When it comes to issues that reduce the value of a property, we’re all familiar with major problems such as subsidence and knotweed, but did you know that having an old or disused swimming pool can knock almost a fifth off your home’s market value? That’s according to new research from Yopa, the full-service estate agents, that reveals 12 things that will reduce your home’s value by as much as -20%.

Yopa has looked at 12 of the worst offenders when it comes to things that can devalue your home and what that dent comes to in the current market based on the average UK house price.

Subsidence is one of the worst things that can happen to a property. It means that your home is suffering from severe structural damage that will be expensive to correct and as such reduces the market value of the property by an average of -20%. Based on the current average UK house price of £268,319*, this is equivalent to a loss of -£53,664.

Japanese Knotweed is another well-known villain in the world of property values – an invasive and destructive plant that can cause serious structural damage and is incredibly difficult to get rid of – cuts an average of -15% (-£40,248) from a property value. But this is actually less than the loss caused by a swimming pool.

You may think that a swimming pool adds to a property’s value, but if your property has one that is old or unused it will actually remove an average of -19.6% (-£52,591) from the price you can expect to achieve. This is due to the money that the new owner will have to spend filling in and covering the old pool, or at the very least modernising it.

Nearby pylons, powerlines, phone towers and wind turbines are another big turn-off for buyers, especially if they’re visible from the property. That’s why having anything like this near the home can reduce its market value by -14% (-£37,565).

Living on a flood plain or in an area with high risk of flooding can reduce the value by-13.6% (-£36,491), and there are also things completely unrelated to your property that can slash its value.

For example, buyers hate it when neighbouring properties are in a state of disrepair (-11%, or -£29,515), and if you’re unlucky enough to have bad or nuisance neighbours, the potential stress this could cause new owners cause your home’s market value to fall by -10% (-£26,832).

Other issues that will reduce your asking price include the house or garden being messy, unkempt or overgrown (-8.2%, or -£22,002); a lack of available parking (-6.8%, or -£18,246); and even having an ‘unlucky’ house number such as 13 (-6%, or -£16,099).

Living in a flight path can cut value by -5.5% (-£14,758), and nearby power stations can reduce it by -5% (-£13,416).

Yopa’s National Franchise Director, Steve Anderson, commented:

“Average house prices are a useful guide when it comes to valuing a property, but in reality your home is only worth as much as someone is willing to pay for it.

“While some of the money-losing issues we’ve discovered can be remedied before you place the house on the market – some easily such as general untidiness and poor upkeep, others with more difficulty such as subsidence and knotweed – the rest are largely out of your control.

“It’s hard to avoid if you live under a flight path, have pylons located nearby, or, perhaps worst of all, bad neighbours. But it’s nonetheless true that this can severely impact your property value.

“If any of these things apply to your home, when it comes to selling, it’s vital that you do everything you can to present it in the best light possible and hope that buyers fall in love with it so much that they’re willing to overlook any wider issues. This means ensuring the house is clean and tidy inside and out, decluttered and bathed in natural light to demonstrate each room’s full potential. If you do all of these things, a good estate agent who knows the local market well should be able to guide you towards achieving a good price.”

Data tables and sources

*Average UK house price sourced from the UK House Price Index (Feb 2025, latest available)
Full data tables and sources can be viewed online, here.