This is one of the first decisions homeowners face when they start planning an extension, and it is rarely as simple as picking whichever is cheaper. Single-storey and double-storey extensions solve different problems, and the right choice depends on what your house actually needs.
What a Single-Storey Extension Is Good For
- Extending a kitchen or living space at the rear of the house
- Properties where the upstairs layout already works and only downstairs feels cramped
- Homes where a two-storey extension would overshadow neighbouring gardens, which can complicate planning
- Projects where budget is more limited, since a single storey costs significantly less per square metre than adding a second floor
Single-storey extensions are also more likely to fall under permitted development rules, which can mean a faster start on site.
What a Double-Storey Extension Is Good For
- Adding a bedroom or bathroom upstairs alongside more living space downstairs
- Properties where the footprint is limited and building outwards on one level is not enough to solve the space problem
- Homeowners planning to stay long-term and wanting to add significant value in one project rather than extending twice
A double-storey extension almost always costs more per square metre than a single storey, since it needs additional structural support, but the cost per square metre of extra floor space is usually lower than building a single-storey extension of equivalent size, because you are sharing one roof and one foundation across two floors.
Cost Comparison in Real Terms
For a typical extension in Leicestershire or Rutland:
- Single-storey (20 to 25 square metres): £40,000–£60,000
- Double-storey (equivalent footprint, two floors): £70,000–£110,000
The double-storey option roughly doubles your usable floor space for less than double the cost, which is why we often recommend it to clients who are confident they will stay in the property long-term.
What Actually Determines the Right Choice
- How much additional space you need, and whether it is downstairs, upstairs, or both
- Your garden size and how much of it you are willing to give up
- Whether neighbouring properties or planning constraints make a two-storey build difficult
- Your budget, both for the build itself and for any additional groundwork a heavier structure requires
There is no universally right answer here, only the right answer for your specific house and how you plan to live in it. Get in touch and we will survey your property and talk through which option makes sense before you commit to either.