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ICF Basements


Basement Waterproofing

Amvic ICF is an ideal product to build below grade structures. Properly waterproofed and with appropriate control of drainage, an Amvic ICF basement or daylight basement is completely dry, has no dampness, and maintains a very even temperature through the year. Proper waterproofing methods for basements


There are numerous waterproofing products on the market that will work. Amvic Building System recommends either a peel-and-stick membrane system or a liquid-applied waterproof barrier coat, that is specifically certified for use with EPS foam ICF systems.


Liquid applied waterproof systems tend to be less labor to install (fewer hours) and do a superior job of sealing at the block to foundation joint. Note: This “cold joint” is the primary suspect for future water penetration in your building. It pays to spend a bit of extra time and attention to this area.


Waterproofing membranes are not all satisfactory so please contact us to discuss. In the case of membranes a mastic to seal the edges and a primer are usually required. Many primers and mastics will dissolve the EPS, so selection of one that is certified for use with EPS foam of ICF is essential.


The waterproofing membrane must wrap the side of the footing and is installed from the footing to 6” above grade. Each strip of membrane overlaps the preceding membrane strip. The membrane must be protected from puncture by a protective mat.


Note:  The waterproofing membrane is only one element of the design necessary to waterproof and protect a below grade structure.  Generally each structure’s waterproofing system needs to be designed to carry surface water away from the foundation, to remove roof runoff with gutters and downspouts, and to intercept subterranean water with a drainage system such as drain rock and a French drain system.  In the case of a full basement where gravity drainage is not possible, then a sump and sump pump may be required.   In all cases the waterproofing membrane is the last line of defense against water …it only comes into play if the other systems failed.


The membrane must be installed as per manufacturer recommendations.


Protection for Waterproofing. Before backfilling either a protective water barrier drain fabric or a dimpled drain board is installed to provide an air barrier and protection for the waterproofing. The air barrier eliminates any hydrostatic pressure against the wall, and allows any subsurface water to drop freely to a French drain and be carried away from the structure.


Edge termination for vertical installation on concrete or masonry.


The necessary 7 elements of waterproofing:


  1. Install waterstop material into cold joint between footing and first course of ICF block.
  1. Slope surface soil away from the structure so that rainfall is carried away from the structure
  2. Install gutters and downspouts to carry roof water away from the basement walls.
  3. Install a waterproof barrier from 6” above final grade down to and onto the side of the footing or slab.
      a. Roll membrane, or
      b. Liquid-applied membrane (Amvic Pacific Prefrence)
  4. Install a perforated pipe foundation drain or “French drain” and cover it in ¾” drain rock with 12-18” of rock. Cover the rock with geotextile filter fabric. Note: There are other acceptable French drain solutions that are not nearly as common.
  5. Install a protection course and drainage mat on top of the waterproofing course, and over top of the footing drain and drain rock. A dimple drain board should be used.
  6. Backfill with native soil, IF a dimple board air barrier with a filter fabric has been installed. If no dimple board, then backfill with drain rock.


Notes on backfilling:

  1. Do not backfill a wall system until the floor above has been installed.
  2. Wait at least 2 weeks after pouring the wall-consult your engineer.
  3. Do not compact the soil until at least 30 days after pouring (and the floor system is installed).

image showing proper method of backfilling to waterproof basement

We carry a wide array of waterproofing systems… Please contact us to discuss your project.

For more information, contact Amvic-Pacific: 530-265-9085