On average you should have roughly £50-70,000 for a typical single storey rear extension. A good estimate for your extension cost is to multiply the square meter area of the proposed extension by £2,500. Therefore, if you have an extension which is 5x4m – 20 square meters your extension would roughly cost £50,000. You should also factor in any potential VAT which would add a further 20% to the costs. This estimate doesn’t include the internal works if you were fitting a new kitchen, say. Depending on your specification, it could be £3000 per square meter if you are having a high-quality specification and finish.

In some instances, house extensions may be constructed under permitted development rights, eliminating the need for planning permission. Nevertheless, it is crucial to engage with your local planning authority or home extension experts to confirm adherence to regulations.

The project cost of a double storey extension per square metre is only slightly higher than single storey home extension and you can save a lot of money by extending a double storey at same time as a single storey extension, rather than doing your home extension as two separate projects. ​ The cost of double storey home extension will usually average around £1800 per sqm. The cost of your project will vary depending on the type of home extension design, materials and level of finishes you choose. As a rough guide, we average that a standard 4m x 5m double storey extension ( with a total of 40sqm gained over the two floors) will cost you around £72,000 for the build cost alone. ​ To give you an idea of the architects planning and professional fees you will need to take into consideration, these can be summarised as follows: Architects planning application drawings in London £1,150 Building Regulations Drawings in London £850 Planning application fees for a two storey extension is £528. Building control charges depend on the size of your extension’s. Average £900

Adding a double storey extension to your home will certainly boost the value of your home on the property market. Research carried out by Nationwide Building Society shows how home improvements such as home extensions can add significant value to your property. Adding a double bedroom with an en-suite to your home can increase the value by upto 23%.​

If you are planning on a double storey extension, such as a double storey side extension, to add value and space to your home, you might be able to build your home extension under permitted development. However, there are some restrictions to what you can build under permitted development. You can build a two storey home extension to the rear of your property, the tallest point of your home extension cannot be taller than the highest point of the existing roof of your home or extend beyond the rear wall for more than 3m. In addition, the materials of your new home extension must to match the material finishes of the existing building and it needs to be at least 7m from the boundary. The side of your extension will need to be non-opening and obscure-glazed. ​ Last but not least, if the roof of your new extension connects to the existing roof you will have to subtract the volume of the extension roof from any loft conversion london volume allowance you might have.

It depends. Many extensions fall under Permitted Development Rights (PDR), especially for rear or side extensions within specific size and height limits. However, if your property is in a Conservation Area, is listed, or exceeds certain thresholds, you’ll likely need full planning permission.

The most popular types include: Rear extensions (single or double-storey) Side-return extensions Wrap-around extensions Loft conversions Basement excavations (in select areas) Each comes with different planning and structural considerations.

On average: Design & Planning: 1 month Planning Approval: 8–10 weeks (if required) Building Regulations Drawings & Tendering: 1–2 months Construction: 3–6 months, depending on complexity We provide detailed timelines at the outset of each project.

Costs vary greatly depending on size, complexity, and finish. As a general guide: Basic extensions: £2,500–£3,000+ per m² High-spec finishes or complex builds: £3,500–£4,500+ per m² We always recommend setting aside a 10–15% contingency.

Absolutely. At Excela, we manage all aspects of the planning process on your behalf, including: Pre-application advice Full planning submissions Liaison with local authorities Appeals (if necessary)

Neighbour objections can influence planning outcomes but don't automatically block approval. We advise early communication and design strategies that minimise impact (e.g. daylight/sunlight studies, step-backs). We also offer Party Wall advice if needed.

Yes. We provide a fully integrated service from initial concept through to completion. This includes: Concept design Planning and technical drawings Tendering and contractor selection Project and construction management