ADVANCED BUILDING MEASUREMENTS

MEASUREMENT OF REINFORCED CONCRETE WORKS

Categories

Reinforced concrete is concrete reinforced with steel bars or fabrics to provide much greater

resistance to tensile stresses. It is necessary to distinguish between in situ concrete, where the

concrete is poured in its final position on the site, and precast concrete where the components

are prefabricated and subsequently placed in position in the structure. Another type is pre-

stressed concrete, where a stress is artificially introduced in the concrete by means of tendons

tensioned before working loads are applied.

Measurement of Reinforced Concrete

The concrete work in the BOQ should start with a general description of the work, where it is

not evident from the location drawings.

The normal procedure in measuring a reinforced concrete structure is to work on a floor by

floor basis, proceeding from the lowest floor upwards, and making the necessary adjustments

on walls, columns, and floor roof slabs for formwork to beams.

Reinforced concrete work consists of three component parts concrete, reinforcement and

formwork.

The bulk of in situ concrete work is measured by volume, stating the thickness range for

beds, slabs and walls.

Isolated columns are classified as columns or walls, according to the ratio of length to

thickness; to be measured as an isolated column, the length on plan is four times the

thickness (SMM E10.M4).

In situ Concrete All concrete must be adequately described by kind and quality of

materials and mix or strength (SMM E10.S1). Reinforced work shall be so described and,

where the volume of reinforcement > 5 per cent of that of the concrete, this shall be stated

because of the difficulties of placing and compacting concrete in heavily reinforced members.

(The Code of Procedure emphasizes that this high reinforcement content will only apply in

exceptional cases, as it will have to exceed 0.41 t/m3 of the measured member).

Unless concrete in foundation, ground beams and the like is poured on or against earth or

unblended hardcore and so described, formwork must be support the concrete.

An extensive list of concrete categories is incorporated in SMM.E10.1 14, where a

considerable number of groupings occur. For example, concrete to foundations is deemed to

include attached column bases and pile caps (SMM.E10.D1). Slabs and their supporting

beams are measured in m3, stating the thickness of the slab in

the appropriate thickness range as SMM.E10.5.1 3. The

thickness range is not varied for the attached beams and

beam casing which are included in with the volume of the

slab, provided their depth is three times their width (depth

measured below the slab). Similar approaches are applied to

beds, blinding beds, plinths, and their thickenings (SMM.E10.D3), and walls with attached

columns and piers (SMM.E10.D6).

When measuring treating the surface on concrete, each type such as power floating and

trowelling is kept separate, distinguishing between

finishing sloping, to falls, cross falls and soffits and

measured in m2 (SMM.E41.1 7.0.0). (Leaving the top

surface of concrete foundations to receive brickwork does

not fall in to this category).

Reinforcement The two main types of reinforcement are measured differently. Bars are

measured by length at taking off stage and subsequently billed in tones to two places of

decimals (SMM.E30.1 and General Rules 3.3). Fabric reinforcement is measured in m2.

Strips in wall foundations and tension strips to floors and roofs are separately described

stating the width of strip (SMM.E30.4.1.0.2).

Each diameter (nominal size) of bar is given separately, as also are straight, bent and curved

bars (SMM.E30.1.1.1 3), and the billed item is deemed to include hooks and tying wire, and

spacers and chairs which are at the discretion of the contractor, without the need for specific

mention (SMM.E30.C1).

Reinforcement is not classified as to location. The description of the bars shall state the kind

and quality of materials (SMM.E30.S1). Since it is difficult to handle and fix long bars,

horizontal bars and bars sloping 300 from the horizontal, 12.00 m long and over are so

described, stating the length in further stages of 3.00 m, while with vertical bars and those

sloping > 300 from the horizontal, the separate 3.00 m stages start with lengths of 6.00 m and

over. Bent bars cover those which are specifically bent to curves to suit the shape of the

member in which they are to be placed (Code of Procedure E10.1.1.3).

The length, number and shape of each bar type is generally given in reinforcement or bar

bending schedule, from which the details are extracted at the taking off stage.

It will be necessary to make adjustments for concrete cover to the reinforcement to prevent

rusting usually taken at about 40 mm and additions for hooked ends (often calculated at

twelve times the diameter of the bar) and turned ends (usually around 75 mm).

Length of each of the bars are then systematically entered in the dimension column, taking

care to ensure that each type of bar is listed and that the correct timesing figures are inserted.

The description of fabric reinforcement includes the kind and quality of steel (SMM.E30.S1).

it is measured in m2 as the area covered with no allowance for laps and no deductions for

voids 1.00 m2 (SMM.E30.M4 and 5). The description of the fabric shall state the mesh

reference, weight per m2 and minimum laps (SMM.E30.4.1.0.0 and E30.S6). (The estimator

has to allow for the laps when calculating his fabric rate / m2). Fabric reinforcement is

deemed to include laps, tying wire, all cutting and bending and spacers and chairs which are

at the discretion of the contractor (SMM.E30.C2).

Form Work Formwork is grouped in one of the categories listed in SMM.E20.1 26. No

deductions are made for voids in formwork to soffits of slabs or wall 5.00 m2, irrespective

of location (SMM.E20.M4 and 8). Certain categories of formwork are kept separate and

suitably described left in, permanent, and to curved surfaces stating the radii

(SMM.E20.M2). Formwork to soffits of slabs and landings is classified according to the

thickness of the concrete and the soffit height as 1.50 m high and thereafter in 1.50 m

stages. Formwork to walls at a height > 3.00 m above floor level is kept separate and so

described and that to vertical and battered surfaces is separately classified.

Formwork to sides of foundations and ground beams, edges of beds and slabs and associated

items is measured in m2 where > 1.00 high. It is measured as linear items where 1.00 m

high, in three categories - 250 mm, 250 500 mm and 500 mm 1.00 m high, and

described as plain vertical or giving a dimensioned description (SMM.E20.1 7.1 2.1 4.1

2).

Formed finishes to concrete are measured in m2 as extra over basic finish, being the finish

formed from the principal formwork (SMM.E20.20.1 5.0.0 and E20.D11 and Code of

Procedure).

Formwork is deemed to include all cutting, splayed edges and the like, and adaptation to

accommodate projecting pipes, reinforcing bars and the like (SMM.E20.C1 and 2).

Formwork to soffits of slabs and landings 200 mm thick are given separately, and thereafter

in 100 mm stages, stating the number of soffits to landings, and whether horizontal, sloping

150, or > 150, height to soffit 1.50 m and thereafter in 1.50 m stages and whether left in or

permanent (SMM.E20.8 9.1 2.1 3.1 4). Formwork also measured to top surfaces

sloping > 150 (SMM.E20.11 and E20.M7).

Formwork to beams, beam casings, columns and column casings are classified as either

attached to slabs, attached to walls or isolated, and measured in m2 when of regular shape,

stating the shape. When of irregular shape, it is measured in meters, supported by a

dimensioned diagram. In both cases it is necessary to state the number of members in each

item. Regular shaped members include rectangular, circular, hexagonal or other definable

regular shapes (SMM.E20.D10). The same height to soffit classifications apply as previously

described (SMM.E20.13 16.1 3.1 2.1 2). Descriptions of formwork to edge beams

shall include the attached edge of slab (SMM.E20.M12), while formwork to recesses, nibs

and rebates is measured in meters, stating the number and giving a dimensioned description,

and described as extra over the formwork in which they occur on superficial items of

formwork (SMM.E20.17 19.1.0 and E20.M14).

Formwork to wall kickers is measured in

meters along the center line of the wall and is

deemed to include both sides

(SMM.E20.21.0.0.0 and E20.M15). suspended

wall kickers (SMM.E20.22) constitute a

separate item and occur where a concrete wall

rises off a concrete slab, the kicker being cast integrally with the slab and hence, at the time

the kicker formwork is erected, there is nothing to support its bottom edge (Code of

Procedure: SMM.E20.21 22).

Sequence of measurement of reinforced concrete floors and roofs

1. In situ concrete to slabs, beams and beam casings in m3 (SMM.E10.5, 9 & 10).

2. In situ concrete to upstands, deep beams and deep beam casings, if any, in m3,

separately classified (SMM.E10.9 - 10.2 3.0.1 and E10.14.0.0.1).

3. Formwork to soffit of slabs and landings in m2 giving the appropriate slab thickness

range and plane (SMM.E20.8 9.1 2.1.1 2).

4. Formwork to beams and beam casings in m2 where of regular shape, stating the

number of members (SMM.E20.13 14.1 3.1.1 2).

5. Formwork to sides of upstands in meters where 1.00 m high and classified as plain

vertical or giving a dimensioned description (SMM.E20.4.1 2.2 4.0).

6. Adjust formwork in slabs where beam occur if not adjusted previously.

7. Formwork to edges of suspended in meters, if 1.00 m high, in prescribed height

categories, classified as for sides of upstands (SMM.E20.3.1 2.2 4.0).

8. Reinforcement in slabs and beams (bars in kg subsequently reduced to tones, keeping

each diameter (nominal size) separate, and fabric in m2).

9. Adjustment if required on supporting brickworks for concrete slabs and beams.

Measurement of reinforced concrete staircase

The in situ concrete in the steps, waist, string beams and base blocks are all grouped together

in reinforced in situ concrete, stating the mix or strength, in staircase (SMM.E10.13). This is

followed by the formwork measured in meters to the

stairflights, stating the number and widths of

stairflights and describing the waists, risers and giving

the width of strings (SMM.E20.25.1.1.0).

Alternatively, dimensioned diagrams may be used.

Formwork to stairflights is deemed to include soffits, risers and strings

(SMM.E20.C5). Formwork items are however required to spandril ends

and the base block, and dimensioned diagrams have been incorporated to

help the estimator. Formwork to soffits of landings is dealt with in the same

way as soffits of slabs (SMM.E20.9.1 2.1 3.1 - 2).

The concrete and formwork items are followed by the steel reinforcement

measured linearly in the first instance, to be subsequently

converted to weight. Straight, bent and curved bars are

distinguished from those in links, which include stirrups

and binders, and each diameter (nominal size) of bar is

kept separate (SMM.E30.1.1.1 4.0).

The remaining items in the staircase are then taken, including the surface treatment of

concrete, where appropriate, granolithic paving to treads and risers and associated work. The

metal balustrading is measured under an appropriate headings in meters with a dimensioned

or component drawing (SMM.L31.2), followed by extra over enumerated items for

ornamental ends and the like to handrails.