By Alan Trauger

Initial thoughts may seem straightforward with a straightforward answer: durable housing is tough; its vertical and horizontal surfaces resist deterioration from weathering and use. It could be theorized that durable housing would possess three qualities.

Firmness – it is well built of solid materials.

Utility – it is useful and comfortable to its inhabitants over time.

Delight – it remains appealing from one era to another.

Durability is a key point to prevent the deterioration of structures, members, and building components over time and to maintain the safety, comfort, and health of its occupants. The question of durability, explicitly considers architecture over time. Different people will obviously appreciate and focus on different aspects of durability. Residents want to live in a pleasant and dignified place with a “good address”. Neighbors want to look at something calm and reassuring, not odd or brutal. Maintenance people hope for buildings with predictable performance and the fewest surprises and problems. Planners and politicians worry about the quality of the cityscape, the social health of neighborhoods, and the cost to public budgets.

The important aspect of durability is that buildings that are considered comfortable and attractive are somehow more worthy of the trouble of maintenance and renewal than the buildings that are not comfortable or attractive. Therefore there is a high correlation that suggests that the physical, social, and aesthetic aspects of durability are definitely related.

This Issue will focus on durability in terms of the physical attributes, longevity, and performance based requirements. The need to build efficient, sustainable, durable and cost effective buildings for the housing sector has become more important than ever. The Building Envelope Performance heavily depends upon the various agents and environmental factors that affect it’s function. Building science can be defined as the body of knowledge regarding heat, air and moisture flow in buildings resulting from these agents, and their affect on building materials and occupants. All definitions of service life and durability include references to the service environment, underscoring the key concept that durability is a function of both material and its environment, a point too often misunderstood by designers.

Longevity of housing: What is our expectation of how long houses should last? Some do-it-yourself folks build so that their “improvements” last until the house is sold to someone else. Bankers and lending institutions expect the structure to last 30 years from the time they initiate a mortgage on the structure. Serviceability could mark the end of its safe use. Catastrophic failure of a home’s structure caused by wind or earthquake will mark the end of its safe use. Green building systems are on the rise and will have consumer recognition within the next few years. Consumers are becoming aware of the impact of their purchasing decisions. More attention is being paid to renewability, sustainability, and environmental impact of the materials and systems we advocate. There are many lessons from existing housing systems; given the massive housing stock in place, there is much information to gain by making a connection between existing housing systems and new housing. We should be able to make inferences from problems witnessed and to quantify the behavior and performance of existing structures.

The effect of the do-it-yourself market is far reaching. The large retail “big box” centers send the message to most homeowners that they can do most projects by themselves. Whether the job entails painting the house to building an addition, is often seen as week-end work. Professional support for such projects will almost always result in a better job. We need to be more cautious about what we tell people they can tackle. Real estate professionals often see that projects done by homeowners can lower the value of a house compared to not making any “improvement” at all. These types of improvements are also common in the commercial sector.

Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings – newsletters.alantrauger.com.

To review authors bio, qualifications, and interest in receiving future email newsletters alantrauger.com.

By Alan Trauger

Causes For Building Envelope Failures

The majority of building envelope failures can be attributed to water in one of its many forms (gas, liquid, solid). Water degradation can take the form of biological degradation, freeze/thaw cycling or frost heave, condensation, high relative humidity (RH) levels, water ingress and absorption. Other environmental effects that are harmful to buildings are air, and its components (oxygen, nitrogen, carbon dioxide, sulfur dioxide), wind, biological and ecological agents, temperature and solar radiation.

Differential service life is a particularly important subject because it relates to the premature removal of building components simply because they are part of a system comprised of components with varying service lives. The component with the shortest life dictates the life span of the system as a whole. It is important to harmonize the service life of system components and ensure the accessibility of components for periodic maintenance, repair, and replacement.

Buildings are constructed to provide space for a function, and the functional requirements of a building typically require that the enclosed environment be controlled. The building envelope consists of those parts of the building that separate the controlled indoor environment from the uncontrolled outdoor environment. The enclosure acts as an interactive system that requires integration with the heating, ventilating, and air conditioning (HVAC) equipment, structural, architectural systems, as well as occupant comfort and loading to ensure building performance. The building envelope includes the foundation, walls, windows and doors, and roofs.

Performance requirements for the building envelope are:

• Control heat flow

• Control water vapor flow

• Provide strength and rigidity

• Control light and radiation

• Be aesthetically pleasing

• Be durable

• Control air flow

• Control rain penetration

• Control fire

• Control noise

• Be economical

WHY DO BUILDINGS DETERIORATE?

• Poor design and detailing

• Lack of buildability in design

• Lack of knowledge of materials and components used

• Lack of maintenance and repair

• Environmental effects including water related factors, biological contributors, chemical contributors

• Construction on contaminated land

• Inadequate drainage

• Movements due to settlement or temperature changes

• Normal wear and tear and users abuse

• Poor construction workmanship and inappropriate installation

Water related factors of deterioration to buildings may take the largest toll on structures- Snow, rain, moisture, internal condensation, and humidity. Biological factors include fungi, bacteria, and insects. Chemical contributors may include oxidizing agents, i.e bleach, reducing agents, i.e. sulfides, acids, i.e. bird droppings, bases, i.e lime, salts, i.e. chlorides, or even chemically neutral substances such as fat or oil. Solar radiation, air quality, freeze thaw effects and wind are other environmental contributors to building deterioration.

Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/

To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com