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An Introduction To Wall Systems For House Construction

This section presents all aspects of wall systems, from the outside cladding through to the inside finish and everything in between. It highlights the prevalent wall systems problems in new North American housing, clarifies the most common causes of these problems and identifies design and construction practices that are likely to reduce the incidence of construction defects and customer callbacks. While not exhaustive, this section does address the more common construction practices in use across North America.

Moisture is the primary source of construction problems. Rain and snow leaking into wall cavities, moisture escaping from the inside of the home, and even the moisture resident in framing lumber can create a host of problems ranging from structural failure to deterioration of cladding and interior surfaces.

Good design and construction practices can eliminate these problems. Proper installation of the exterior cladding, and the use of drier lumber and an effective air barrier system are all described in this section.

Table 1 is the index detailing the topics for the wall systems section.

Table 1 - Wall Systems Index Of Topics
Area Primary Consideration Problem Cause

Moisture and Wall Systems

Moisture and Wood

Dimensional changes

Swelling and shrinkage as moisture enters and leaves the wood.

Decay caused by condensation.

Fungal growth in the cell walls of wood

Moisture and Air Leakage

The movement of ward, vapor-laden air through the wall system in winter.

Pressure differences between the interior and exterior of the building

External Moisture

Rain an snow penetration into building cladding systems.


Framing Problems

Structural Deterioration

Structural deterioration of wall-framing members and sheathing

Moisture in the wall cavity

Moisture and Wood

Wall deformation caused by shrinkage

Wet lumber

Weakened wall studs

Poor installation procedures resulting in studs being out of plumb, or weakening through excessive notching and drilling of bearing walls

Cold interior surfaces promoting condensation and growth of molds and mildew

Thermal bridging across solid elements of the wall assembly.

Windows and Doors

Operating Problems

Difficulty in operation a door or window.

Insufficient tolerances

Deflection or rotation of lintel

Warp or distortion of frame

Thermal bow

Warp of wood doors

Inadequate fastening and support of doors

Lack of final adjustment

Siding and Cladding Problems

Generic Problems

Water penetration through siding

Lack of a rain-screen wall / Incorrect installation of sheathing paper

Premature deterioration

Condensation resulting from air leakage / Inadequate drying potential

Siding deformation or displacement

Direct installation over semi-rigid insulation.

Wood and HardboardSiding

Water penetration through wood and hardboard siding

The presence of gaps in the siding and incorrect joint construction.

Poor drainage of wall elements and inadequate drips at sills or joints.

Premature deterioration

Condensation form air leakage and vapor diffusion on the back face of siding can lead to premature deterioration.

Vinyl And Metal Siding

Water penetration

Poor detailing and construction of joints between siding strips at corners and around windows and doors.

Incorrect detailing around windows and doors.

Metal and vinyl siding deformation and displacement

Poor detailing to accommodate thermal expansion and contraction.

Brick Veneer

Water penetration through the brick veneer

Improper flashing and counter-flashing installation

Inability of the wall system to shed water or to drain water from cavities.

Cracking of brick veneer

Inability of the cladding system to accommodate differential movement.

Installation of bricks during cold or wet weather.

Masonry veneer can bend and crack under wind pressures where adequate lateral support is not provided.


Moisture damage inside the wall assembly

Entry of rainwater and snow around penetrations

Entry of rainwater and snow at the junction of different cladding materials.

Entry of rainwater and snow through cracks in the stucco.

Poor aesthetic finish of wall

Poor mixing of stucco



Table 1 - Wall Systems Index Of Topics - Cont'd
Area Primary Consideration Problem Cause


Nail Pops

Wet framing lumber

Fastener pops


Other types of cracking


Shrinkage of compound

Corner bead pulling away from framing

Stresses at openings

Inadequate corner support

Visible joints, ridging and tape delamination of drywall

Environmental conditions

Damaged drywall board edges


Visible joints, ridging and tape delamination

Improper application of joint tape and compounds

Lumber shrinkage

Improper drywall installation


Deterioration of drywall in high moisture areas

Excessive humidity and dampness in bathrooms, laundry areas and exterior soffits.