Building Exterior
(Building Envelope)

The building exterior shell of the home, referred to as the building envelope, is the physical structure around the controlled environment of a building (the conditioned and unconditioned spaces).

The building envelope includes:

Roof
Exterior Walls
Doors and Windows
Insulation
Weatherproofing

(The foundation is not considered a part of the building envelope.)

Building envelope defects, meaning there was a deficient design or workmanship, manifest in damage to facade components, roof leaks, low energy efficiency, and moisture problems.

Destructive Testing

Destructive testing is the most common method engineers use to evaluate the damage to a building envelope. Since many components of the building envelope are not visible, destructive testing, meaning the taking apart of building elements, is essential to evaluating a structure. It involves physically removing (tearing away) the constructed layers to view and evaluate what is underneath to find the cause of damage. In addition, the destructive testing process includes temporarily repairing the affected areas after the visual evaluation.

Common Building Envelope Conditions

Building Codes (the IBC and IRC) apply to the design and construction of the components of the building envelopes. In addition, local jurisdictions may have additional design standards that apply.

EXTERIOR MOISTURE PROBLEMS

Common causes of moisture problems of the structure’s exterior are an incorrect application of sealant, roof leaks, or faulty installation of moisture barrier material or metal flashing, which are important weatherproofing design elements. Metal flashing issues can include not being installed per plan or insufficient separation between the flashing and other building components.

Destructive testing is an investigative method used to determine the causes of exterior moisture problems.

INTERIOR MOISTURE PROBLEMS

Common causes of moisture problems of the structure’s interior are roof leaks, faulty installation of moisture barrier material or metal flashing, and condensation due to insulation or ventilation problems.

Destructive testing is an investigative method used to determine the causes of interior moisture problems.

INSULATION PROBLEMS

Insulation installation problems can be detected using an infrared camera tool. Areas that show either cold spots or hot spots are investigated through destructive testing.

GUTTER PROBLEMS

Gutters are essential because they control the drainage around a structure. If the gutter system is not functioning correctly, water can affect the building exterior, basements, crawlspaces, and foundations. Gutter problems can be associated with both design defects and problems with installation. The Building Code requires that gutters are sloped correctly to facilitate flow and adequately sized, meaning that the gutters are big enough in diameter to collect water during normal precipitation and snow melt conditions.

A common issue with gutters is that they are undersized. Gutter overflow and soil erosion along the structure's foundation can indicate a problem. It is important to understand that gutter overflow will happen during large storms but should not happen regularly throughout the year.

See more information about gutters in my blog here.

WINDOW AND DOOR PROBLEMS

Although windows and exterior doors are a part of the building envelope, structural damage to these elements, such as racking or sticky frames, which causes opening and closing problems, is more often than not caused by foundation movement.

Window and door problems can be a life-safety issue because non-functioning doors and windows may prohibit egress from the building during an emergency. Therefore, it is important that damaged doors and windows be repaired immediately by the building owner.

LEAKY ROOFS

Roof problems are commonly due to the faulty installation of flashing. It is less common in modern construction that there is a problem with the actual framing that supports the roof.

GROUND SURFACE

Siding and veneer components, such as stucco, stone, and brick, need to be properly separated from the ground. Contact with the ground exposes these components to increased moisture. An example is exterior trim or siding, which must not be in direct contact with the ground surface. This type of construction defect is very common.

LACK OF ISOLATION BETWEEN BUILDING ELEMENTS

The Building Code requires that certain building elements be separated from others by a gap of a specific width. An example is exterior trim or siding, which must not be in direct contact with concrete flatwork. This type of construction defect is very common.

The construction documents, applicable building codes, and manufacturer’s installation requirements provide the criteria for installing siding and trim as exterior wall coverings.

METAL FLASHING PROBLEMS

Metal flashing is an important weatherproofing component of a Building Envelope. The proper separation between flashing and certain building elements must be maintained. Unfortunately, construction defects related to the installation of metal flashing are common.

The construction documents, applicable building codes, and manufacturer’s installation requirements provide the criteria for installing metal flashing.