Loft conversion costs 2022 and how to budget for the perfect design

This is the lowdown on loft conversion costs and how to make this home reno project worth your while

Interior of dormer loft conversion
(Image credit: Simply Loft)

Loft conversion costs could make staying put and creating more space in your existing home a sensible option compared to the bill – and disruption – that comes with moving to a larger home.

A simple loft conversion could start from as little as £20,000 and is a tempting house improvement project, allowing you to create an extra bedroom, additional living space or a home office, among other options.

But, of course, loft conversion costs will depend on your loft conversion plans, the type of design you opt for, which rooms you create on this floor of your home, and whether you can make use of your permitted development rights or need to apply for planning permission.

Our guide has everything you need to add up the costs of this type of house renovation.

How much will a loft conversion cost in 2022?

Loft conversion costs will vary depending on size, whether you'll need to alter its structure for staircase access, the type of conversion you're going for and where you live in the country. But, on average, loft conversions range anywhere between around £20,000 and £67,000, according to Andy Simms, construction consultant at MyBuilder (opens in new tab).

To break loft conversion cost down further, identify the type you are going for. MyBuilder provides the following guidelines for the different types:

A basic, room in the roof conversion: for the simplest of loft conversions, usually involving floor reinforcement, skylight(s), insulation, a staircase, electrics, lighting and heating plus fire safety measures, loft conversion prices can start from around £17,250 to £23,000

A dormer loft extension: including all the provisions above, plus a dormer window. Loft conversions with dormers might be your next best option if the basic rooflight conversion doesn't offer enough head height or floor space. Expect to pay from £36,000 to £67,000 with an average of around £52,000.

A mansard extension: expect to pay from £52,000 to £81,000 with an average of £67,000.

A hip-to-gable extension: expect to pay from around £48,000 to £75,000 with an average of £62,000.

Ready-made loft conversions, made off-site and craned into position are quick and will reduce labour costs, which can be beneficial if you live in an area where labour costs are higher. Expect to pay around £63,000.

A conversion that requires change of roof structure: this is obviously the most costly of options, since removing and rebuilding the roof will require an experienced designer and increase labour and material costs. This type of conversion is likely to cost upwards of £40,000.

Do loft conversions add value?

Loft conversions provide one of the best returns on investment you can get when it comes to extending, with experts suggesting they add up to 20% to your home (more on this below). To make it worth it, the loft conversion cost shouldn't be greater than the added value to your property, so do the maths and be sure to check out the ceiling price for properties in your area to avoid disappointment before you start.

Get an individual estimate for your loft conversion with the help of our extension cost calculator.

bed in a converted chapel with storage built around it

(Image credit: Chris Humphreys)

Additional loft conversion costs: planning and professional fees

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Loft extensions can usually be completed under permitted development rights, but it is worth obtaining a certificate of lawfulness (£103) from your local council for the work and checking whether you will need planning permission for a loft conversion.

Should planning be required, expect planning permission fees (£206); these may be included in your agreed contract with the loft company, but do check. 

If you live in an attached house, you will need a party wall agreement with your neighbour(s). A typical average cost is around £1,000.

Building control fees (around £500, plus VAT) are also payable by the homeowner to the local authority or a government-approved, independent inspection company, to check that the work is as contracted and to issue building regulation certificates to prove that it has been carried out in accordance.

You’ll find small companies will usually charge 10 to 15 per cent less than large companies.

Home office storage with blue cupboards and open shelves

(Image credit: Neville Johnson)

Additional loft conversion costs: design and other fees

It's likely that design fees are included within your loft company's quote, but you may wish to appoint an architect to design your loft conversion. 

‘Architect fees are likely to start from £2,000 plus VAT for design and planning advice up to and including your application, and could easily be as high as £10,000 plus VAT or more for a full mansard,’ says Mark Morris, planning consultant and communications manager at Urbanist Architecture (opens in new tab).

‘Architect fees for technical design and building regulations approval are likely to start from £5,000 plus VAT.’

If you need a structural engineer? ‘Initial advice: from £150; for technical design/building regulations approval, from £800,’ says Mark.

‘You could also need: a measured building survey (from £800); a daylight/sunlight survey (if you need to make sure your loft isn’t going to cut off light from your neighbours),’ he adds.

There could be other loft conversion costs to factor in. ‘If you live in a house built before 1914 or live next to woodland, there’s a good chance you’ll need a bat survey before any work can start,’ says Thomas Goodman, property and construction expert at MyJobQuote (opens in new tab). ‘Plus, if your home hasn’t had any work carried out on it for some time, there may be general repairs needed such as retiling and repointing to make your loft space dry and warm.’

If you have asked your architect to put the contract out to tender, appoint the builder and administer the contract, budget for a further three to seven per cent of the build cost. Or, you can agree a day or hourly rate for ad hoc site attendance.

The interior fittings of your loft extension will usually include the basics: sanitaryware; electric points and basic light fittings; door and window furniture; skirting and woodwork; possibly flooring. The price may also include basic decoration – often an all-over spray paint with a white finish for walls and woodwork. For anything extra, you will need to ask for quotes on top of the original price.

The cost of loft conversion vs what you should spend

Given that loft extension cost is often upwards of £36,000 (but often much more, particularly in large cities and in larger properties), there is a limit to how much you should spend on your loft conversion. 

As aforementioned, if you plan on eventually selling the house, you will need to consider the ceiling price of your street – an estate agent can advise on this. Essentially, you want the value of your house to increase by at least the cost of your entire loft conversion, but by spending too much, you may over-value your own house, making it difficult to sell for an appropriate profit.

Comparing the quoted cost of your loft conversion, plus the value of your home, with the cost of moving to a larger house in the same area is a worthwhile practice in assessing the benefits of converting the space.

For example:

Your house is valued at £270,000.

The loft conversion costs £50,000, making the projected cost of the home £320,000.

However, the ceiling price of your street is £300,000, making it impossible to recoup the £20,000 excess spent on a loft conversion.

If there is a house in your area with the space you require for less than £320,000, it is worth considering a move, rather than investing in the loft conversion.

Lucy is Global Editor-in-Chief of Homes & Gardens having worked on numerous interiors and property titles. She was founding Editor of Channel 4’s 4Homes magazine, was Associate Editor at Ideal Home, before becoming Editor-in-Chief of Realhomes.com in 2018 then moving to Homes & Gardens in 2021. She has also written for Huffington Post, AOL, UKTV, MSN, House Beautiful, Good Homes, and many women’s titles. Find her writing about everything from buying and selling property, self build, DIY, design and consumer issues to gardening.

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