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A 99% Watertight Envelope? Not Good Enough

According to construction expert Michael T. Kabul,“It is said that ninety percent of all water intrusion problems occur within 1 percent of the total building exterior surface area. That 1% comprises the various details that cover the necessary junctures and terminations of individual components. Too often, items are specified or installed without adequate thought to how they will affect envelope performance and act cohesively with other envelope components.”

Makers of watertight envelope systems often find that what works flawlessly in a research laboratory may not be as watertight as first assumed due to the imprecise conditions found on a building site; the number one solution used by builders for this fault is caulking any breaches in the building envelope. But, time is caulking’s enemy – caulking dries out, cracks, and separates. This makes ongoing building inspections a necessity over the envelope’s lifetime as water or water vapor will pierce the veneer at some time.

Water damage is a serious problem by itself, but from moisture or water vapor insidious damage can occur within the walls of your home, condominium, or place of business. This invisible damage takes the form of structural damage and the growth of dangerous mold.

The Essentials of Making a Building Watertight

To make a building waterproof the building facade, roof and foundation must be waterproof as they make up the building segments that are exposed to rain, sun, and wind – 3 of nature’s elements that cause problems for the exterior of buildings as long-term exposure leads to system fails for waterproofing.

The following are general reasons for a tight building envelope:

  • Control water vapor flow
  • Control rain penetration
  • Control heat flow
  • Control air flow
  • Control light, solar and other radiation
  • Control noise
  • Control fire
  • Provide strength and rigidity
  • Be durable
  • Be aesthetically pleasing
  • Be economical

Of course, the actual specifications for each building envelope design depends on the climate of the building project.

Waterproof Membranes

Waterproofing of building exteriors happens during construction. Between the building facade and interior walls, architects specify the waterproofing membrane they want to be installed as one of the building’s first lines of defense in keeping dry.

Building facades also use window and door systems designed to work with the building facade membrane to avoid any moisture entering at window or door frames or through the seals on them. Architects often work with membrane, window and door companies to make sure the architectural detail drawings correctly show how installation should take place.

Getting information from vendors is an important way to head off waterproofing problems before they occur.

Also during construction, the foundation is waterproofed as are terraces and things located in their envelopes. Alan Epstein, president of Epstein Engineering, PC in Manhattan says,

"The building envelope consists of the facade, roof terraces, bulkheads and anything on exterior of the building. In addition, exterior elements are backed up by interior materials. So when you’re on a terrace, typically under the walking tiles are waterproofing membranes that are part of the waterproofing system. The first line of defense is the obvious materials you see, and behind those are a series of waterproofing membranes."

Building age makes no difference in waterproof envelope issues. Older buildings tend to be improperly maintained and develop issues from exposure to weather and contaminants that are airborne (air pollution). Some newer buildings suffer leaks due to slipshod construction.

The major culprits for leaks are the roof, the facade, and terraces. Wayne Bellet, president of Bellet Construction in Manhattan explains the issues with terraces:

"The cantilevered terrace floor is a three-sided configuration. This protrusion or extension of the building’s floor is exposed on three sides: the top, the side, and the underside. It has metal reinforcement bars in it, and when moisture saturates the landing and hits the rebar, the PH rusts the metal, which then expands and displaces the concrete around it. This is one of the most delicate waterproofing matters to date."

Talk to Manufacturers of Building Envelope Moisture-Proofing Products

This post offers general information about making a building a watertight. But, there are products that help a building preserve itself besides membranes. These items include,

  • Exterior and interior coatings
  • Building design and specifications
  • Facade drainage systems

Manufacturers and distributors of waterproofing systems should be a key part of a moisture containment effort. Everyone supplying waterproofing products should know where the product is going, how it should be applied and installed as per the architect’s details.

Manufacturers carry out quite a lot of research on how well their products perform. Although new systems embracing new technology may be attractive, using products made by established manufacturers is a good bet as they have track records and reputations earned over the years. They will not go out of business and if a product fails they will help make things right.

Now that you’re on the track with the building envelope, it’s time to start thinking about stormwater management.

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