One of the key decisions when planning an extension is whether to go with a flat or pitched roof. Each has distinct advantages, and the right choice depends on your property, budget and aesthetic preferences.
Flat roofs are typically cheaper to build, offer a clean contemporary look, and allow you to maximise internal ceiling height. They're the default choice for single-storey rear extensions, especially with modern materials like GRP fibreglass.
However, flat roofs have a shorter lifespan (25–40 years vs 60–100+ for pitched) and require periodic maintenance. They can also look out of place on traditional Kent properties, particularly in Conservation Areas.
Pitched roofs cost 15–25% more to build but offer a more traditional appearance, longer lifespan and better thermal performance. They also create the option for vaulted ceilings internally, which can add dramatic impact.
Planning considerations: under permitted development, single-storey rear extensions are limited to 4m in height. A flat roof makes it easier to stay under this limit while maximising internal height. Pitched roofs on extensions must not exceed the height of the existing roof.
For two-storey extensions, a pitched roof that matches the existing house is almost always the best choice — visually and practically. Most planners will expect the extension to harmonise with the original building.
At TEMBOK, we build both flat and pitched roofs to an equally high standard. We'll advise which option works best for your specific project, taking into account the property style, planning constraints and your budget.