How Much Does a Loft Conversion Cost?

Many homeowners with a significant amount of loft space opt to convert it into a useable living space. To help you answer the question of how much is a loft conversion, this guide sets out the supply, installation, labour and additional costs of a loft conversion.

The average cost of a loft conversion will vary depending on the size and type of your loft. For instance, a 20 square metre dormer loft conversion costs around £25,000 to £29,000, while 30 square metre dormer loft extension is normally priced at £38,000 to £44,000.

For anything larger than 40 square metres, you should expect to pay anywhere from £50,000 to £58,000.

Another common loft conversion is a hip to gable loft conversion which is typically priced £30,000 to £50,000 for a small 20 square metre loft conversion.

If you have space measuring up to 30 square metres, then you should expect to pay around £45,000 to £75,000, while a loft conversion measuring more than 40 square metres can cost as much as £60,000 to £100,000.

One of the most expensive extensions is a mansard loft conversion which starts from £45,000 to £50,000 for a small project, going up to £55,000 to £60,000, while a large mansard loft conversion can cost range from £65,000 to 70,000 or more.

What are the Supply Costs of a Loft Conversion?

If you are looking to reduce the cost of a loft conversion, then you could consider purchasing the supplies from a retailer yourself. There are various loft conversion supply costs including:

Loft Conversion Flooring Cost

One of the most important costs you need to consider is flooring for your loft conversion. Flooring prices vary depending on the material you choose, for example, vinyl flooring costs around £6 to £14 per square metre, while laminate ranges from £7 to £25 per m².

Other popular loft conversion flooring options include hardwood which is normally priced at £35 to £45 per square metre, while you can expect to pay around £5 to £30 per m² for carpet.

Loft Conversion Heating Cost

To ensure your loft conversion is heated properly, you will need to install a new heating system. This may include the price of installing radiators which can be fitted onto the walls of your loft conversion to heat up the space.

You can purchase a typical horizontal or vertical radiator for around £50 to £900, while electrical radiators range from £90 to £400.

If you have room in your budget, you could also consider installing underfloor heating, although this will need to be completed before your flooring is laid. The cost of underfloor heating will vary depending on the type you choose, as there two different options.

Wet underfloor heating which works by pumping water through pipes to heat the floor costs around £60 to £80 per m².

The alternative is dry underfloor heating which is normally priced at £30 to £40 per square metre - features electric mats and wires that are connected to the main electricity supply to heat up the floor.

Loft Conversion Lighting Cost

Loft spaces can usually be quite dark, so it is important that you incorporate as much lighting as possible. This could include ceiling lights which start as low as £7, although can cost up to £4000 if you are looking for a more luxury lighting feature.

Other popular lighting options include lamps that range from £3 to £1000 for table lamps and floors lamps which are normally priced at £12 to £1800.

More advanced lighting options include smart lighting which can be controlled by a smart device, which will help you lower your energy bills and reduce your carbon footprint. You can purchase smart lightbulbs for around £15 to £170.

Loft Conversion Stairs Cost

One of the most important costs you need to consider is a new staircase which will enable you to access your new living space.

The supply cost for a new staircase will vary depending on the type of staircase you choose along with the material.

For instance, a softwood staircase could range from £380 for a straight set of stairs to £800 for z-shape stairs, while a hardwood staircase is slightly more expensive with prices starting from £1400 for single winder staircase with costs rising to £1900 for triple winder steps.

For a more modern design, you may want to opt for a glass staircase, which normally costs around £2500 to £4000. Another unique option is metal steps which are typically priced at £1000 to £3000.

Loft Conversion Windows Cost

The final supply cost to consider is your loft conversion windows which will vary depending on the style you want.

If you are installing a dormer loft conversion, then you will need to consider the cost of dormer windows which are normally priced at £150 for small a window while larger dormers can cost up to £300 per window.

Another popular loft conversion window design is Velux rooflights which are slightly more expensive, as they cost around £320 to £550. They help to create a contemporary and airy living space which will massively improve the aesthetic.

What are the Additional Costs of a Loft Conversion?

There are various other loft conversion costs you need to consider including:

New Boiler Cost

When converting your loft, you may need to hire a heating engineer to check if your existing boiler can be connecting to the new living space. If not, they may advise installing a new boiler, which can be a costly job.

The cost of a new boiler will vary depending on the type of boiler you choose, as some are harder to install than others.

One of the most common boiler installations is a combi boiler which ranges from £1500 to £3500, while a heat-only boiler costs slightly less at £1500 to £2500. You could also look at installing a system boiler which is normally priced at £1500 to £2800.

Underfloor Heating Costs

Loft spaces tend to feel colder in the winter, so underfloor heating installation may be worthwhile to warm up your new living space.

The cost of underfloor heating will vary depending on the system you choose, as there are two different options available.

Wet underfloor heating consists of pipework which is installed under your floor to allow water to pump through and heat your floor. For professional installation, you should expect to pay around £90 to £190 per square metre.

Dry underfloor heating involves installing electric mats or wires which are connected to the main electricity supply in your home. This type of underfloor heating is the more affordable of the two, as it costs around £40 to £80 per m².

Loft Conversion Insulation Cost

Another important cost you need to consider is the price of fitting insulation in your new loft conversion.

The final price will be determined by the type of insulation you choose, for example, sheet insulation costs around £15 to £25 per m², while loose-fill insulation ranges from £5 to £15 per square metre. A more expensive option is blanked insulation which offers a high thickness and is normally priced at £12 to £27 per m².

Tradesmen Costs for a Loft Conversion

The labour cost of a loft conversion is also important to consider, as the job requires a number of tradesmen who will all offer different quotes. To help you get an idea of the cost of loft conversion labour, here is a price breaking for each tradesman.

Joiner Costs

To construct your loft conversion, you will need the help of a joiner who will help to build and fit the frame of your loft conversion, along with installing a new staircase, door frames and more. For a large project such as a loft conversion, you should expect to pay around £160 to £240 per day.

Painter & Decorator Costs

Once your walls are constructed, you should consider hiring a painter and decorator to paint or wallpaper your walls to enhance the aesthetic of your loft conversion.

Painters and decorators tend to charge around £100 to £300 per day to decorate a brand new living space.

Electrician Costs

To ensure any electrical fixtures such as lighting, appliances or electric underfloor heating are installed properly, you will need to hire a qualified electrician. Electricians tend to quote a daily rate of £170 to £340.

Plumber Costs

If you are having a bathroom fitted in your loft conversion, then a plumber will be required to install everything include a toilet, sink, bath or shower. For a job like this, you should expect to pay around £200 to £400 per day.

Kitchen Fitter Costs

Having a kitchen installed within your loft conversion will require the help of an expert kitchen fitter who will install your kitchen cupboards and worktops, while also fitting appliances. A typical kitchen fitter tends to charge about £120 to £200 a day to fit an average-sized kitchen.

Heating Engineer Costs

The daily rate of a heating engineer is around £150 to £500 a day, which will cover everything from installing a new boiler, fitting radiators, and connecting dry underfloor heating.

Plasterer Costs

Before your walls can be decorated, you should hire a plasterer to prepare your walls, as this will help to protect and prime them regardless of whether they are being painted or wallpapered. Plasterers usually quote a daily rate between £150 and £220.

Builder Costs

Hiring a builder is one of the most important things you must do when building a loft conversion, as they will work to create the foundations and the structure of the new living space. An average builder’s daily rate ranges from £130 to £260.

How Long Does It Take to Build a Loft Conversion?

The time spent building your loft conversion is important to consider, as this will also affect the final cost, as the longer the job takes the more expensive it will be. The duration will depend on the type of loft conversion you want and the size of your space.

The below table sets out various durations for different types of loft conversion.

Type of loft conversion Small (20sqm) Medium (30sqm) Large (40sqm)
Dormer 6 to 7 weeks 7 to 8 weeks 8 to 9 weeks
Mansard 8 to 9 weeks 9 to 10 weeks 10 to 11 weeks
Hip to gable 6 to 7 weeks 7 to 8 weeks 8 to 9 weeks
Roof light 4 to 5 weeks 5 to 6 weeks 6 to 7 weeks

Types of Loft Conversion

If you are unsure on which type of loft conversion you want to build, take a look at the following loft conversion price guide which explains the different loft conversions, their costs as well the pros and cons of each.

Dormer Loft Conversion Cost

This type of conversion is normally extended onto an existing vertically-sloping roof. It normally features vertical walls and a horizontal ceiling. The average cost of a dormer loft conversion ranges from £25,000 to £58,000.

The main advantage of a dormer loft conversion is that it provides a significant amount of extra space, so it is ideal for a new bedroom plus an ensuite. This additional space also enables more natural light which will make the room appear larger and more aesthetically-pleasing.

There are also fewer restrictions, as dormer loft conversions usually fall under permitted developments if they meet size regulations.

As a dormer loft conversion involves altering the existing roof it may take a lot longer to construct than other loft conversions. It may also require more structural changes in comparison to a roof light loft conversion.

Mansard Loft Conversion Cost

A mansard loft conversion costs around £45,000 to £70,000. This type of loft conversion is named after Francois Mansard, a French architect who came to prominence in the 17th-century.

The main characteristic of a mansard loft conversion is a flat roof with a 72-degree inward-sloping back wall.

One of the main benefits of a mansard loft conversion is that is a versatile extension which works well for various property types. It can also be designed to match the existing house, allowing it to offer a seamless aesthetic.

A downside of building a mansard attic extension is that you require planning permission before building it, as it involves a significant amount of changes to the roof and building structure. It is also one of the most expensive loft conversions and can take up to 11 weeks to complete.

Hip to Gable Loft Conversion Cost

Hip to gable loft conversions involves transitioning a sloping hipped roof to a flat gable end. The price of this type of conversion ranges from £30,000 to £100,000.

The main advantage of a hip to gable loft conversion is that it enhances the roof space massively, as hipped roofs tend to have limited space. This will help to accommodate a staircase along with a living space that increases the value of your home.

This type of loft conversion will require you to apply for planning permission as it is classed as a major roof alteration. It can also be very expensive if you have a large roof space.

Roof Light Loft Conversion Cost

A roof light loft conversion is one of the most basic extensions, as it does not involve changes to the roof, and instead just alters the inside of the attic. This is a fairly cheap loft conversion which is normally priced at £23,000 to £54,000.

The main reason many homeowners opt for a roof light loft conversion is that it is the most affordable option that only takes around 4 to 6 weeks to complete.

It is also ideal for people who live in a conservation area, as most of the time you do not need planning permission.

There are some restrictions with this type of conversion, as the roof is not expanded so unlike other loft conversions, you won’t benefit from extra living space.

How Much Does It Cost to Remove a Loft Conversion?

If there is an issue with your loft conversion, you may need to get it removed. The best and simplest way to do this is by ripping out the staircase and replacing it with a standard loft hatch which will cost around £500 to £1000.

You may also need to consider waste removal costs which can amount to around £70 to £180 a day for a professional company to get rid of your unwanted items.


Q: What is a loft conversion?

A: A loft conversion involves transforming attic space into a useable room which can be accessed via a staircase rather than a loft hatch. This may simply include changing the interior or some structural changes may need to be made to increase the head space in the attic.

Q: How much value does a loft conversion add?

A: Loft conversions can add around 15 to 20 per cent to the overall value of your property, although this will vary depending on the type of loft conversion you choose.

Q: Do you need planning permission for a loft conversion?

A: Dormer and roof light loft conversions do not normally require planning permission as long as they follow the current guidelines. However, if you plan to extend or alter the roof significantly, then you will need to submit an application.

There are certain restrictions in place that you must follow, for instance, you must obtain permission if you extend the roof more than 40 cubic metres for a terraced property or 50 cubic metres for semi-detached or detached homes.

The roof extension also must not exceed the existing roof slope and must be no higher. You can also not install a balcony or veranda without getting permission first.

Q: Is a loft conversion cheaper than an extension?

A: Many homeowners opt to build a loft conversion rather than a full house extension as it is more affordable and takes a lot less time to build. Loft conversions range from £23,000 to £100,000 while an extension can cost up to £200,000.

Q: Where do loft conversion stairs go?

A: When building a loft conversion it is important that a fixed staircase is installed to allow easy access to your new living space. The new steps can be attached to the existing staircase to create a more seamless design. If this is not an option, then stairs can be installed in another room where there is more space.

You can also opt for a space saving staircase which should be installed next to the loft conversion opening, although these are only used as a last resort, and usually in properties with very limited space.


Author: Heather B

I am a seasoned copywriter from Liverpool - who after graduating with a BA (Hons) degree in English Media and Cultural Studies - went on to specialise in the creation of business and lifestyle copy for a wide range of industries across the UK and USA.