National Building Code of the Philippines

(2.5) Masonry Chimneys for Incinerators Installed in Multi-Storey Buildings (Apartment-Type Incinerators) Chimneys for incinerators installed in multi-storey building using the chimney passageway as a refuse chute where the horizontal grate area of combustion chamber does not exceed 0.80 square meter shall have walls of solid masonry or reinforced concrete, not less than 100 millimeters thick with a chimney lining as specified in this Code. If the grate area of such an incinerator exceeds 0.80 square meter, the walls shall not be less than 100 millimeters of firebrick except that higher than 9.00 meters above the roof of the combustion chamber, common brick alone 200 millimeters in thickness, may be used. (2.6) Masonry Chimneys for Commercial and Industrial Type Incinerators Masonry chimneys for commercial and industrial type incinerators of a size designed for not more than 110 kilograms of refuse per hour and having a horizontal grate area not exceeding 0.50 square meter shall have walls of solid masonry or reinforced concrete not less than 100 millimeters thick with lining of not less than 100 millimeters of firebrick, which lining shall extend for not less than 12.00 meters above the roof of the combustion chamber. If the design capacity of grate area of such an incinerator exceeds 110 kilograms per hour and 0.80 square meter respectively, walls shall not be less than 200 millimeters thick, lined with not less than 100 millimeters of firebrick extending the full height of the chimney. (3) Linings Fire clay chimney lining shall not be less than 15 millimeters thick. The lining shall extend from 200 millimeters below the lowest inlet, or, in the case of fireplace, from the throat of the fireplace to a point above enclosing masonry walls. Fire clay chimney linings shall be installed ahead of the construction of the chimney as it is carried up, carefully bedded one on the other in fire clay mortar, with close-fitting joints left smooth on the inside. Firebrick not less than 500 millimeters thick may be used in place of fire clay chimney. (4) Area No chimney passageway shall be smaller in area than the vent connection of the appliance attached thereto. (5) Height Every masonry chimney shall extend at least 600 millimeters above the part of the roof through which it passes and at least 600 millimeters above the highest elevation of any part of a building within 3.00 meters to the chimney. (6) Corbeling No masonry chimney shall be corbeled from a wall more than 150 millimeters nor shall a masonry chimney be corbeled from a wall which is less than 300 millimeters in thickness unless it projects equally on each side of the wall. In the second storey of a two-storey building of Group A Occupancy, corbeling of masonry chimneys on the exterior of the enclosing walls may equal the wall thickness. In every case the corbeling shall not exceed 25 millimeters protection for each course of brick. (7) Change in Size or Shape No change in the size or shape of a masonry chimney shall be made within a distance of 150 millimeters above or below the roof joints or rafters where the chimney passes through the roof. (8) Separation When more than one passageway is contained in the same chimney, masonry separation at least 100 millimeters thick bonded into the masonry wall of the chimney shall be provided to separate passageways. (9) Inlets Every inlet to any masonry chimney shall enter the side thereof and shall be of not less than 3 millimeters thick metal or 16 millimeters refractory material. (10) Clearance Combustible materials shall not be placed within 50 millimeters of smoke chamber or masonry chimney walls when built within a structure, or within 25 millimeters when the chimney is built entirely outside the structure. (11) Termination All incinerator chimneys shall terminate in a substantially constructed spark arrester having a mesh not exceeding 20 millimeters. (12) Cleanouts Cleanout openings shall be provided at the base of every masonry chimney. (b) Fireplaces and Barbecues Fireplaces, barbecues, smoke chambers and fireplace Chimneys shall be of solid masonry or reinforced concrete and shall conform to the minimum requirements specified in this Code. (1) Fireplace Walls. Walls of fireplaces shall not be less than 200 millimeters in thickness. Walls of fireboxes shall not be less than 250 millimeters in thickness: Except, that where a lining of firebrick is used, such walls shall not be less than 200 millimeters in thickness. The firebox shall not be less than 200 millimeters in thickness. The firebox shall not be less than 500 millimeters in depth. The maximum thickness of joints in firebrick shall be 10 millimeters. (2) Hoods . Metal hoods used as part of a fireplace or barbecue shall not be less than No. 18 gauge copper, galvanized iron, or other equivalent corrosion-resistant ferrous metal with all seams and connections of smokeproof unsoldered construction. The goods shall be sloped at an angle of 45 degrees or less from the vertical and shall extend horizontally at least 150 millimeters beyond the limits of the firebox. Metal hoods shall be kept a minimum from combustible materials. (3) Circulators . Approved metal heat circulators may be installed in fireplaces. (4) Smoke Chamber. Front and side walls shall not be less than 200 millimeters in thickness. Smoke chamber back walls shall not be less than 150 millimeters in thickness. (5) Fireplace Chimneys. Walls of chimneys without flue lining shall not be less than 200 millimeters in thickness. Walls of chimneys with flue lining shall not be less than 100 millimeters in thickness and shall be constructed in accordance with the requirements of this Code. (6) Clearance of Combustible Materials. Combustible materials shall not be placed within 50 millimeters of fireplace, smoke chamber, or chimney walls when built entirely within a structure, or within 25 millimeters when the chimney is built entirely outside the structure. Combustible materials shall not be placed within 150 millimeters of the fireplace opening. No such combustible material within 300 millimeters of the fireplace opening shall project more than 3 millimeters for each 25 millimeters clearance from such opening. No part of metal hoods used as part of a fireplace, barbecue or heating stoves shall be less than 400 millimeters from combustible material. This clearance may be reduced to the minimum requirements set forth in this Code. (7) Area of Flues, Throats, and Dampers. The net cross-sectional area of the flue and of the throat between the firebox and the smoke chamber of a fireplace shall not be less than the requirements to be set forth by the Board. Where dampers are used, they shall be of not less than No. 12 gauge metal. When fully opened, damper opening shall be not less than ninety percent of the required flue area. When fully open, damper blades shall not extend beyond the line of the inner face of the flue. (8) Lintel . Masonry over the fireplace opening shall be supported by a non-combustible lintel. (9) Hearth . Every fireplace shall be provided with a brick, concrete, stone, or other approved non- combustible hearth slab at least 300 millimeters wider on each side than the fireplace opening and projecting at least 450 millimeters therefrom. This slab shall not be less than 100 millimeters thick and shall be supported by a non-combustible material or reinforced to carry its own weight and all imposed loads.