{"id":2177,"date":"2026-09-07T09:50:32","date_gmt":"2026-09-07T09:50:32","guid":{"rendered":"https:\/\/www.yopa.co.uk\/homeowners-hub\/?p=2177"},"modified":"2026-09-07T11:25:03","modified_gmt":"2026-09-07T11:25:03","slug":"a-guide-to-under-garden-basement-extensions","status":"publish","type":"post","link":"https:\/\/dy36.stage.yopa-dev.co.uk\/homeowners-hub\/a-guide-to-under-garden-basement-extensions\/","title":{"rendered":"A guide to under-garden basement extensions"},"content":{"rendered":"\n

When you are\nbursting at the seams and space (or lack of it) is a serious issue, the age-old\nquestion of a house move versus an extension to your current home is a common\nquandary for many of us. <\/p>\n\n\n\n

A new house may give you that added bedroom\/study\/garden space you need straight off the bat, but upsizing to a bigger property can increase your mortgage payments and outgoings significantly, not to mention the added upfront expenses of moving home<\/a> such as solicitor and removal fees, stamp duty and surveys, said to cost an average of around \u00a313,000. <\/p>\n\n\n\n

When it comes\nto extending your own property, this may come at a financial cost and the\nshort-lived inconvenience of onsite building work, but it could pay dividends\nwhen it comes to adding resale value to your property, not to mention the\nmassive benefits for your current lifestyle. You are also likely to be paying\nless overall than it would cost to find a house in your preferred area with the\nspace you need. <\/p>\n\n\n\n

Whilst a loft conversion<\/a> might be the easiest and most affordable option (which can also add around 20% in value to your home), this isn\u2019t an option for every property if your supporting walls are not sufficiently load-bearing or you don\u2019t have enough headspace. <\/p>\n\n\n

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Get a rough estimate of your home's value now.<\/p> <\/div>\n <\/div>\n<\/div>\n <\/a>\n <\/div>\n

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Book an appointment with your local Yopa agent.<\/p> <\/div>\n <\/div>\n<\/div>\n <\/a>\n <\/div>\n<\/div>\n\n\n\n\n

Extensions to\nthe side, front or rear of your property can be a good option, however these\ntypes of extension are governed by a range of restrictions<\/a> when it comes to size, space and\nproximity to nearby properties. If you are limited with the space surrounding\nyour property that precludes these types of extension, then going underground\nmay be a good alternative.  <\/p>\n\n\n\n

When it comes\nto a subterranean conversion, if you do not have existing cellar space beneath\nyour property then adding a basement area retrospectively can be very costly\nsince you will need to dig into the existing foundations and underpin the house\nto do so. As a general rule, this will cost around \u00a32,500 – \u00a33,000 per square\nmetre versus \u00a3900 – \u00a31,400 per square metre for the conversion of an existing\ncellar space with no structural changes. As such, a more affordable alternative\nis a basement extension beneath your garden or driveway which can cost around\n50% less. <\/p>\n\n\n\n

Whilst it may\nsound a bit superhero-esque to have an underground \u2018bat cave\u2019, basement\nextensions under gardens and driveways have actually grown in popularity in the\nlast 20 years or so, particularly in cities like London where space is at a\npremium. And whilst it may cost slightly more than your average property\nextension depending on the type of land and property you own; the advantages\ncan be huge.  <\/p>\n\n\n\n

Unlike a\ntraditional basement extension, extending under your garden allows the\nopportunity to easily incorporate natural light with the addition of walk-on\nroof lights, lightwells and lower terraces which also create separate pockets\nof private, outdoor space. There is also less impact to your neighbours during\nand after the build than with a conventional extension and less structural risk\nto both your own and neighbouring properties than you would have with a traditional\nbasement extension underneath your property. <\/p>\n\n\n\n

So, you\u2019re\nsold on an under-garden extension. How much will it cost? <\/strong><\/h3>\n\n\n\n

Generally\nspeaking, it will cost\naround \u00a31,500 \u2013 \u00a32,000 per square metre to create a new basement extension\nunder your garden. However, as with all extensions, there are a number of\nfactors that will affect the cost of an under-garden extension:<\/p>\n\n\n\n