Wraparound extensions

This would totally depend on the design of your extensions, but structurally a wraparound can wind up being more expensive due to the complexity of needing to remove and re-support your building’s structure. A wraparound normally requires quite a lot of steelwork to take out multiple former external walls, which can add to the cost.

The cost of a wraparound extension can vary depending on your plans. Having worked on hundreds of wraparound extensions, Resi knows roughly how much it will cost according to what you want.

On average, a standard L-shaped wraparound costs between £100,000 and £200,000. Larger wraparounds with high-spec kitchens are more, anywhere from £150,000 to £280,000. And much more premium builds including structural glazing and luxury finishes can reach £200,000 to £400,000.

If you’re based in London and the surrounding areas, you’ll most likely land at top end of those brackets. For advice on how to finance your home extension, the Resi Finance team can lay out your options.

Adding a wraparound extension is a big step, so it’s worth weighing the pros and cons carefully. Think about the temporary disruption to your home and the overall project cost, then balance that against the long-term benefits. An L-shaped extension can transform how you live, giving you more space to cook, relax, and entertain, while also boosting your property’s value. Considering both practical and lifestyle gains will help you decide if a wraparound is the right move for your home.

Some councils use the 50% rule during planning applications (not permitted development builds) to prevent plots from being overdeveloped. Put simply, the rule says you can’t extend your home beyond half of its original footprint. That “original” size is defined as the property as it stood in 1948, or when it was first built (if it was later than 1948). Any extensions added since then also count towards the total.

There’s also a garden element to consider: your extension can’t cover more than 50% of the outdoor space on your plot, either. An architect can help you balance both sets of limits, giving your plans the best chance of approval.

Any building works that impact the neighbouring boundary or existing party wall will require a party wall agreement. That involves you telling your neighbours about it at least two months before you start. If they give written consent to your extension, you won’t need a party wall agreement. But if they don’t reply within 14 days, or they write back in disagreement, you’ll need to get a party wall agreement drawn up. This needs to be done by a party wall surveyor, and the Resi team can help you with finding one.

Adding value is a big reason people choose to extend their homes. Frustratingly, you can’t guarantee how much value you’ll add, with lots of factors coming into play including the market at the time you sell, or where you live.

But for a rough estimate, considering that a wraparound extension often creates a decent amount of extra space, Resi’s data suggests you could add an average of 10% extra value. For a better idea of how much you could increase your property’s worth by, try Resi’s free extension valuation calculator.

Every project is different, so there’s no set timescale for any extension. But a wraparound extension is often a bigger project, so it may take on the upper end of projected timelines. As a rough guide, home extensions in the UK usually take between 7 and 15 months from start to finish. The time is made up of:

• Prep: 2-4 weeks
• Design: 2-5 weeks
• Planning: 8-10 weeks (but can take longer)
• Technical design: 4-8 weeks (building regs and structural engineer)
• Party Wall Agreement: 2-12 weeks (depending on your neighbours, not everyone needs one of these)
• Tender process: 3-6 weeks (hiring a building contractor)
• Building: 2-6 months (depending on how big the job is)