September 26, 2002
Urbanization demands better quality housing
By BRIAN BRAND and TOM FRYE JR.
The rapid transformation of the Seattle metropolitan area over the last 10 years has brought exciting change as well as controversy.
Increased population and growth management has resulted in a more urban environment, bringing with it increased demand for multi-family housing at all price levels. In recent years, it has also brought an alarming wake-up call to the building industry.
The trend of finding quicker ways to meet the demand for housing resulted in a rash of building failures throughout the Northwest. In fact, many believe construction quality issues have achieved crisis proportion.
With the squeeze on supply driving up land costs and municipal processing fees, many developers opted for inexpensive materials, structural systems and labor costs in order to be competitive in the fast-paced sales market.
Then came the slowing economy with its pressure towards lowering costs in general. Now we are seeing the aftermath of this short-term ROI approach to building density. There are almost as many failing buildings covered in scaffolding and visqueen as there once were new buildings under construction.
We have learned that most buyers simply were not knowledgeable when it came to recognizing the construction integrity of a building. They couldn’t see what constituted the envelope, and buying decisions were often based on short-term considerations, such as immediate affordability. Consumers naturally assumed that what they were buying had structural integrity and would withstand the wet climate. The irony is that people who purchased lowest-cost housing were the least able to afford the often huge cost of repairing the problems that surfaced years later.
There are numerous factors contributing to these building failures. In the Northwest, the leading destroyer of a building’s integrity is water intrusion.
The wet and rainy climate of our region makes buildings here especially susceptible to water damage over time. This is especially true in multi-family projects where windows, doors, vents, and other areas can allow moisture to enter.
Multi-family housing is usually wood frame construction, and, although more affordable than concrete or steel, it has the least integrity when it comes into contact with water. Many of these high-density housing projects, built to four or five stories, are especially vulnerable to water damage, as their height leaves them exposed to high wind pressures.
Roof overhangs generally protect only the top portion of the building, resulting in more exposure to weather over the exterior. Further exacerbating the problem, recent state energy codes require tighter construction to reduce heat loss. This means that any water that gets in can become trapped, causing extensive damage over the long term.
If a wood-frame building is poorly constructed and doesn’t have adequate provisions for shrinkage and settlement, the problem becomes even worse. Product failure also happens frequently because manufacturers make exaggerated claims about a product’s integrity.
The sensible solution requires, foremost, knowledge of what it takes to construct a building correctly. This means more accountability on the part of developers, architects, engineers and contractors. Secondly, owners and developers need to realize that spending more money initially on quality construction and knowledgeable consultants is going to be more cost effective than repairing poorly constructed buildings.
Higher quality structural materials like concrete and steel, although more costly and labor intensive initially, have a much higher tolerance to impending water intrusion. Other benefits include improved fire ratings, improved strength and seismic integrity, and better sound insulation.
To avoid water intrusion in the Northwest climate, backup drainage systems must be employed. Water often finds its way in behind siding systems. Membranes placed between exterior siding and walls, with proper flashing, provide an unobstructed path for water to escape without causing structural deterioration.
Better materials used with exterior cladding systems are also essential to the integrity of a building. And, possibly the most critical key to a building’s integrity is to hire experienced architects, engineers and general contractors, as well as a waterproofing consultant to assist from design through construction, to ensure the project is built properly.
Several local projects have utilized high-quality materials and systems to ensure longevity. The Palazzo II, an urban mixed-use building in downtown Bellevue, consists of four stories of stacked multi-family units over one story of office and one story of retail.
The building is constructed of post-tensioned concrete frame with a “window wall” cladding system. This system includes walls, cladding and windows made and installed by the same manufacturer. The panels are engineered and prefabricated by one manufacturer, eliminating the need for a wall assembled by multiple subcontractors, which in turn improves quality assurance.
The window wall includes internal back-up drainage systems, which allow for inevitable infiltration of water, by providing channels and weep holes to return the moisture to the exterior. These panels are constructed of powder-coated, steel-reinforced aluminum. Care was taken to coordinate construction details on glass, structure and cladding systems with the architect, contractor and subcontractors. A waterproofing consultant, experienced with this type of building and cladding system, was utilized for assistance with details through all phases of the project.
Portions of the cladding were water tested on-site to a specific ASTM standard using a specially designed device (“rain rack”) which simulates a severe rain storm by spraying water at critical joints at given rates and specific periods of time. Rooms inside are pressurized to create a negative pressure which will “pull” water in through the smallest of cracks. This test can further identify potential deficiencies in construction quality and allow the manufacturers and installers to correct these deficiencies before they become a problem.
Another medium-density housing project is The Waterford at Des Moines, a luxury condominium overlooking the Des Moines Marina. Though somewhat unique in its stacking arrangement — two levels of “flats” over a level of parking atop two-story townhomes — the building uses quality, durable materials such as a curtain wall and an aluminum sandwich panel wall system to enclose a steel-framed structure.
Due to its location on a steep bluff facing Puget Sound, a concrete base is used to secure The Waterford into the hill. The sturdy base also helps stabilize the hillside against potential landslides.
Steel provides strength, quality and durability, and the commercial-grade curtain wall system provides optimum weather protection — critical given the location and exposure to weather. To further prevent water intrusion, the building’s skin is designed with a sophisticated drainage system employing a two-layer “rain-screen” assembly to keep moisture out. A waterproofing consultant assisted through all construction phases, and utilized similar water-testing techniques as Palazzo II.
Awareness, education needed
The push for higher quality structures must come from the building industry itself. As more people become aware of the costs associated with poor quality, we can begin moving away from short-term, quick fixes and move toward quality buildings with long-term integrity.
We must continue educating the community at large, since this issue is something that affects everyone. With continued urbanization an inevitable reality, it is critical that we all recognize and support the approach of building with integrity the first time around.
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