What is an Exterior Waterproofing Membrane?

Foundation waterproofing

Water coming over the top of the foundation, through a masonry foundation wall (brick, stone or concrete block), through a porous concrete foundation or if your basement is nicely finished are all reasons an exterior waterproofing membrane may be the best solution to keep your basement dry as crack injections are not applicable in these cases.

An exterior waterproofing membrane is a coating that is applied to the exterior of the foundation. It is intended to stop water before it has a chance to pass over or through the foundation wall. This eliminates the damage the water can cause to the foundation wall itself as well as other components of the building or personal belongings if your basement or crawlspace is finished or used for storage.

How is an Exterior Waterproofing Membrane Installed?

Installation of an exterior waterproofing membrane is relatively straightforward once the problem is properly diagnosed. If the issue is water coming over the top of the foundation, minimal excavation is required, the membrane only needs to be applied to six inches below the top of the foundation. If the problem is water passing through a masonry foundation wall or porous concrete wall, full excavation to the footing depth is typically required.

The process to install an exterior waterproofing membrane includes:

  • Removal of any obstructions such as decks, pavers, plantings, sidewalks, patios and driveways.
  • Excavating the foundation wall to below the problem area.
  • Cleaning the foundation wall and repairing any obvious defects.
  • Installing the waterproofing membrane, we prefer a thick liquid, trowel applied version. This material needs to cure which, depending on weather can take a few hours or a few days.
  • Installing a drainage board which acts as a secondary waterproofing barrier but more importantly protects the exterior waterproofing membrane from damage when the excavation is backfilled.
  • In the case of severely saturated soil outside a foundation wall, an exterior drain tile system would be installed at the depth of the footing to carry the additional water away to a sump pump system or to daylight via gravity.
  • The trench is backfilled with the excavated material in compacted twelve-inch lifts. Once this is completed, final landscaping can be completed. Minor settlement of the excavation is to be expected.

If you have water coming over the top of your foundation or through your foundation walls, contact Midwest Waterproofing for a free consultation. Our staff can help determine where the water is coming from and which exterior waterproofing membrane application is right for your situation.