10 Common Construction Mistakes and How to Avoid Them

Construction mistakes are one of the biggest reasons people lose money, delay projects, or end up with weak buildings. Most of these mistakes are caused by lack of knowledge and poor planning.

If you are planning to build a house or are already building, understanding these 10 common construction mistakes will help you save money, protect your investment, and build a safer home.

Table of Contents

1. Lack of Proper Planning

One of the most common construction mistakes is starting work without a clear plan.

I once heard of a client who approached a fundi on a Monday with just a vision of a building and the fundi started execution of the project the next day without a proper laid out plan. This left me wondering at the kind of project the fundi delivered.

Why this is a problem

Work is done randomly with just random thoughts and ideas. This obviously produces shoddy work
Costs increase unexpectedly since there was no proper planning done in the first place to anticipate such occurrences
Materials are wasted due to lack of proper planning
Construction delays become frequent because there are no properly laid out stages to be followed in project execution

How to avoid this mistake

Preparation of a clear construction plan which helps to identify beforehand any challenges that may come along the way
Know the construction stages so that you can arrange them in a chronological order
Plan materials and labour before starting to have a smooth flow of the construction process

Executing construction without a proper plan is like moving without a proper direction of where you’re going. It’s so draining and expensive.

2. Ignoring Soil Conditions and Site Investigation

Almost all construction in the world begins on land. However, many people start construction without checking the soil condition of their land which is very risky.

An important fact to note is that different soils have different compositions which support buildings differently.

Common results of ignoring soil conditions

Cracked walls as a result of expansion and contraction of the soils
Sinking foundations when then building tries to settle
Expensive repairs which might come later on after construction

How to avoid this mistake

Carry out a basic soil investigation. A soil investigation might look expensive on face value but it will save you the would be repercussions in the future.
Consult an engineer before foundation design to help in the technical part from a professional point of view

Understanding the soil where to set up the construction leads to a strong building.

3. Using the Wrong Foundation Type or Depth

A foundation is the point of contact between the building and the soil. It carries the entire weight and load on a building and safely distributes it to the soil.
This means that any mistakes here can be very dangerous.

Common foundation mistakes

Shallow foundations in poor soils
Wrong foundation type for the particular soil
Poor compaction of foundation trenches which lead to improper settlement of the building

Consequences

Structural cracks in the building
Uneven settlement of the building
Risk of collapse of the building since the foundation cannot support the building

How to avoid this mistake

Follow approved structural drawings
Use the correct foundation depth that is recommended in the building codes
Ensure proper compaction of the foundation before casting concrete to prevent uneven settlement of the building

4. Using Wrong Concrete Mix Ratios

The strength of concrete depends on the correct mix of cement, sand, and aggregates.

Common concrete mistakes

Too much or too less of cement, aggregate, and water
Guessing mix ratios
Improper curing time like starting blockwork on a slab that has only spent two days after casting

Effects

Weak concrete
Cracking of concrete components such as slabs, beams, columns
Reduction in the building lifespan

How to avoid this mistake

Use recommended concrete mix ratios for specific concrete components
Measure materials properly without assuming
Avoid adding excess water to make the concrete workable. Always use the recommended quantities
Allow proper curing of the concrete through using the recommended curing periods

5. Buying Substandard or Fake Materials

There is a common phrase used in construction which is “even this can work”. It’s a phrase used commonly to refer to low-quality materials. These materials are cheap hence the attraction but are one of the causes of construction failure.

Some common substandard materials

Fake cement
Weak steel reinforcement
Untreated timber
Poor-quality bricks or blocks

Why people make this mistake

Trying to save money since they are labelled as substitute goods
A lack of material knowledge leads to purchase of whatever is available in the market

How to avoid this mistake

Get trusted suppliers for material supply
Check material standards before purchase to ensure that the right materials are acquired
Consult professionals who know the correct materials before purchasing

6. Poor Site Supervision

Most clients like shortcuts whereby they leave construction work entirely to fundis without supervision. The fundis without a professional supervisor might pose as a cheaper option but this is a serious mistake.

Problems caused by poor supervision

There is a lot of shoddy work since drawings aren’t followed
Material theft is very common due to lack of supervision
Poor workmanship since the fundis do whatever they want

How to avoid this mistake

Hire a professional site supervisor who knows what they are doing
Make sure you ensure regular inspections to make sure that what is required is what is being done on site
Make a thorough follow up on daily site activities to be updated on the site progress

7. Making Design Changes During Construction

Changing designs after construction has started is very costly.

Common design changes

Changing roof type from one type to another for example from a flat roof to a hip roof type
Subtracting or adding extra rooms

Why this is a problem

Wasted materials due to demolitions
Increased labour costs since labour is needed to effect the changes
Project delays since a lot of time is wasted on the changes

How to avoid this mistake

Ensure to finalize designs before construction takes place
Think carefully about future needs of the building so that they are put under consideration before the construction starts

8. Poor Drainage Planning Around the Building

Water is life but it is one of the biggest enemies of buildings because it drains life out of them.

Common drainage mistakes

Absence of surface drainage as running water is left to find its course
Poor slope around the building which leads water towards instead of away from the building

Effects

It leads to foundation weakening due to the infiltration of the water
It leads to damp walls as the water moves up through the walls
There is a long-term structural damage as the water continues to weaken the building components

How to avoid this mistake

Provision of proper drainage slopes to ensure proper flow of surface water away from the building
Directing water away from the foundations to keep them free from water likely to make them weak
Installation of drainage channels where necessary

9. Underestimating Construction Costs

Getting an actual value of the construction cost might be impossible but getting an approximate value to give a range to work with is not impossible.
Often many people underestimate how much construction will cost which can be of a great effect to the project.

Why this happens

Through guessing material quantities without proper calculations
Through ignoring hidden costs like costs of approvals, plans, supervisions, etc
Absence of a contingency budget to cater for unexpected outcomes

Effects

It leads to project delays since materials can get done unexpectedly
There are poor quality finishes since the available materials have to be used minimally
Construction stopping halfway due to abrupt extinguish of materials

How to avoid this mistake

Prepare accurate cost estimates not assumptions
Consider every project as unique. Quantities that worked on a past project might not be the same on the current project
Always include a 10-15% contingency to cater for other and unexpected expenses that might come up
Be updated of the current prices of materials
Track expenses regularly to know if they are as expected

10. Rushing Construction Work

Trying to finish construction too fast often leads to poor quality.

Some common rushed activities

Plastering before walls dry
Roofing before proper wall curing
Skipping curing of concrete like a common case of starting blockwork before the slab cures

Effects

Cracks since the materials aren’t allowed to bond well due to lack of drying time
Weak concrete since it’s subjected to loads when not yet ready
Poor finishes which can easily peel off

How to avoid this mistake

Allow enough time for each stage to effectively take place
Follow the recommended construction procedures in the code

Conclusion

Building a house is too important to rely on guesswork. When you avoid these common construction mistakes, you save money, protect your investment, and build a safer home that you are proud of and can live in for a long period of time.

Building right the first time is always cheaper.

Planning to build or already building?
Explore our other construction guides and free calculators to estimate materials correctly, control costs, and avoid costly construction mistakes.