    Tar will eventually become brittle and will start to crack.

    Do Not Use Limestone To Backfill

    Limestone can limit the ability for drainage and could clog all drainage structures. You should use gravel.