Extension or roof extension: which suits your house?

Extension or roof extension? An extension enlarges your home on the ground floor, usually at the rear. A roof extension adds an extra storey on top of the existing roof. People often choose an extension for a bigger living room or kitchen diner, and a roof extension for extra bedrooms or a workspace without giving up garden. Which suits you best depends on your plot, the load-bearing capacity of the house, the council's rules and what you want to use the space for. Below we set out the differences.

What is the difference between an extension and a roof extension?

An extension stands on the ground and has its own foundations. It connects to the existing facade, often with a sliding door or French doors to the garden. We build an extension from design and foundations to brickwork, frames and the complete finish.

A roof extension goes on top of the house. On a house with a flat roof it is an extra storey; with a pitched roof it can mean raising the roof. The structure of the existing house then carries the extra weight. See also our service roof extension and roof terrace.

When do you choose an extension?

An extension is often the logical step if you want more living space downstairs. The kitchen moves back, the living room gets deeper and light comes in through a roof lantern or glazed doors. You keep living on one level, which is also pleasant later in life. What is more, life upstairs simply carries on during the build.

• You want a bigger living room or kitchen diner
• There is enough garden to give up a part of it
• The existing structure cannot carry an extra storey
• You may be able to build without a permit

When is a roof extension the better choice?

A roof extension makes sense if the garden is small or if you are looking for extra bedrooms, a bathroom or a study. Especially in towns with small plots, building upwards is often the only way to grow. An example is our roof terrace with a roof extension in Amsterdam, where a timber roof extension with decking as a roof terrace was built on a flat roof.

If you are torn between a dormer and a full roof extension, read dormer or roof extension. A dormer gives more headroom in one spot, a roof extension makes the whole floor usable.

Extension or roof extension: what about the permit?

A rear extension is often permit free within certain dimensions. That depends on the location on the plot, the depth, the height and your council's environmental plan. Read more about this in an extension without a permit.

A roof extension usually does require an environmental permit (omgevingsvergunning), because the outline of the house changes. The council then also looks at the streetscape. Always check with the council or via the Omgevingsloket. You will find more in the permit for a roof extension.

Roughly what does an extension or roof extension cost?

Both are bespoke work, so there is no fixed price per metre. For an extension, the foundations, the facade and the glazed doors count most. For a roof extension, the structural alterations, the lifting work and a new staircase count. Per square metre a roof extension is therefore not necessarily cheaper.

For rough price ranges, see what does an extension cost and what does a roof extension cost. Only a tailored quotation gives real clarity, because the condition of your house determines a lot.

Frequently asked questions