3 William Street, Ystradgynlais, Swansea, SA9 1AT
About 3 William Street
3 William Street is an end-of-terrace house in Ystradgynlais, Swansea, Swansea (SA9 1AT). It has a recorded floor area of 87 m² (around 936 sq ft), construction records dating it to 1900-1929 and council tax band B. The latest certificate (November 2018) shows an E (score 45), well below the UK norm with real room to improve. The recommended improvements would lift it to B (score 85), a 3-band jump.
Across 1997–2019, sale prices on this property compounded at 3.8% per year. Today's modelled estimate of £155,000 sits 82.4% above the 2019 sale of £85,000. It lags the bulk of the postcode on energy efficiency (less efficient than 77% of similar EPCs). Last sale on file: £85,000 in April 2019.
Know exactly what you're buying at 3 William Street
Before you offer, see what the listing won't tell you, the true value, the red flags and the full history.
Already flagged here
Launch offer · save £5
Valuation
against the asking price
Risks
planning & flood
Sold prices
similar homes nearby
Trends
the local market
Energy performance
3 William Street's carbon output runs well above what efficient homes in the postcode produce.
EPC Rating
Planning history
3 William Street has no planning applications on record.
Notable planning nearby
2applications of note in the surrounding area
We flagged 1 thing worth checking at 3 William Street
Independent checks surfaced things a buyer would want to understand before offering. The report explains each one in full, with the underlying data and what to ask.
- Larger development activity nearby
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Sales history & valuation
3 William Street has more than doubled in price since the earliest registered sale in 1997.
£155,000
Modelled from EPC, postcode comparables and a sale-price growth of 3.8% per year over 22 years.
£85,000
Growth on file: 3.8% per year over 22 years.
Sales timeline
2 April 2019Most recent
£85,000
+123.7%over 21 years1 September 1997
£38,000
Median price across the last 5 sales in SA9 1AT: £127,000 (2025–2019).
Nearby sales in SA9 1AT
2 William Street, Ystradgynlais, Swansea, SA9 1AT
Sold Jul 2025
£209,95020 William Street, Ystradgynlais, Swansea, SA9 1AT
Sold Dec 2023
£125,00015 William Street, Ystradgynlais, Swansea, SA9 1AT
Sold Mar 2021
£127,000Ty Gardd, William Street, Ystradgynlais, Swansea, SA9 1AT
Sold Nov 2019
£235,00022 William Street, Ystradgynlais, Swansea, SA9 1AT
Sold Sept 2015
£84,000
Everything we know about 3 William Street, in one report
What it's really worth, what could be wrong, and the planning, sales and area data in full.
What we flagged
- Larger development activity nearby

Versus other William Street homes
On epc rating, 3 William Street runs well behind the street norm.
Price per m²
£977
Street avg £1,109
Floor Area
87 m²
Street avg 87 m²
Habitable Rooms
5 rooms
Street avg 4 rooms
CO₂ Emissions
6.6 t/year
Street avg 4.8 t/year
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The neighbourhood at a glance
Crime
6/mo
Steady year-on-year across the wider district.
Nearest stop
0.1 km
Glanrhyd Hospital — bus stop.
Go deeper on the local area
The full report breaks down crime, transport links, schools and air quality in depth.