Wall System House Construction

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.
	Moisture and 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.	Openings
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.
		Water penetration through wood and hardboard siding	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.
		Water penetration	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
		Water penetration through the brick veneer	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.
	Stucco	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
Drywall	Nail Pops		Wet framing lumber
	Nail Pops		Fastener pops
	Cracking	Other types of cracking	Vibration
			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
		Visible joints, ridging and tape delamination of drywall	Damaged drywall board edges
	Joints	Visible joints, ridging and tape delamination	Improper application of joint tape and compounds
			Lumber shrinkage
			Improper drywall installation
	Moisture	Deterioration of drywall in high moisture areas	Excessive humidity and dampness in bathrooms, laundry areas and exterior soffits.

Continued.......