21a, Catherine Road, Surbiton, KT6 4HA

21a is a detached house in Surbiton (KT6 4HA). It has a recorded floor area of 94 m² (around 1012 sq ft) and construction records dating it to 1900-1929. The latest certificate (April 2017) shows a D (score 59), a step below the typical UK home. When first surveyed in October 2012 the rating was F, the property has climbed 2 bands since. Between certificates, hot-water efficiency went from Poor to Good and main heating went from Average to Good. The recommended improvements would push it to C (score 78). At 94 m² this is the 24th smallest of 34 units on EPC record in the building, where floor areas span 34–345 m². The building's EPC ratings span G to C across 34 units on file.

At 94 m² it's 25.3% larger than the typical home in the postcode (75 m² median across 33 EPCs). Across 2013–2018, sale prices on this property compounded at 11.9% per year. On a £-per-square-foot basis, the last sale (£565/sq ft) was about 69.6% above the typical sold price in the postcode. Last sold in January 2018, so it's been off the market for around 8 years.