(1) Flues. – Every heat-generating appliance producing smoke or other noxious gases shall be provided with a flue complying with the following requirements—

a) no flue shall have smoke-pipe connexions in more than one storey of a building, unless provision is made for effectively closing smoke-pipe openings with devices made of non-combustible materials whenever their use is discontinued temporarily;

b) where a smoke-pipe is permanently in disuse, it shall be completely closed off with concrete, masonry or similar construction;

c) two or more smoke-pipes shall not be joined for a single flue connexion, unless the smoke-pipes and flues are of sufficient size to serve all the appliances thus connected;

d) the cross-sectional area of flues for appliances mentioned in this subsection which burn gas shall be not less than 10 square centimetres per hourly input of 12 megajoules, and in no case shall this cross-section be less than 75 millimetres in diameter;

e) flues shall have cross-sectional areas at least equal to the aggregate areas of the smoke-pipes of the appliances connected to them.

(2) Chimneys; general. – All chimneys erected within or attached to, a building or structure shall be constructed in accordance with the following requirements—

a) chimneys shall be of, and be supported by, non-combustible construction;

b) if chimneys are capped, such capping shall be of brick, terracotta, stone, cast iron, concrete, or other approved non-combustible material;

c) spaces between the chimney and joists, beams or girders, and between the chimney and any combustible materials, shall be fir-stopped by filling with non-combustible material;

d) no change in the size or shape of a flue shall be made within a distance of 150 millimetres of any combustible ceiling or roof-member.

(3) Chimneys for dwelling-houses and industrial low-heat appliances—particular requirements. – Chimneys for dwelling-houses and industrial low-heat appliances shall comply with the following requirements in addition to those specified in subsection (2) –

a) every chimney shall extend at least 600 millimetres above the height point of the roof which is within a radius of 2,25 metres, measured horizontally from the nearest vertical surface of the chimney;

b) chimneys for dwelling-houses shall be constructed of solid masonry-units, reinforced concrete or other approved non-combustible material;

d) n dwelling-houses not exceeding one storey in height, the thickness of the chimney-walls shall be not less than 100 millimetres, if lined as-described in paragraphs (g) to (i), and 215 millimetres if not so lined;

e) in other buildings and in dwelling-houses exceeding one storey in height, the thickness of such walls shall be not less than 215 millimetres;

f) except in the case of chimneys having walls of at least 215 millimetres in thickness, serving dwelling-houses and other buildings appurtenant thereto, every chimney hereafter erected or rebuilt shall be lined with a flue-lining complying with paragraphs (g) to (i);

g) flue-linings shall be made of fire-clay, refractory clay or any other approved refractory material which will withstand the action of material which will withstand the action of flue-gases and resist, without softening or cracking, the temperatures to which they will be subjected, or of cast iron of approved quality, form and construction;

h) flue-linings shall be not less than 12 millimetres in thickness;

i) flue-linings shall start from a point not less than 230 millimetres below the intake, or in the case of fire-places, from the throat of the fire-place and shall extend for the entire height of the chimney;

j) soot-doors and frames for flues or fire-places shall be of cast iron arranged to remain tightly closed when not in use;

k) when two or more flues are contained in the same chimney, each flue shall be separated from the others by masonry or concrete of at least 100 millimetres in thickness bonded into the wall of the chimney;

l) any joimts in the flue-linings of adjacent flues shall be staggered at least 180 millimetres.

(4) Incinerator-chimneys. – Chimneys for incinerators shall comply with the following additional requirements, and shall extend to a height above the roof equal to that required by paragraph (a) of subsection (3) excluding toilet incinerators—

a) Incinerator-chimneys other than fuel-fired incinerators. – Chimneys for incinerators, other than fuel-fired incinerators, erected in buildings of residential, institutional, place of worship, school or college, both residential or non-residential, or restaurant occupancy shall be constructed as follows—

i) when the gate area of the combustion-chamber does not exceed 0,85 square metre and the height of the building does not exceed three storeys, the thickness of the chimney-walls shall be not less than 100 millimetres and the flue shall be lined in accordance with the provisions of paragraphs (g) to (i) of subsection (3);

ii) when the grate area of the combustion-chamber exceeds 0,85 square metre or the building exceeds three storeys in height, the chimney shall be constructed in accordance with the provisions of paragraph (b);

b) fuel-fired incinerator-chimneys. – Chimneys for fuel-fired incinerators shall be lined with refractory-brick lining of at least 114 millimetres in thickness laid in fire-clay mortar and extending to the top of the chimney or to a point not less than 12 metre above the roof of the combustion-chamber, whichever is the lower. The walls of the chimney, including the fire-lining shall be not less than 215 millimetres in thickness.

(5) Chimneys for industrial medium-heat appliances. – Chimneys for industrial medium-heat appliances, other than incinerators, shall comply with the following requirements—

a) every chimney shall extend to a height of not less than 3 metres above the highest point of any roof which is within a radius of 7,5 metres, measured horizontally from the nearest vertical surface of the chimney;

b) if such chimneys are constructed of concrete, the concrete shall be reinforced, and the walls shall be not less than 230 millimetres in thickness and shall, in addition, be lined with not less than 114 millimetres of fire-brick laid in fire-clay mortar, and such lining shall start not less than 600 millimetres below the smoke-pipe entrance, and extend for a height of at least 7,5 metres above the smoke-pipe entrance.

(6) Chimneys for industrial high-heat appliances. – Chimneys for industrial high-heat appliances shall be built to comply with the following requirements—

a) such chimneys shall be built with double walls, each single wall being of not less than 215 millimetres in thickness, with an adequately ventilated air-space of not less than 50 millimetres between them;

b) such space shall be ventilated near the top and the bottom;

c) the inside 114 millimetres thickness of the interior walls shall be of fire-brick laid in fire-clay mortar;

d) such chimneys shall extend at least 6 metres above the highest point of any roof which is within a radius of 15 metres measured horizontally from the nearest vertical surface of the chimney, and shall be covered on the top with heavy wire netting or other approved spark-arrester;

e) no woodwork or other combustible material or construction shall be erected or placed within 1 metre of any part of such chimney.

(7) Fire-place hearths. – Fire-place hearths shall be built in compliance with the following requirements –

a) every fire-place shall have a hearth of brick, stone, tile or other approved non-combustible material supported on a fire-resistant slab or on masonry trimmer-arches;

b) such hearth shall extend at least 450 millimetres outside of the chimney-breast and not less than 30 millimetres beyond each side of the fire-place opening along the chimney-breast;

c) the combined thicknesses of hearth and supporting non-combustible construction shall be not less than 150 millimetres at any one point.

(8) Smoke-stacks. – Every smoke-stack shall comply with the following requirements—

a) every smoke-stack shall be of adequate thickness to withstand all forces, including wind forces, to which it may be subjected, at stresses permitted by these by-laws, and if of metal, shall be properly riveted or welded and, unless structurally self-supporting, shall be securely guyed or firmly anchored to, or otherwise supported by, the building or structure served by such stack;

b) all metal-work shall be painted or galvanized or be of corrosion-resistant alloy;

c) soot-doors shall be provided at the base of every such stack;

d) all metal smoke-stacks used for industrial high-heat appliances shall be lined with 114-millimetre-thick fire-brick laid flat in fire-clay mortar, and such lining shall extend not less than 7,5 metre above the smoke-pipe entrance;

e) smoke-stacks shall extend to a height of not less than the following—

i) for dwelling-houses, industrial low-heat appliances and incinerators, the height set out in paragraph (a) of subsection (3);

ii) for industrial medium-heat appliances, the height set out in subsection (6);

(f) exterior smoke-stacks, or parts of smoke-stacks, erected on the exterior of a building, shall have a clearance from the wall of not less than 115 millimetres. No such stack shall be nearer than 600 millimetres in any direction from a wall-opening, exit-way or fire-escape;

g) interior smoke-stacks, or parts of smoke-stacks, erected within a building other than a one-storey building, shall be enclosed above the storey in which the appliance served by the stack is located, in walls of non-combustible construction having a fire-resistance rating of not less than one hour, with a space on all sides between the stack and the enclosing-walls sufficient to render the entire stack accessible for examination and repair;

h) the enclosing-walls of interior stacks shall be without openings, except doorways equipped with approved self-closing fire-doors provided for inspection purposes;

i) where such stack passes through a roof constructed of combustible material, it shall be protected by a sleeve of non-combustible material extending at least 230 millimetres above and below the roof construction, and providing a clearance all round between stack and sleeve of at least 40 millimetres or one-quarter of the external diameter of the stack, whichever is the greater;

j) such sleeve shall ventilate to the open air above the roof.

(9) Raising adjoining chimneys, smoke-stacks, et cetera. – No person shall, without the consent of the local authority, erect, enlarge or raise a building so that a wall thereof extends above the top of a chimney or smoke-stack attached to an existing building, if such erection, enlargement or raising causes a contravention of the provisions of paragraph (a) of subsection (3) or of subsection (5), or of paragraph (d) of subsection (6), or of paragraph (e) of subsection (8), and such consent may be given on such terms and conditions as the local authority may consider reasonable.

(10) Spark-arresters. – Heavy wire netting or other approved spark-arresting appliances shall be fitted to every chimney, smoke-stack or flue where—

a) the roofing material of the building concerned is of thatch, shingles or other combustible material; or

b) the chimney, smoke-stack or flue serves an incinerator constructed for the burning of any product which may give rise to sparks; or

c) the local authority is of the opinion, on reasonable grounds, that such chimney, smoke-stack or flue is likely to cause the outbreak of fire by the emission of sparks.