Fundamentals of Waterproofing
Structures built for commercial office space require services. What those services are and when they’re needed is what the owner of the property or his manager needs to know?
The architect knows the design details and the builder knows what he assembled. Either of those aspects of the process that ultimately put a building in your care could help define the services that are currently needed. If the architect and builder aren’t available other ways to specify the services your building needs are utilized. A few fundamentals can serve as a guide.
First is the “90% / 1% principle” which states that 90% of the problems resulting from water intrusion occur within 1% of the total exterior surface area. Another important fact about buildings that should lead to important insights is for most buildings only 30% of the total cost of ownership is in the construction, the rest is maintenance. If lack of maintenance or other factors lead to the need for remediation the ratio can be much different. For example restoring sealant before it fails will cost much less than repairing damage from the water that entered the building through the open joint.
From top to bottom, buildings need to have a waterproof:
-Roof
-Exterior Walls, the “Envelope”
-Below grade structures
Those are the three things that keep the inside of the building dry. Of course they aren’t things, they’re assemblies of things. They’re systems. Our expertise is the envelope. The system we maintain, remediate and restore includes the features, components and materials on the outside of the building from the ground to the parapet and back down the roof surface.
The Envelope as a Water Shedding System
Water channeling and diversion-
The Egyptian, Greek and Gothic architects kept the tombs, temples and castles dry with massive walls and overhangs. If wind driven rain soaked a three foot thick, solid stone wall it didn’t matter. The water could only penetrate so far. Office buildings aren’t made with huge blocks dragged to the site by slaves but water behaves the same way now as it did then. Water did, and does, flow downhill, has surface tension, behave according to capillary action, etc., so some of the features that work to exclude water from the inside of Notre Dame keep water out of the Empire State Building. Ancient and modern architecture both include building elements and features that channel and divert water.
Façade Surfaces and Materials-
The surfaces that make up the façade, both natural and synthetic, work in conjunction with water channeling and diversion features such as flashings, drip edges and weep systems to produce the envelope system that keeps water out. It keeps air and insects out too.
Water is excluded from the interfaces between building elements, by either additional elements such as flashing, or with sealants. These interfaces account for much of the area in the 90% / 1% principle.
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