20, Allen Street, Mountain Ash occupies a 120 m² plot as recorded by HM Land Registry.

Of the 32 other houses in this postcode, 28 have recorded plot sizes, and this one ranks as the 20th largest.

20, Allen Street, Mountain Ash has an Energy Performance Rating (EPC) of D. This is based on the most recent assessment, dated 02 Apr 2026.

The property is connected to mains gas and has fully double glazed windows. It is heated using a boiler and radiators (mains gas).

20, Allen Street, Mountain Ash last changed hands on 14th November 2016, selling for £60,000. The transaction was logged as a freehold house by HM Land Registry.

That is its only recorded sale since 1995.

The market for similar properties has risen by 73.7% since November 2016.

• Sold Nov 2016£60,000

Land Registry records and our Estate Agent network show 258 sales of comparable properties within 590 metres of 20, Allen Street, Mountain Ash since 2020.

Most recently, 59, Arnold Street, Mountain Ash, CF45 4LF, a freehold house, sold at £140,000 on the 17th October 2025.

Read more about house prices in CF45.

• Sold Oct 2025£140,000 | 3 Bed House59, Arnold Street, Mountain Ash, CF45 4LF59, Arnold Street, Mountain Ash, CF45 4LF
• Sold Jul 2025£115,000 | 3 Bed House13, London Street, Mountain Ash, CF45 4BN13, London Street, Mountain Ash, CF45 4BN
• Sold Jul 2025£125,000 | 3 Bed House50, Phillip Street, Mountain Ash, CF45 4BG50, Phillip Street, Mountain Ash, CF45 4BG
• Sold Apr 2025£82,600 | 3 Bed House54, Arnold Street, Mountain Ash, CF45 4LF54, Arnold Street, Mountain Ash, CF45 4LF
• Sold Oct 2024£80,000 | 3 Bed House18, Phillip Street, Mountain Ash, CF45 4BE18, Phillip Street, Mountain Ash, CF45 4BE
• Sold Oct 2024£85,000 | 3 Bed House3, London Street, Mountain Ash, CF45 4BN3, London Street, Mountain Ash, CF45 4BN
• Sold Sep 2024£85,000 | 3 Bed House42, Allen Street, Mountain Ash, CF45 4BB42, Allen Street, Mountain Ash, CF45 4BB
• Sold Jul 2024£140,000 | 3 Bed House26, Phillip Street, Mountain Ash, CF45 4BE26, Phillip Street, Mountain Ash, CF45 4BE
• Sold Jan 2024£105,000 | 3 Bed House12, Phillip Street, Mountain Ash, CF45 4BE12, Phillip Street, Mountain Ash, CF45 4BE
• Sold Jun 2023£117,500 | 3 Bed House21, Copley Street, Mountain Ash, CF45 4AS21, Copley Street, Mountain Ash, CF45 4AS
• Sold Jul 2022£135,000 | 3 Bed House17, Allen Street, Mountain Ash, CF45 4BD17, Allen Street, Mountain Ash, CF45 4BD
• Sold Jun 2022£129,995 | 3 Bed House4, Copley Street, Mountain Ash, CF45 4AS4, Copley Street, Mountain Ash, CF45 4AS
• Sold Mar 2022£115,000 | 3 Bed House56, Phillip Street, Mountain Ash, CF45 4BG56, Phillip Street, Mountain Ash, CF45 4BG
• Sold Feb 2022£127,000 | 3 Bed House14, Copley Street, Mountain Ash, CF45 4AS14, Copley Street, Mountain Ash, CF45 4AS
• Sold Sep 2021£107,500 | 3 Bed House37, Arnold Street, Mountain Ash, CF45 4LF37, Arnold Street, Mountain Ash, CF45 4LF
• Sold Jun 2021£120,000 | 3 Bed House4, Phillip Street, Mountain Ash, CF45 4BE4, Phillip Street, Mountain Ash, CF45 4BE
• Sold Jun 2021£80,000 | 3 Bed House24, Arnold Street, Mountain Ash, CF45 4LF24, Arnold Street, Mountain Ash, CF45 4LF
• Sold Mar 2021£65,000 | 3 Bed House23, Phillip Street, Mountain Ash, CF45 4BE23, Phillip Street, Mountain Ash, CF45 4BE
• Sold Aug 2020£72,000 | 3 Bed House58, Phillip Street, Mountain Ash, CF45 4BG58, Phillip Street, Mountain Ash, CF45 4BG
• Sold Jul 2020£112,000 | 3 Bed House51, Phillip Street, Mountain Ash, CF45 4BG51, Phillip Street, Mountain Ash, CF45 4BG

Our analysis of the public data ranks 20, Allen Street, Mountain Ash as the 32nd largest and the 46th most expensive of the 63 addresses on Allen Street, Mountain Ash, CF45.

Against the CF45 postcode district average, it is £29k less expensive than the typical property.

• Mountain Ash

  |

  400 m away
• Fernhill

  |

  1.2 km away
• Penrhiwceiber

  |

  2.1 km away

Environment Agency data suggests this area has a Very Low risk of flooding.