How to keep Godzilla El Niño from dampening your day:
Hohbach-Lewin has utilized pre-cast concrete systems on numerous urban infill parking over retail facilities throughout California during the past several years and until recently the waterproofing hasn’t seen much action. Given the recent increased precipitation (see reasons to go skiing with us below), we felt the need to expound on some of the systems/challenges associated with providing reliable waterproofing for this construction type.
Typically two systems have been utilized to prevent water from intruding into the retail space.
Single Elastomeric membrane: An Elastomeric water proofing membrane/traffic coating is applied directly on top of the structural topping slab. This requires less upfront costs to install and is easier to access for maintenance. It also adds less mass to the building when compared to the alternate double slab system described below. Typical warranty time for this system is 10 years. “Soft cutting” the topping slab above the double tee joints as soon as possible after the initial concrete topping slab sets (ideally within two to three hours of the pour – before initial concrete shrinkage cracks can occur) and tooling the expansive joints in the correct manner is of paramount importance. The joint consists of a “v-groove”, so configured so the expansion joint filler adheres to the sloped sides only (and not the bottom of the groove) – this allows for some movement in the joint without damaging this critical water proofing bead.