Building Construction & Maintenance Engineering (General Engineering) (SSC JE)

The main purpose of providing foundation to a building is to distribute the weight of the structure on a sufficiently large area of the sub stratum.

English bond–Alternate courses of header and stretcher.
• English bond is stronger and costly than flemish bond.
• Mostly English bond is used in government work.
• Adopted for work where strength is prime important
Flemish bond–Each cause has alternate header and stretcher.
• Flemish bond give better appearance than English bond.
• Construction with flemish bond requires greater skill in comparison to English bond and bat bricks are use in it.

The nominal thickness of an expansion joint in brick walls, is kept more than 20 mm.
Standard thickness = 15 mm
Nominal thickness = 20 mm

Shoring–
• Temporary supports used to support unsafe building (or used to support buildings while they are repaired) are called shores.
• They are classified into three classes according to their positions in space as follows–
1. Raking or inclined shores
2. Horizontal or flying shores
3. Vertical or dead shores
Flying shores or Horizontal shores–These shores are used to support two parallel walls which are in danger due to the removal of an intermediate building.
• There are two types of flying shores
(i) Single flying shores
(ii) Double flying shores
• Single shores are used if the distance between the walls is upto 9 m. For larger distances between the walls.

Dead shores–The following types of objectives of dead shores–
(i) To rebuild the lower part of a defective load bearing wall.
(ii) To rebuild the existing foundations, which have either become unsafe or require strengthening for carrying heavier loads.

According to IS : 875 (Part-2)–
• Live load for individual rooms like kitchen, bathrooms, bedroom is taken as 2 kN/m².
• Live load for balconies and corridors taken as 3 kN/m².
Hence, the minimum live load to be consider for residential building is 2 kN/m² that is 2000 N/m².

Plastering is most usually done using a cement mortar mix of 1 : 4 or 1 : 6, with a richer mix (1 : 4) used for exterior wall.
• The recommended ratio for mixing hydraulic lime and sand is 1 : 2.

Gauged cement mortar–Mortar is produced by mixing a binding material (cement and lime) with fine aggregate (sand, surkhi etc.) with water.
• Types of mortar are follows–