RBSE SS Voc Construction key terms

The maximum load per unit area that the ground beneath a foundation can carry without failing or settling excessively. It decides the size and type of footing needed for a structure.

The increase in the volume of moist sand caused by films of water pushing the grains apart. It is why sand is measured dry when batching concrete so mix proportions stay correct.

A field test in which freshly mixed concrete is placed in a standard cone, the cone is lifted, and the drop in height is measured. It indicates workability, not strength.

How easily fresh concrete can be mixed, placed, compacted and finished without segregation. It depends on water content, aggregate shape and grading, and the use of admixtures.

The stated proportions of cement, fine aggregate and coarse aggregate, often with a water-cement ratio, used to batch a concrete grade. For example 1:2:4 denotes cement to sand to coarse aggregate.

The mass of water divided by the mass of cement in a concrete mix. A low ratio raises strength and durability, but too little water makes the mix unworkable.

Keeping freshly placed concrete moist and at a suitable temperature for a set period so cement hydration continues. Proper curing develops strength, reduces shrinkage cracks and improves surface durability.

Removing trapped air from freshly placed concrete, soil or asphalt by vibration, tamping or rolling. Good compaction increases density, strength and impermeability and prevents honeycombing.

A paste of cement or lime, sand and water used to bind masonry units and to plaster surfaces. It sets hard and also accommodates small irregularities between bricks or blocks.

The planned overlapping arrangement of bricks or blocks so that vertical joints do not line up in successive courses. Bonds such as stretcher and English spread load and strengthen the wall.

A single horizontal layer of bricks, blocks or stone in a wall. Courses are kept level and of even thickness so the wall rises truly and loads pass down uniformly.

Exactly vertical, as checked with a spirit level or plumb bob. Walls, columns and door frames must be plumb so they stand straight and carry load as designed.

Exactly horizontal, or the instrument reading that establishes a horizontal line or plane. Levels are transferred across a site using a dumpy level, automatic level or water level.

A fixed reference point of known reduced level, often a brass plate or marked peg, from which other levels on a site are derived. It anchors all setting out and earthwork heights.

The height of a point expressed relative to a chosen datum, usually mean sea level. Surveyors compute it from backsight and foresight readings in a level book.

The first staff reading taken on a point of known level after setting up the instrument. It establishes the height of the instrument line and is used to compute reduced levels.

Marking on the ground the exact position, size and alignment of a building or structure from the drawings. Pegs, profiles and string lines transfer dimensions before excavation begins.

A numbered or lettered reference line on a drawing that locates columns, walls and other elements. On site, grid lines are set out with pegs so positions match the design.

The ratio between a drawn length and the real length it represents, such as 1:100. Choosing the right scale lets a drawing show a whole building on a manageable sheet.

A detailed, dimensioned drawing that gives the builder all information needed to construct an element, including sizes, materials and levels. It is issued for construction, not for approval.

An itemised schedule listing measured quantities of work with descriptions, prepared from drawings so tenders can be priced on the same basis. It forms part of the contract documents.

The process of measuring quantities of work item by item from drawings and schedules. Accurate take-off feeds the bill of quantities and the estimate of cost.

Working out the unit cost of a construction item from materials, labour, plant, overheads and profit. It justifies the rate entered against each item in an estimate or tender.

A sum set aside in an estimate to cover unforeseen work, price rises or site conditions. It is usually a percentage of the estimated cost and is spent only with approval.

The lower part of a structure that transfers loads safely into the ground. Shallow footings suit strong soil; deep piles or rafts are used where soil is weak or loads are heavy.

A continuous impervious layer built into a wall near ground level to stop moisture rising by capillary action. It is commonly a polythene sheet or bituminous felt.

Applying one or more coats of mortar to a wall or ceiling to give a smooth, protective finish. Correct thickness and curing prevent shrinkage cracks and hollow patches.

A powered tool with a flexible needle or a beam that shakes fresh concrete to expel air. Used correctly it removes voids; overuse causes segregation of the mix.

An optical instrument for measuring horizontal and vertical angles precisely. It is used for setting out angles, extending grid lines and checking alignment of structures.

An electronic instrument combining angle measurement with distance measurement and onboard computing. It records coordinates directly, speeding up setting out and topographic survey work.

Gear worn by a worker to reduce injury risk, such as helmet, boots, gloves, goggles and high-visibility vest. It is the last line of defence after hazards are controlled at source.

A short briefing held on site before work starts to explain the day's tasks, hazards and controls. It records attendance and keeps safety communication regular and practical.

A written document describing the safe sequence, plant and controls for a construction activity. It is agreed before work begins and is used alongside risk assessments.

A temporary working platform of tubes, boards and couplers giving access at height. It must be erected by competent persons, tied to the structure and inspected at stated intervals.

Separation of the constituents of a mix, such as coarse aggregate settling away from mortar during over-vibration or long pours. It weakens the hardened concrete and spoils the finish.

Spotting a construction-related opportunity and organising money, people and materials to serve it at a profit. It involves risk-taking, pricing, marketing and managing cash flow.

The personal and workplace abilities that make a candidate useful to an employer, such as punctuality, teamwork, safe working, problem solving and willingness to learn. They are assessed alongside technical skill.

Giving full attention to a speaker, checking understanding and responding appropriately. On site it prevents errors when receiving instructions, dimensions or safety briefings.

A precise, standardised drawing using lines, symbols and dimensions to convey construction information. It follows conventions of projection, line type and lettering so anyone trained can read it.