Section 8.01.06:. Roof Construction ad Covering

1. Roof Coverings. Roof coverings for all buildings shall be either fire-retardant or ordinary depending upon the fire-resistive requirements of the particular Type of Construction. The use of combustible roof insulation shall be permitted in all Types of Construction provided it is covered with approved roof covering applied directly thereto.

2. Roof Trusses. All roofs shall be so framed and tied into the framework and supporting walls so as to form an integral part of the whole building. Roof trusses shall have all joints well fitted and shall have all tension members well tightened before any load is placed on the truss. Diagonal and sway bracing shall be used to brace all roof trusses. The allowable working stresses of materials in trusses shall conform to this Code. The minimum net section of the members after framing shall be used in determining the strength on the truss at any point.

3. Attics

   1. Access. An attic access opening shall be provided in the ceiling of the top floor of buildings with combustible ceiling or roof construction. The opening shall be located in a corridor or hallway of buildings or three or more storeys in height, and readily accessible in buildings of any height. The opening be not less than 55 centimeters by 75 centimeters (22 inches by 30 inches). Seventy-five centimeters (30 inches) minimum clear headroom shall be provided above the access opening. Attics with a maximum vertical clear height of less than 75 centimeters (30 inches) need not be provided with access openings.

   2. Area Separations. Enclosed attics spaces formed of combustible construction shall be divided into horizontal areas not exceeding 230 square meters (2500 square feet) by partitions extending from the ceiling to the roof. Such partitions shall be not less than 13 millimeters (1/2 inch) thick gypsum wallboard, or 2.5 centimeters (1 inch) nominal thickness tight-fitting wood, 10 millimeters (3/28 inch) thick plywood or approved incombustible materials adequately supported. Openings in the partitions shall be protected by self-closing doors constructed as required for the partitions: Except, That where the entire attic is equipped with an approved automatic fire-extinguishing system, the attic space may be divided into areas not to exceed 700 square meters (7500 square feet).

   3. Draft Stops. Regardless of the Type of Construction, draft stops shall be installed in trussed roofs, between roof and bottom chord of trusses, in all buildings exceeding 1900 square meters (20,000 square feet). Draft stops shall be constructed as for attic area separations, and in accordance with Type of Construction.

   4. Ventilation. Enclosed attics and enclosed rafter spaces formed where ceilings are applied direct to the underside of roof rafters, shall have cross ventilation for each separate space by ventilating and openings protected against the entrance of rain. The net free ventilating area shall be not less than 1/150ths of the area of the space ventilated, except that the area may be 1/300ths this provided by ventilators located in the upper portion of the space to be ventilated at least 90 centimeters (3 feet) above eave or cornice vents with the balance of the required ventilation provide by eave or cornice vents.

4. Roof Drainage. Roofs systems not designed to support accumulated water shall be sloped for drainage.

   1. Roof Drains. Unless roofs are sloped to drain over roof edges or are designed to support accumulated water, roof drains shall be installed at each low point of the roof. Roof drains shall be adequate in size to convey the water tributary to the roof drains.

   2. Overflow Drains and Scuppers. Where roof drains are required, overflow drains having the same size as the roof drains shall be installed with the inlet flow line located 5 centimeters (2 inches) above the low point of the roof, or overflow scuppers having three times the size of the roof drains may be installed in adjacent parapet walls with the inlet flow line 5 centimeters (2 inches) above the low the point of the adjacent roof and having minimum opening height of 10 centimeters (4 inches). Overflow drains shall be connected to drain lines independent from the roof drains.

   3. Concealed Piping. Roof drainage overflow drains, when concealed within the construction of the building, shall be installed.

   4. Over Public Property. Roof drainage water from a building shall not be permitted to flow over public property, except for Groups A and J Occupancies.

5. Flashing. At the juncture of the roof and vertical surface, flashing and counterflashing shall be provided.