 reinforcing so the waterproofing doesn’t flow into the gaps creating thin spots and potential weak points where tears could occur if the plywood moves.
Above Image: CIM detail for plywood joints
A reinforcing fabric is a roll of fabric that must be adhered to the surface. The fabric is usually adhered with liquid waterproofing. When the initial coat of waterproofing has enough strength to hold the fabric in place, a second coat of waterproofing can be applied to the top of the fabric.
A reinforcing tape is a fabric with a sticky adhesive on one side. The tape can be stuck into place and does not require the initial coat of liquid waterproofing. The cost associated with tape is typically less than fabric due to the speed at which it can be applied. When comparing costs, it is important to factor in the price of the initial coat of waterproofing needed for fabric.
There must be no wrinkles or fish-mouths present in the tape or the fabric. If any exist after the system is dried/cured, they must be cut out and properly repaired. Wrinkles and fish-mouths provide small tunnels through which water travels, reaches the gaps in materials, and continues, using the path of least resistance.
Trowel Grade Mastic, Caulking, Backer Rod and Bond Breakers
A trowel grade mastic product is a viscous liquid-applied material that can be used over sharp edges to assure proper thickness or to fill in gaps and cracks prior to installing a waterproofing system. The product may come in pails, cans or caulking tubes.
Expansion joints, large cracks and voids may need to be filled with foam backer rods and then topped off with trowel grade or caulking material. This is typically necessitated where movement is expected. Using a foam backer rod followed by trowel grade or caulking material will maximize the life of the sealant in the gap.
Moving joints requiring backer rods and sealants, such as trowel grade mastic or caulking, may also call for the use of a bond breaker over the sealant. The purpose of a bond breaker is to prevent the waterproofing from bonding to the sealant so that it can expand and contract within the material’s limits without tearing or breaking. The drawing below illustrates how all these components can be used together to create a robust waterproof seal. (insert expansion joint detail drawing picture)
Image above: How all these components can be used together to create a robust waterproof seal
Other System-Specific Flashing Materials
Certain systems utilize uncured neoprene flashings or metal flashings to achieve results similar to those provided by reinforcing fabrics or tapes.
Taking the following steps to create proper seals will dramatically reduce the potential for leakage:
- Identify detail conditions.
- Review details with waterproofing manufacturer.
- Ask for standard and nonstandard detail drawings that illustrate proper techniques.
- Obtain the necessary accessory products.
- Execute carefully! Take extra time to install the system over details. Defects in the details almost always result in leaks.
If you still have questions, you can always contact us