Minimise material wastage

When you visit Nicholas Mugabe’s construction site in Kira, Wakiso District, it is a beehive of activity. Every construction stage is manned by different personnel doing different work. Randomly, what is easy to notice with the workers mixing concrete is that there are concrete portions that were not used. They are dry and abandoned on the site side.
There are also pieces of iron bars, which are approximately a metre, or less long, that remained when cutting those to be used for shaping construction columns.
“When the engineer gives me estimates of materials required, I buy and deliver them at the site because I believe it is what he needs to have the work done. When I visit the site, I find some of the materials wasted yet money was already spent to buy them,” Mugabe says.
How does the wastage come about? Bunnett Bagombeka, a managing partner and senior consultant at Franbag Bau Uganda Limited, says wastage of materials at a building site is due to several reasons:

Bad structural designs
Firstly, bad structural designs by inexperienced engineers who over dimension structural objects such as columns, beams and slabs, among others, lead to material wastage.
The fact that a structure is over designed means that the excess materials are a waste. The over design may also be a result of your engineer who is not sure of the capability of the contractor.

The engineer, therefore, intentionally overdesigns with hope that in case the contractor makes mistakes, for example in the concrete design or size of rebars, the structure would not collapse.
“Both cases portray bad engineering practices. Therefore, to get rid of wastages due to overdesign, you should employ well qualified and registered engineers who will do standardised work,” Bagombeka advises.

Poor quality materials
He also observes that use of poor quality materials is also a cause of material wastage.
Poor quality materials do not stand the test of time and are normally demolished and disposed of. For example, unseasoned timber warps or goes out of shape quickly and thus a need for replacement.
A slab or beam built with poor concrete shows early signs of cracking and may be demolished and replaced with a stronger one with time.
In this case, whatever has been demolished is wastage to the site developer or owner.

Frequent changes
At times, your frequent changes may lead to material wastage because some elements may be demolished to fulfil your desires. It is advisable to work closely with the architect and come up with an agreed final plan before the commencement of construction to avoid changes when the construction is ongoing.

Poor construction technics
Poor construction technics may lead to failure to get levels correct and this may lead to cutting off parts of structures to attain the levels. This in turn results into wastage of concrete hence cement, sand and aggregates.
“It has been observed on sites that most contractors cut bags of cement spilling off part of it when mixing concrete. These cement spills end up being a big part of cement wastage,” Bagombeka explains.

Inexperienced labour
Using inexperienced or unskilled labour (masons) may lead to poor estimation of required material for a piece of work. This results in excess concrete or cement mortar that is normally thrown away.
It is important to note that rework due to worker’s mistakes normally contributes a lot to wastage. In this respect, poor supervision of works is a big contribution to material wastage.

Poor material storage
Wrong and lack of proper material storage places leads to wastages. For example, if cement is stored in a humid store, it may harden before it is used and will become unusable.
Sand stored in an open place without protection may be washed away by heavy rains and wind. Stone and sand aggregates, when poorly stored, may be contaminated with mud and may be rejected for use in concrete. Poor storage may also lead to theft of materials, hence wastage.

Bulk purchases
In 2,000 when Ben Twinomugisha was building his country home, he bought bricks and cement in bulk because he did not want to be bothered by the engineer asking for more materials.
One day when he visited the site, he found when many bricks had been broken. “I asked the builders to gather the broken bricks in one place as I devised where I could use them. They were so many that I couldn’t just throw them away,” Twinomugisha recalls.
Bagombeka agrees that bulk purchases may lead to excess material, which results in wastage. In addition, poor material scheduling may result in wastages as some materials may expire before being used. It is, therefore, advisable to check out expiry dates of certain materials such as paint and cement before purchase to realise value for money.

How to use the wasted material

When Anthony Katabazi was building his house in Kyanja, he realised there was wasted material such as concrete and timber that had been obtained from timber cuttings at roofing level.
“The compound was not yet levelled. So, instead of hiring a grader to level the compound, I used the wasted solidified concrete and gravel to fill the gaps and pits in the compound,” Katabazi recalls.

For Ben Twinomugisha, who had remained with many half bricks when the construction was almost complete, he says he recalls using them not only to build poultry shelters but also building the boys’ quarter verandahs.
“Before I bought more bricks to complete the boys’ quarters, I tasked the engineer to make use of the half bricks that had not been used. When they were finished, I bought half a truck of complete bricks to complete the boys’ quarter verandah,” Twinomugisha says.

Since timber does not expire, Twinomugisha advises that it is better to collect and keep it in a dry place. Sooner or later, it will get used. For example, when the construction was complete at his site, when he introduced dogs few months later, he used the timber pieces that had remained to make wooden kennels.
If you are a farmer, you can as well use the timber for making poultry shelters.

Wrong supplier advice
In some instances, wrong suppliers’ advice also leads to material wastage.

This happens when the contractor finds out later after using the material that it does not match the specifications. In the end, you throw the material away.

Design errors,equipment
Also, design errors may result in material wastages. This is because the structure in error is normally demolished, while the use of defect equipment such as concrete mixers may result into a lot of wastage.
[email protected]