Battle mold with proper knowledge of construction

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IN DEPTH: ENGINEERING & CONSTRUCTION

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From the February 24, 2006 print edition

From My Perspective

Battle mold with proper knowledge of construction

Josh Bhate

Special

In new construction, due to tight building delivery schedules, the

interior work often commences before the building is made weather

tight prior to installing moisture sensitive materials.

Mold growth can occur in new buildings when water infiltrates or

condenses and then remains in place on porous, cellulose building

materials. These materials are a part of the normal building

construction. Molds are found all year, indoors and outdoors in the

air and settled on surfaces. Outdoors, molds are part of nature and

they breakdown organic matter.

Mold growth within buildings or interstitial wall cavities is not

considered normal and will degrade the building materials as well as

result in future occupant health and liability problems.

Typical new construction related moisture sources and mold growth in

buildings or building envelopes fall in the following four

categories:

Improper storage or protection of construction materials. Moisture

entrapment can occur when materials get wet during storage at

manufacturer, distributor and job site, or during transport.

Moisture becoming enclosed within the building due to materials used

or installation methods. For example, if gypsum wall board is

installed during inclement weather or elevated relative humidity,

sufficient moisture may be present to enable mold growth.

Moisture infiltration caused by defective construction methods,

materials, systems design or incompatibility. Defective construction

can be related to roofing, exterior cladding, windows and doors,

structural or design aspects of the building. Improper detailing or

use of materials can also cause moisture infiltration or

condensation.

An " incident " that subjects the building to water spills from storm

or hurricane events, flooding, plumbing leaks or common spills.

Failure by the contractor's field personnel to remove water and dry

building materials within 48 hours of the initial moisture contact

is one of the most common problems of mold contamination and

colonization during new construction.

Risk into perspective

The cost of mold-related problems is expected to increase

dramatically as all of the parties involved in the construction of

new buildings come to grips with the long ranging risk management

implications of mold contamination. The mold-related claim

exclusions in commercial, residential and professional liability

insurance policies have left many involved with construction

projects virtually uninsured for mold-related damages.

Developers, contractors, owners and lenders may not have mold-

related insurance protection in their traditional insurance programs

for remediation costs, liability or property losses. The Insurance

Information Institute estimates that mold losses cost insurance

companies more than $5 billion in 2003.

The total cost is significantly more if remediation costs and

uninsured losses are considered. In addition to these concerns,

personal injury claims related to mold continue to grow.

What can be done

Prevention is always better than the cure. It is less expensive to

take measures to prevent a mold problem during construction than to

pay for one after it has occurred. The key to predicting and

controlling loss exposure is to review the structure using building

science principles as an assessment tool.

Look at the building and construction methods throughout the

construction process and document the preventive and corrective

measures taken. Confirm that no contamination is present at each

step of the construction sequence as the areas are closed in or

covered with paint, wall coverings, etc.

Such documentation would be a valuable tool to protect the

contractor and developer from future claims of construction defect

and mold contamination.

The building science-based review would provide the developer and

general contractor insight into identifying problems and monitor the

construction process aimed at avoiding mold-related problems during

construction. Future problems and losses can be minimized through

the proper operation and maintenance of the building.

Diagnostic evaluations

Research into the root causes of mold-related losses in the United

States has revealed that the relative risk of a building can vary

significantly. The variability depends on the design of the building

envelope, materials selected, local building codes and enforcement,

the quality of the craftsmanship and the region in which the

building is located.

The mold risk is gauged based on how the general contractor controls

moisture during construction and what kind of proactive testing is

completed during construction and prior to ownership. The following

are types of typical questions that should be asked during

construction and the review process:

What steps are the general contractor required to take for

protection of building materials during construction? Is there a

plan to protect the building materials in the event of abnormal

weather events?

Is there a written prevention plan to lower the risk for moisture

damage in new construction and renovation projects? Is there a

mechanism to report leakage problems with plumbing lines,

condensation accumulation or moisture intrusion at openings?

Have the owner and general contractor budgeted for drying and

humidity control particularly during the finishing stages of the

project?

Has there been a provision made for periodic inspection, testing and

documentation during construction to verify that no mold growth or

conditions suitable for mold exist in the building prior to applying

finishes or enclosing wall cavities, etc.?

How is the exterior wall designed and what level of detail is

provided in the drawings/specifications to ensure the plan is

executed? For example, in a hot and humid climate, the review would

focus on the location of the primary air and vapor barrier and

whether the exterior wall design includes any unintentional internal

vapor barriers.

HVAC assessment

The HVAC assessment focuses on whether the system has the ability to

control dew point within the building over the majority of

a " typical " year and whether the system can maintain the desired

pressurization across the entire building.

What does the owner/general contractor require of envelope testing

(windows, other critical penetrations for air/water leakage) and the

HVAC system? Well-detailed testing plans during construction and at

the end of the project prior to transfer can reveal performance

problems before the ownership is transferred.

The best designed buildings can have problems if not operated and

maintained appropriately. The moisture problems should be addressed

in a timely manner. Building diagnostic experts can provide

nondestructive testing methods such as infrared thermography to

quickly and accurately diagnose building problems.

Josh Bhate, a project manager at Bhate Geosciences Corp., is a

specialist in mold growth in new construction. He supervises the

company's building diagnostics and forensic sciences division. He

can be reached at (205) 591-7062 or by e-mail at jbhate@bhate-

geo.com.