Roof & Ceiling Systems - Introduction

This section presents the most common roof and ceiling system problems and shows North American home builders how to avoid them. It does this by improving their understanding of design principles, material performance expectations and proper construction procedures.

Three main categories are presented:

These categories are discussed as they relate to structural deterioration and damage or to water leakage.

The roof constitutes the weather barrier for the attic and the remainder of the house, so it is important that it be durable. Recurring problems with such established roofing materials as asphalt shingles and wood shingles and shakes reflect the need for improved procedures. Tile and metal roofs, which are gaining in popularity, require extra care when they are designed, scheduled and installed.

Of course, good roofing structure is critical. Without a solid structure, sagging, shifting and water leakage are likely. Proper design and good workmanship provide a good base for the roofing materials, which in turn offer protection to the structural elements of the roof.

Problems with the interior ceiling finish, including sagging, wetting and the formation of mold, are also addressed. These problems can usually be traced to structural deficiencies or to problems with the roofing materials. Proper construction scheduling and control of the interior environment of the building during construction are also covered.

This section does not present all aspects of roof construction and some of the problems discussed here are more prevalent in certain parts of North America than in others, influenced either by regional construction techniques or local weather conditions. However, this section provides most of the information you will need to identify the causes of problems so that you may avoid creating imperfections during construction.

Area	Primary Consideration	Problem	Cause
Roofing Materials	Structural Deterioration And Damage	Broken asphalt shingles.	Winds can lift shingle tabs, causing them to break.
		Curled asphalt shingles	Water vapor penetration
		Deterioration of asphalt shingle surface	Sunlight and high roof temperatures can cause differential hardening of the asphalt material through the shingle.
		Shingle deformation and displacement	Improper or inadequate roof deck or improper fastening of shingles.
		Rotting of wood roofing; rusting of metal roofing	Condensation on the underside of the roofing.
		Cracked concrete or clay roof tiles	Damage by workers during construction.
	Water Leakage	Flashing Failures	Inadequate size and improper installation of flashings.
		Water penetration from ice damming	Inadequate eave protection
		Water leakage through wood roofing	Excessive exposure length, no interlay between shake courses, and improper joint locations.
		Water leakage of metal roofing	Thermal movement
Roof Structure	Structural Deterioration And Damage	Sagging Roof Sheathing	Inadequate support for the roof sheathing
		Sagging Roof Sheathing	Sheathing materials too thin to support concrete or clay tile roofing
		Sagging roof support structure around openings	Inadequate framing around openings in roof trusses and rafters.
		Roof structure sags around truss connections	Inadequate supports and poor fastening of connections,
		Sheathing panels rise up at joints, causing ridging.	Roof panels installed too tightly
	Water Leakage	Rotting of structural members and sheathing materials	Water leakage due to ice damming.
			Excessive moisture in the attic space.
			Water leakage around flashings
Interior Finish	Structural Deterioration And Damage	Wall-ceiling separation	Truss uplift
		Wavy ceilings	High humidity and water absorption by ceiling drywall.
		Wavy ceilings	Excess humidity in the house during construction.
		Wet ceilings due to attic condensation	Air leakage
		Mold and mildew growth	Excessive humidity and cold spots.

Additional information on roofs and roofing