How to estimate quantities for construction jobs

There are three basic methods of estimation that contractors use to predict various quantities for construction jobs. These can include how much soil to excavate, how much concrete to mix, how many bricks to order and what additional building materials need to be used. 

These methods of estimation allow contractors to place orders and work out their budgets before the building actually starts. The three ways to make estimations include; the long wall/short wall method, the centreline method and partly cross wall method. They are outlined below.

Long wall/short wall method of estimation

In this process, a room is said to have two long walls and two short walls. The long wall is the one with a greater length, while the short wall is the one perpendicular (90°) to it. The length must be taken along the wall’s centreline. To measure the length of the long wall, contractors must use the architect’s plans and add half a brick’s breadth at each end of the wall’s centreline.

Once this is known, the length of the short wall can be calculated by deducting half a brick’s breadth from its centreline at each end. These lengths are then multiplied by the breadth and length of the bricks to be used in order to get an estimation of how many bricks to order.

Centreline method of estimation

This process is suitable for walls of similar cross-sectional areas or square rooms. Here, the total centreline length is multiplied by the length and width of the bricks to get an estimation of the quantity needed. When other walls join the main wall, the centreline length is reduced by half a brick’s breadth at each junction.

Partly cross wall way to estimate

This method is used when a building’s external wall is a different thickness to its internal wall. In these cases, the centreline method is used for the external walls and the long wall/short wall method is used for the internal walls – hence the name ‘partly cross wall’ method. This is a commonly used process in construction projects as buildings often use single-brick walls on the interior and double-brick walls on the exterior.

These methods of estimation are fairly accurate and can be used to judge how much soil to remove for the foundations, as well as how many bricks and bags of cement need to be ordered. They allow contractors to plan ahead and get prepared for a construction project before breaking ground.


Release your inner creative-being and get stuck into some trendy DIY projects. We share ways to add personal flair to your life with some homemade décor and unique craft ideas. 


Follow us on Facebook, Instagram and Pinterest for more articles, videos and content to keep you inspired. 


Mobimeme offers content marketing, SEO, analytics, social media management and expert direction in the digital sphere. Building and growing online audiences for your business is what we do best. Get in touch with us to find out more about our package offerings and how you can improve your website and following.

What do you think?

101 points
Upvote Downvote

Written by Editor

The importance of proper safety for construction projects

The importance of proper safety for construction projects

One-third of food waste occurs before it is sold

One-third of food waste occurs before it is sold