Opening up a house: removing load-bearing walls safely

Many older Cape Town homes were built with separate kitchens, dining rooms and lounges. Today, most families want open-plan living, with the kitchen at the centre and a connection to the garden. That usually means taking out walls, and some of those walls are holding up the house.

How to tell if a wall is load-bearing

Only an engineer can say for certain, but there are clues:

• External walls are almost always load-bearing.
• Walls running perpendicular to the ceiling joists or roof trusses often support them. Look in the roof space.
• Walls directly under another wall upstairs usually carry the load from above.
• Walls with a thick foundation underneath, or that are thicker than other internal walls, may be structural.
• Walls in older houses are more likely to be load-bearing, because older roofs were often supported on internal walls.

Even walls that do not carry the roof can provide stability to the building. Never assume a wall can be removed.

What happens when a load-bearing wall is removed

The load the wall carried must be transferred to something else. Usually, a new beam is installed in place of the wall, sitting on supports at each end. The supports transfer the load down to foundations that can carry it.

The beam can be:

• A steel beam, the most common choice, often hidden in the ceiling or boxed in
• A reinforced concrete beam, cast in place
• A timber or engineered timber beam, for lighter loads

The engineer sizes the beam and checks whether the existing foundations under the supports are adequate. Sometimes new foundations are needed.

Approvals

Removing a load-bearing wall is a structural alteration. It needs:

• An engineer’s design and appointment
• Approved building plans in most cases
• An engineer’s inspection during the work and a completion certificate afterwards

Doing this work without approvals can cause problems when you sell the house, and much worse problems if the structure fails.

How the work is done

1. Temporary support. Before the wall is touched, the structure above is supported with temporary props.
2. Opening up. The wall is carefully demolished, with dust control in place.
3. New supports and foundations. New piers or columns, and foundations if needed, are built.
4. Installing the beam. The beam is installed and packed tight to the structure above.
5. Removing the props, only once the new structure is complete and approved.
6. Making good. Ceilings, floors and walls are repaired, and the beam is boxed in and finished.

Services in the wall

Walls often hide electrical cables, plumbing and sometimes gas pipes. These must be found and rerouted before demolition.

Floors and ceilings

Where two rooms are joined, the floors and ceilings are rarely at the same level or finished in the same way. Plan for a new continuous floor finish and new ceilings, so the new space looks like it was always one room.

Opening up a house

Done well, removing walls transforms how a home feels: more light, better flow and a kitchen that connects to family life. Our full home renovation included structural alterations to open up the living areas. If you are thinking about opening up your home, talk to us. We will work with an engineer to do it safely.