You want more space and more value. Do you build out with an extension, or up with a loft conversion? Here is a straight comparison for homeowners in Solihull, Birmingham and the wider West Midlands.
Value added: the honest figures
Based on the last three years of Solihull sales data and typical build costs:
Single-storey rear extension
- Cost: £55k–£85k for a good-sized 25 m² extension
- Value added on a £450k Solihull home: £65k–£95k
- Return on investment: typically breaks even or slight profit
Loft conversion (dormer)
- Cost: £50k–£75k for a full dormer conversion with en-suite
- Value added on a £450k Solihull home: £70k–£95k
- Return on investment: typically breaks even or slight profit — but almost always adds a bedroom, which is the specific factor that pushes homes into a higher buyer bracket
Winner on pure value: loft conversion, by a small margin, because it usually adds an actual bedroom (3-bed to 4-bed transition adds far more than mere square metres).
Which one suits which property type?
1930s Solihull semi with generous rear garden
Both options work. A rear extension is often cheaper per m² but takes garden space. A loft dormer preserves the garden. If the loft has good head-height already, dormer wins.
Victorian terrace in Moseley/Kings Heath
Rear extension usually. Terraces often have limited loft headroom because of shallow original roof pitches. A rear extension into the (typically long) garden is the standard move.
1960s/70s Solihull detached
Depends on which room you actually need. If a bigger kitchen: rear extension. If more bedrooms: loft.
Conservation area properties
Loft conversions face more planning challenges here (especially front-facing dormers). Rear extensions can be easier.
Disruption during the build
This surprises clients. Loft conversions are typically less disruptive because the work happens above the living space. You keep using your kitchen and living areas throughout. Rear extensions usually involve opening up the back of your house at some point, which is significantly more intrusive.
Planning permission
Both often fall under Permitted Development Rights, subject to size limits:
- Loft: 40 m³ for terraces, 50 m³ for semi-detached and detached (added volume)
- Single-storey rear: 3m (attached) or 4m (detached) under standard PDR, up to 6m/8m under prior approval
Conservation areas and Article 4 directions remove PDR in some Solihull neighbourhoods.
Long-term flexibility
An extension gives you more flexibility to reconfigure downstairs (open plan, walk-through, bi-fold onto garden). A loft conversion gives you a fixed extra bedroom / office / studio.
Our recommendation
If you can afford both, do both — but not at the same time. Loft first because it’s less disruptive and adds the “bedroom count” that most drives home value. Rear extension second to transform how you use downstairs. Between the two, you have effectively rebuilt the useful space of the house without moving.
Free consultation
We visit properties across Solihull, Birmingham and Warwickshire for a free initial consultation covering both options. Call 01527 521835 or use our contact form.
Serving homeowners across Solihull, Birmingham, Worcester, Redditch and the wider region.