{"id":3877,"date":"2026-06-10T06:53:42","date_gmt":"2026-06-10T06:53:42","guid":{"rendered":"https:\/\/www.buildteam.com\/blog\/?p=3877"},"modified":"2026-06-15T13:34:13","modified_gmt":"2026-06-15T13:34:13","slug":"replacing-a-conservatory-with-an-extension","status":"publish","type":"post","link":"https:\/\/www.buildteam.com\/blog\/replacing-a-conservatory-with-an-extension\/","title":{"rendered":"Replacing an Existing Conservatory with an Extension"},"content":{"rendered":"\n

In London in 2026, replacing a conservatory with a solid extension costs roughly \u00a32,800 to \u00a35,500 per m\u00b2<\/strong> for the build, or about \u00a360,000 to \u00a3150,000 all in<\/strong> for a small-to-medium rear extension. Removing the old conservatory adds \u00a3800 to \u00a32,500<\/strong>. Like-for-like replacements often need no planning permission, but the new space must meet full Building Regulations, and a quality extension can add around 5 to 10% to a home’s value.<\/p>\n\n\n\n

Many homeowners end up with a conservatory they no longer use as intended. It becomes the place the bikes live, or where the washing dries, because it is too hot in summer and too cold to sit in through winter. Replacing that conservatory with a properly built extension is one of the most popular ways London homeowners reclaim the space, and it is usually a better long-term investment than repairing or reglazing an ageing conservatory.<\/p>\n\n\n\n

This guide covers what the work costs in 2026, whether you need planning permission, the building regulations that apply, the value it can add, and what a real conservatory-to-extension project looks like before and after.<\/p>\n\n\n\n

How much does it cost to replace a conservatory with an extension?<\/h2>\n\n\n\n
\"Conservatory<\/a><\/figure>\n\n\n\n

For a London project in 2026, budget \u00a32,800 to \u00a35,500 per square metre<\/strong> for the new extension build, depending on specification. Removing the old conservatory is a separate, smaller cost of \u00a3800 to \u00a32,500<\/strong>. Most replacement projects land in these brackets:<\/p>\n\n\n\n

Item<\/th>Indicative 2026 cost (London)<\/th><\/tr><\/thead>
Removing the existing conservatory<\/td>\u00a3800 to \u00a32,500<\/td><\/tr>
New solid extension, build only<\/td>\u00a32,800 to \u00a35,500 per m\u00b2<\/td><\/tr>
Small replacement (15 to 20 m\u00b2), all in<\/td>\u00a360,000 to \u00a3110,000<\/td><\/tr>
Medium replacement (20 to 30 m\u00b2), all in<\/td>\u00a380,000 to \u00a3150,000<\/td><\/tr>
Professional fees, planning and surveys<\/td>add 10 to 15% on top<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

London costs sit above the UK average because of labour demand, tighter site access and stricter planning. The figures above are indicative, and the real price depends far more on design and material choices than on floor area alone. For a fuller breakdown of rates by extension type, see our guide to extension costs per square metre in London<\/a>.<\/p>\n\n\n\n

The teardown itself is the cheap part. A lightweight uPVC or lean-to conservatory strips out quickly because the frame is bolted on rather than bonded into the wall. The cost sits in what comes next: foundations, structure and a build that meets current energy standards.<\/p>\n\n\n\n

Can the existing foundations be reused?<\/h3>\n\n\n\n

Sometimes, but rarely in full. Conservatory footings are usually shallow and were never designed to carry a solid, insulated structure with a tiled or warm flat roof. If a structural engineer confirms the existing base and dwarf wall are sound, you may be able to build up from the plinth using insulated studwork faced with brick, which keeps costs down. If they are not suitable, a full rebuild of the base is needed, and underpinning or new trench-fill foundations can add several thousand pounds. This is assessed with trial pits before any work is signed off.<\/p>\n\n\n\n

Is it cheaper to convert the conservatory or rebuild it as an extension?<\/h2>\n\n\n\n

A new conservatory averages around \u00a315,000 in 2026, while a solid extension costs roughly twice as much per square metre. You pay the premium for foundations, insulation and a structure that is usable every day of the year. The trade-off is straightforward: a conservatory is cheaper now, but a brick or block extension is comfortable in all seasons, lower maintenance, and counts as genuine living space when your home is valued or sold.<\/p>\n\n\n\n

If you are weighing up the wider decision of how to add space, a rear or side-return extension is not the only route. A loft conversion<\/a> adds a room without using garden space, and a basement conversion<\/a> can work where outward space is limited.<\/p>\n\n\n\n

Before and after: a real conservatory-to-extension project<\/h2>\n\n\n\n

The clearest way to picture the change is to see it. Below is a typical Build Team conservatory-to-extension conversion in London.<\/p>\n\n\n\n

\"conservatory-to-extension-before-after-london\"<\/a><\/figure>\n\n\n\n

The project at a glance:<\/strong><\/p>\n\n\n\n