Loft Conversion Cost in Cardiff: 2026 Price Guide
08 Aug 2026
- Rooflight (Velux) conversion: £18,500-£32,500
- Rear dormer conversion: £32,500-£47,500
- Hip-to-gable or mansard: £47,500-£71,000+
Cardiff's terraced roof stock
The Victorian terraces across Roath and Cathays typically have steeper roof pitches than later housing, which can mean less dormer volume is needed to hit a comfortable head height - useful when Wales' own permitted development rules, distinct from England's, set the volume limits that apply.
Party walls
Most loft conversions on Cardiff's terraced streets involve a shared party wall, meaning a Party Wall Agreement with neighbours is required before work starts under the same UK-wide Party Wall etc. Act 1996 that applies regardless of the separate Welsh planning system - budget several weeks for this.
Pontcanna and conservation status
Inside Pontcanna's conservation area, even a rear-facing dormer not visible from the street can face closer scrutiny than the same job elsewhere in Cardiff - worth checking your property's specific status with Cardiff Council before committing to a design.
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Frequently asked questions
How much does a loft conversion cost in Cardiff?
A rooflight (Velux) conversion runs £18,500-£32,500, a rear dormer £32,500-£47,500, and a hip-to-gable or mansard conversion £47,500-£71,000+.
Do I need a Party Wall Agreement for a Cardiff loft conversion?
In most cases yes - most loft conversions on Cardiff's terraced streets involve a shared party wall, and the UK-wide Party Wall etc. Act 1996 applies regardless of the separate Welsh planning system.
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