15 Allen Close, Old St Mellons, Cardiff, CF3 5DH
About 15 Allen Close
15 Allen Close is a detached house in Old St. Mellons, Cardiff, Cardiff (CF3 5DH). It has a recorded floor area of 117 m² (around 1259 sq ft), construction records dating it to 2003-2006 and council tax band F. The latest certificate (July 2015) shows an E (score 52), well below the UK norm with real room to improve. The recommended improvements would lift it to B (score 85), a 3-band jump. The latest certificate is from July 2015, so improvements made since then won't be reflected.
It hasn't traded since September 2003, a hold of 23 years that's notably long for the area. At 117 m² the property is well over the postcode median (90 m² across 24 EPCs), placing it in the larger end of the local stock. On energy efficiency it sits in the bottom 10% of properties in this postcode — significant headroom for improvement. Across 1997–2003, sale prices on this property compounded at 8.3% per year. Today's modelled estimate of £434,000 sits 117% above the 2003 sale of £199,995.
Energy performance
15 Allen Close sits at the bottom of the postcode for energy efficiency — meaningful headroom to improve.
EPC Expired
This certificate is over 10 years old and is no longer valid.Expired 28 Jul 2025
EPC Rating
Certificate validity
Expired on 28 July 2025
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Planning history
15 Allen Close has no planning applications on record.
A planning report still maps activity across the surrounding area and reads this property's extension & conversion potential.
Sales history & valuation
15 Allen Close's estimated value is more than triple its earliest registered sale price (1997).
£434,000
Modelled from EPC, postcode comparables and a sale-price growth of 8.3% per year over 6 years.
£199,995
Growth on file: 8.3% per year over 6 years.
Sales timeline
24 September 2003Most recent
£199,995
+61.3%over 5 years25 September 1997
£124,000
Median price across the last 5 sales in CF3 5DH: £258,000 (2025–2020).
Nearby sales in CF3 5DH
31 Allen Close, Old St Mellons, Cardiff, CF3 5DH
Sold Jun 2025
£418,5003 Allen Close, Old St Mellons, Cardiff, CF3 5DH
Sold Aug 2024
£480,00020 Allen Close, Old St Mellons, Cardiff, CF3 5DH
Sold Apr 2024
£195,00038 Allen Close, Old St Mellons, Cardiff, CF3 5DH
Sold Apr 2022
£258,00037 Allen Close, Old St Mellons, Cardiff, CF3 5DH
Sold Dec 2020
£248,000
Versus other Allen Close homes
On co₂ emissions, 15 Allen Close runs well behind the street norm.
Price per m²
£1,709
Street avg £2,345
Floor Area
117 m²
Street avg 99 m²
Habitable Rooms
7 rooms
Street avg 6 rooms
CO₂ Emissions
6.5 t/year
Street avg 3.5 t/year
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The neighbourhood at a glance
Crime
242/mo
Falling year-on-year across the wider district.
Nearest stop
0.2 km
Llaneirwg Way — bus stop.
Go deeper on the local area
A Local Area report breaks down crime, transport links, schools and air quality in depth.







