Common Structural Mistakes in DIY Projects (and how to avoid them)

With the rise of home renovation shows and online tutorials, it's no surprise that more and more homeowners are tackling DIY projects. While repainting a wall or replacing tiles can be a rewarding weekend job, some DIY tasks come with hidden structural risks that can lead to costly repairs, or worse, unsafe living conditions.

At Pavol Zajac Structural Engineers Ltd, we often get called in to assess damage that could have been prevented with the right guidance. Here are some of the most common structural mistakes we see in DIY projects, and how you can avoid them.

1. Removing Load-Bearing Walls Without Assessment

One of the most frequent and dangerous DIY mistakes is knocking through walls to create an open-plan space without checking if the wall is load-bearing.

Why it's a problem:

Load-bearing walls support the weight of the floor or roof above. Removing them without proper support can lead to sagging floors, cracked ceilings, or even collapse.

How to avoid it:

Always consult a structural engineer before removing any wall. We'll assess the load and design appropriate support such as an RSJ (rolled steel joist) beam.

2. Incorrect Installation of RSJ Beams

Some homeowners purchase and install steel beams themselves, often based on online advice or builder recommendations.

Why it's a problem:

Every property is different. An RSJ that works in one house might be inadequate, or excessive in another. Incorrect sizing, bearing or placement can lead to long-term structural damage or regulatory issues.

How to avoid it:

Get structural calculations done by a qualified engineer. We provide detailed drawings and specifications tailored to your home.

3. Underestimating Foundation Work

DIY extensions or garden rooms often rely on basic or shallow foundations.

Why it's a problem:

Poor foundation design can lead to cracking, subsidence, or uneven settlement, especially on clay soils or near trees.

How to avoid it:

Have a structural engineer assess the ground and site conditions and recommend the correct foundation depth and type.

4. Overloading Floors and Roofs

Whether it's converting a loft into a bedroom or installing a freestanding bathtub upstairs, many homeowners overlook how much additional weight they're adding to floors or roof structures.

Why it's a problem:

Overloading can cause deflection, creaking floors, and eventual structural failure.

How to avoid it:

Before making changes that add weight, have an engineer review the load-bearing capacity of your floors or rafters.

5. Ignoring Lateral Support in Loft Conversions

DIY loft conversions often remove internal bracing to create space.

Why it's a problem:

Those braces are crucial for keeping the roof structure stable. Removing them without compensation can lead to spreading walls or roof sag.

How to avoid it:

We'll design a structural solution, like steel cross-beams or collars to preserve both space and safety.

Don't Let a DIY Job Turn Into a Disaster

Taking pride in your home is a wonderful thing, but when it comes to structural elements, it pays to involve a professional. A quick consultation with a structural engineer at the start of your project can save you from expensive repairs down the line and ensure your home remains safe and sound.

Thinking about a renovation or structural change?

Get in touch with Pavol Zajac Structural Engineers Ltd for expert advice, calculations, and peace of mind.

Contact us today to discuss your plans.