Measurement of Masonry Brick Works in Construction
In the realm of construction, accurate measurement of masonry brick works is crucial for estimating material quantities and evaluating completed tasks.
Masonry works involve the use of cement and fine aggregates without coarse aggregates, and they encompass various types, such as brick masonry, concrete block/brick masonry, stone/rubble masonry, and clay tiles. To ensure precise calculations and cost estimations, it is essential to understand the measurement process and the deductions involved.
Types of Masonry Works:
Before delving into the measurement techniques, it’s important to familiarize oneself with the different types of masonry works commonly encountered in construction:
- Brick Masonry
- Concrete Block/Brick Masonry
- Stone/Rubble Masonry
- Clay Tiles, etc.
Measurement of Masonry Works:
Masonry works, including brick masonry, concrete block, stone or rubble masonry, are typically measured in terms of volume. However, when the masonry thickness is limited to a single brick or block, area measurement is employed. Tiling works are measured solely in terms of area. It is worth noting that the measurement process does not account for material wastage, such as bricks, cement, or sand. Moreover, the specific types and classes of bricks, blocks, or tiles are not considered during quantity measurements. These aspects are factored in during pricing calculations, which take into account various masonry work categories to determine the precise construction cost.
Rules for Measurement of Masonry Works:
To ensure consistency and accuracy in measuring masonry works, the following general rules are commonly followed:
- Masonry is measured as “net in place,” with deductions made for openings like doors, windows, and ventilation.
- Different shapes of masonry units, such as rectangular or circular, are measured separately.
- Masonry at different heights is measured individually, considering that higher elevations may require scaffolding and hoisting.
- Masonry work is categorized and measured separately, including facings, backing to facings, walls and partitions, furring to walls, and fire protection.
- Surface cleaning requirements are measured in terms of area (square meter or square feet).
- Special treatments applied to masonry surfaces, such as coatings or finishes, are measured in area, with the number of coats applied recorded.
- Joints in masonry structures, such as expansion joints or control joints, are measured in length (meter or feet), specifying the joint type and filler material used.
- Different types of mortar or mortar with various admixtures are measured separately in volume (cubic meter or cubic feet).
- If reinforcement is used in masonry, it is measured separately.
- Additional items incorporated into masonry, including anchor bolts, sleeves, and brackets, are described and measured individually.
- The presence of weep holes is enumerated, especially when plastic inserts or similar materials are required.
- Rigid insulation added to masonry work is measured in square feet or square meters, noting the material type and thickness.
Measurement of Brick Masonry:
Brick masonry follows the general measurement rules mentioned earlier, with additional considerations specific to this type of construction:
- Brick masonry is measured in volume when the thickness exceeds that of a single brick. For single-brick masonry, measurement is done in square meters.
- Facing bricks are measured separately to account for their distinctive characteristics.
- Different types or classes of brick masonry are measured individually to ensure accurate cost estimation.
Measurement of Concrete Block Masonry:
Measurement of concrete block masonry also aligns with the general rules, incorporating the following specific considerations:
- Different types of concrete block masonry, including variations in block size and type, are measured separately.
- Special units required at corners, jambs, heads, sills, and similar locations are measured individually.
- Measurement of concrete core fills and bond beams involves specifying the strength and type of concrete used, measured in cubic feet or cubic meters. This measurement is conducted separately for different types of concrete blocks based on their strength.
- Linear measurement (feet or meters) is used for reinforcing steel in core fills and bond beams, indicating the size and type of rebar employed.
Deductions for Openings and Bearings in Masonry Works Measurements:
In masonry works, certain deductions are made for openings and bearings, while others are not accounted for. Deductions are not made for openings up to 1000 square centimeters (0.1 square meter), ends of beams, posts, rafters, etc., up to 500 square centimeters (0.05 square meter) in section, and bed plates, wall plates, and balcony (chajja) bearings up to 10 centimeters in depth. Deductions for other openings are determined as follows:
Deductions for Rectangular Openings:
For rectangular openings in masonry walls, full deductions are made by multiplying the length (L) by the height (H) and the thickness of the wall.
Deductions for Reinforced Concrete and Reinforced Brickwork:
When dealing with reinforced concrete and reinforced brickwork, measurements are taken in cubic meters for components such as roof or floor slabs, beams, lintels, columns, and foundations. The length, breadth, and thickness are accurately derived from plans, elevations, sections, or detailed drawings. The quantities are computed in cubic meters, excluding steel reinforcement, bending, and inclusive of centering, shuttering, fixing, and binding the reinforcement in position. The weight of reinforcement, including bending, is considered separately under steelwork. In cases where specific details are unavailable, a standard percentage (0.6% to 1%, typically 1%) of the volume of reinforced concrete or reinforced brickwork is allocated for steel. The volume of steel does not need to be deducted from the overall volume of reinforced concrete or reinforced brickwork. Alternatively, reinforced concrete and reinforced brickwork can be estimated inclusively, accounting for steel, centering, shuttering, and the complete work. Centering and shuttering are often included in the measurement of reinforced concrete or reinforced brickwork, but they can also be treated as a separate item per square meter of surface area in contact with concrete.
Deductions for Flooring and Roofing Works:
The concrete base and the finishing layer, be it cement concrete, stone, marble, mosaic, etc., are usually considered as a single job or item. The quantity is calculated in square meters by multiplying the length by the breadth, measured as the inside dimensions from wall to wall of the superstructure. Both the base concrete and the floor finishing are treated as one item for payment purposes.
The supporting structure is measured separately in cubic meters, while the lime concrete terracing is computed in square meters with a specified thickness as a separate item. This includes surface rendering to achieve a smooth finish. The compacted thickness of lime concrete terracing typically ranges from 7.5 cm to 12 cm on average. Alternatively, lime concrete terracing can be calculated in cubic meters using the average thickness.
Plastering, usually 12mm thick, is measured in square meters. The measurement accounts for the entire face of the wall, treating both sides as solid. Deductions for openings are made in a similar manner to plastering deductions.
Pointing in the wall is calculated in square meters, and deductions are made following a similar approach as plastering deductions. Cornice, Pillars, Woodworks, Ironworks, and White Wash or Color Washing: Ornamental cornice and large cornice are measured in running meters or running feet for the complete work, encompassing masonry, plastering, moldings, etc., and are paid accordingly. String courses, corbelling, coping, and other similar elements are also measured and paid for in running meters for the complete work. Pillars are measured separately in cubic meters, considering their net volume. Woodworks, including beams, posts, roof trusses, and doorposts, are computed in cubic meters based on the finished dimensions. Ironworks are measured by weight in kilograms or quintals, accurately calculated by multiplying the weight per running meter by the length. The weight per running meter can be obtained from the steel section book. For steel joints, the length is determined by the clear span plus two bearings, which may be a fraction of the wall thickness or 20 to 30 centimeters. White wash, color washing, or distempering are measured in square meters and typically follow the same measurements as plastering. Internal white wash or distempering is often considered the same as outside plastering and inside plastering, and separate calculations are unnecessary.
Accurate measurement of masonry brick works is vital in construction for estimating material quantities and determining project costs. The measurement process involves following general rules and considering specific guidelines for each type of masonry work.
Deductions are made for openings, while various elements such as reinforced concrete, flooring, roofing, plastering, and ornamental features require separate considerations. By adhering to these measurement guidelines and deductions, construction professionals can ensure precise calculations, efficient resource management, and accurate cost estimations for masonry brick works.