Brickwork and Blockwork

Introduction 

Bricks can be obtained in a number of sizes and various compositions, strengths and shapes, to mention only the more obvious factors. The appropriate British Standards give details for clay, concrete, sand-lime and other bricks. 

To give examples of rates using all of the different types of bricks would be impossible in the space allocated, as well as highly repetitive. Therefore the examples in this chapter will concentrate on a metric brick with dimensions 215 mm long, 102.5 mm wide and 65 mm thick. Whether the brick is solid, hollow or perforated, or has single or double frogs, will make no difference to us here, although in theory the different weights of bricks could affect the laying output per man and other factors.

Mortar 

If bricks have no perforations or frogs, are absolutely rectilinear, are laid on a bed of mortar 10 mm thick and have each end jointed 10 mm thick, then 1000 bricks require the following volume of mortar: 

1000[(0.215 x 0.1025 x 0.01) + (0.1025 x 0.065 x 0.01)] = 0.287 m3 

The amount of mortar taken by estimators varies from 0.5 to 0.8 m3. This makes allowance for the mortar which disappears into the frogs, hollows or perforations in the bricks, and also for the large amount of waste generated. This waste occurs throughout the process: cement, lime and sand are dumped on the ground and trodden in; mortar is left in the drum of the mixer, in the barrow, on the mortar board and on the scaffold; and mortar is squeezed out of the bed and joint of every brick. The allowance is large, but there is a lot of waste. The mixes and costs of mortars used in the examples in this chapter are given in Appendix A at the end of the book. 

Bricks per wall area Obviously we need to know the number of bricks to be laid in each square metre of wall. For a half brick wall laid using metric bricks with dimensions 215 x 102.5 x 65 mm and mortar joints of 10 mm, the number of bricks required per square metre is given by: 

               1000 x 1000 = 59.25925, say 59 

                    225 x 75 

One brick walls need 118 bricks:, one and a half brick walls need 177 bricks; and so on. The waste on bricks can vary as with any other material, but in this chapter we will allow a modest 5 per cent. 

Labour costs 

Labour costs depend first on the squad make-up, i.e. the numbers of craftsmen and labourers. In the examples in this chapter, the squad comprises two bricklayers and one labourer. 

The second factor is the number of bricks which each bricklayer can lay per hour. Fanciful claims arc common on building sites; tales abound of bonuses earned, records shattered and employers dumbfounded. The truth is much less in magnitude. A good average - every day, 5 days a week, 47 weeks per annum - is 55-65 common bricks per hour. Obviously this is in straight runs of walling without excessive cutting for bond and without anything unusual. Output might be a little higher on thicker walls simply because the bricklayers and their labourer are spending proportionately less time moving along the wall.