Last updated on September 7th, 2023 at 11:45 pm
Precautions while designing and constructing Fire place and Chimneys
Fire places and chimneys should be properly designed and constructed according to certain building bye-laws to avoid any trouble afterwards.
Thus following principles and precautions should be observed while designing constructing fire places chimneys:
1) The depth of foundation of chimney or a fire-place should be same as that of the adjacent wall,
2) The size of the fire place opening should be according to the requirement. Its size should be 500mm wide and 600mm high for a small bed room but its medium size is 1m wide and 1.2m high for a modern kitchen.
3) The head or top of a fire-place opening should be finished with either a concrete lintel or an arch.
4) The chimney jambs of the fire place should not be less than 200mm wide.
5) Each fire place should have a separate flue and the portion between the separate flues should be air tight.
6) The minimum size of each flue should be 200mm X 200mm.
7) The flue should be constructed uniform in shape and size throughout their height.
8) Each bend in a flue should be properly rounded off and then inclination should always be less than 45° to the horizontal.
9) The Inner surface of the flue should be rendered smooth with rich cement mortar (1:3) mixed with 1 part cowding. This is known as parging or pargeting.
10) All the flues different fire places in a building should be gathered and grouped in one stack, if possible.
11) There should be no wood work built in the wall within 300mm of flue or fire-place opening
12) There should be no metal fastening built in the wall within 0.2m (800mm) of a flue or fire place opening.
13) The hearth of the fire place should be constructed from incombustible material which should not be less than 150mm thickness.
14) All the walls of a chimney stack should be built in rich water-proof cement mortar starting from its lowest junction with the roof.
List the different factors affecting thickness of walls in brick masonry
Following are the factors affecting thickness of walls in brick masonry:
a) The total load to be carried by the wall: The total load to be carried by a wall induces dead load, live load and wind load. The total vertical load may be concentric or eccentric. The quantity of total load and its nature affect the thickness of the wall because more is the quantity or eccentricity of the total load, greater is the thickness of the wall required.
b) Overall height of the wall: The distance between the top of foundation concrete and the highest part of the wall is known as the overall height. The height of the parapet wall up to 1 metre is neglected and the height of wall with gable end is measured upto centre of the triangular portion of the wall. Thus more the overall height of the wall of a building, more will be the desired thickness of walls
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c) Height between floors: The height between floors is fairly constant for domestic buildings, ranging from 2.8 to 3.2 metres, while it varies considerably in case of public buildings such as halls, temples, etc. Thus the height between floors also plays an important role in the design of thickness of walls as floors give lateral support to the walls. The more the height between floors, more will be the desired thickness of wall.
d) Length of the wall: The length of wall between the centres of supports in the form of piers, buttresses etc. provided to give lateral support to the wall at regular horizontal intervals also affects the thickness of walls. The more the length of wall, more will be the thickness
e) Strength of materials: The crushing strength of bricks and the mortar to be used in the construction of a wall should also be considered while deciding the thickness of the wall.
More the strength of these materials to be used in the construction less will be the desired thickness of the wall.
The thickness of a wall is decided after thorough study of all above factors in such a way that the maximum slenderness ratio is obtained.
Since the thickness of a wall depends upon these variable factors, therefore local authorities such as municipal committees, trusts, corporations have prepared their own Bye-laws regarding the thickness of walls to suit the conditions of their respective localities.
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