An architectural wonder known for its “dancing” water gardens at the base of a dramatically sculpted office tower of reflective glass, Fountain Place in Dallas, Texas, has always been structurally sound. However, when it was time for its famed water features to be renovated, the building’s ownership group and primary engineer wanted to be confident that the restoration would be leakproof well beyond the waterproofing materials used in its original construction.
The water garden renovation was complicated by a couple of factors.
“The water gardens were originally constructed above a parking garage with thousands of concrete cold joints, using separate pours not really designed to be waterproof,” says Gary Bennett, owners’ group representative of Fountain Place. “The vertical to horizontal concrete components were sealed with various waterproofing products that were not completely designed for the condition in how they were used.”
As a solution, they turned to a new breed of seamless, flexible coatings that, used in combination, is designed to prevent water leakage, provide chemical and UV resistance, and enhance aesthetics for decades.
The renovation project consists of nearly two acres of cascading waterfalls, pools, fountains and elevated walkway pavers.
John Pierce, executive vice president of Mobile Enterprises, notes that the elastomeric coatings had been primarily used to waterproof the water features. However, these had deteriorated over time, leading to water leaking into the parking garage below.
“The original design used polyurethane-based elastomeric coatings over 20 years ago,” says Pierce. “While these have UV-resistant topcoats, over time exposure to chlorine in the water as well as outdoor UV rays begin to bake those membranes. They become soft and chalky. They wear out, become susceptible to substrate movement and prone to leaks.”
Any water-feature waterproofing must also accommodate daily and seasonal temperature changes, since this can cause concrete substrate movement, leading to leakage over time too, says Pierce. Some of the pools above the parking garage had been remediated with PVC roofing membrane with heat-welded seams, but still had leakage issues.
“Most waterproofing materials with heat-welded seams must remain fully adhered to the substrate,” says Pierce. “However, moisture in the concrete can diminish the membrane’s adhesion, leading to gaps and water leakage. This is one reason that a seamless system is often preferred over a seamed system.”
Many traditional materials like plaster, epoxy or tile need to have an underlying elastomeric membrane to function because anything rigid would crack and leak, notes Pierce. Being continuously submerged and not chemical resistant can also cause problems to the underlying membranes.
The group decided to go with an elastomeric polyurea basecoat and topcoat combination from VersaFlex, a global supplier of high-performance polyurea coatings, liners and joint sealants, as the waterproofing solution. The spray-applied polyurea basecoat creates a seamless, waterproof, durable protective liner that stops leaks and strengthens the integrity of the entire structure. It exhibits superior physical properties such as high elongation, crack bridging, hardness and tensile strength to create a robust, resilient, puncture-resistant liner. It is also designed to withstand wide variations of temperature and humidity, including decades of freeze-thaw cycling.
“It is flexible enough to accommodate structural garage movement, ground movement, as well as daily or seasonal expansion or contraction due to temperature changes,” says Pierce. “Anytime you deal with concrete, you deal with cracks, so its crack-bridging properties are also important.”
Del Williams is a technical writer based in Torrance, California.
Disclaimer: The statements and opinions expressed in this blog post are those of the author or authors and do not necessarily reflect the position or opinion of Concrete Decor magazine.