How Much Does a Loft Conversion Cost?

Many homeowners with spare loft space opt to convert it into a useable living space.

But how much does it cost to get a loft conversion in 2021?

In this guide, we cover all the costs you need to know about - from what you can expect to pay for materials and installation to the additional loft conversion costs you might incur along the way.

Let's get straight to it.

Although the average cost of a loft conversion will vary depending on the size of your loft and the type you choose, here's what you should expect.

A 20 square metre dormer loft conversion costs around £25,000 to £29,000, while a 30 square metre dormer loft extension is normally priced between £38,000 and £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. Prices for this start 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 range in cost from £65,000 to £70,000 or more.

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What are the Supply Costs of a Loft Conversion?

Want to save a bit of money while getting your loft converted?

You could consider purchasing the supplies from a retailer yourself.

In the following subsections, we cover the various loft conversion supply costs you should expect.

Loft Conversion Flooring Cost

One of the most important costs you need to consider is flooring for your loft conversion.

Question is: how much does loft conversion flooring cost?

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. And if you want carpet for your loft conversion, you should expect to pay around £5 to £30 per m².

Loft Conversion Heating Cost

To ensure your loft conversion is heated properly, you will need to install a new heating system in it.

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 anywhere between £50 to £900, while electrical radiators range from £90 to £400.

An alternative option is to install underfloor heating.

But there's a catch.

The cost of underfloor heating is higher and it would need to be completed before your flooring could be laid.


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

The second option is dry underfloor heating which costs around £30 to £40 per square metre. This 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 be quite dark.

This means that it's critical that you incorporate as much lighting as possible.

This could include ceiling lights. These start as low as £7 but can cost up to £4000 if you are looking for something more luxurious.

Other popular lighting options include lamps. These range from £3 to £1000 for table lamps, while floors lamps are normally priced from £12 to £1800.

More advanced lighting options include smart lighting. These can be controlled by a smart device (like your smartphone) and will help you to 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 once it's been created!

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-shaped stairs.
  • A hardwood staircase is slightly more expensive, with prices starting from £1400 for single winder staircase and rising to £1900 for triple winder steps.
  • For a more modern design, you may want to opt for a glass staircase. On average, glass staircases cost between £2500 to £4000.
  • Another unique option is metal steps, which are typically priced around £1000 to £3000.

Loft Conversion Windows Cost

There's one final thing to consider:

Getting loft conversion windows installed.

The cost of loft conversion windows 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. These 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. These are slightly more expensive, as they cost around £320 to £550. They help to create a contemporary and airy living space and will greatly improve the aesthetic.

What are the Additional Costs of a Loft Conversion?

What other lost conversion costs do you need to know about?

Here are a few.

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.

Here's the deal.

This can be 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 Cost

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

As we've already touched on, the cost of underfloor heating will vary depending on the system you choose.


Your first option is wet underfloor heating.

This consists of pipework which is installed under your floor, which allows water to be pumped through. For professional installation, you should expect to pay around £90 to £190 per square metre.

Your second option is dry underfloor heating.

This 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.
  • Loose-fill insulation ranges from £5 to £15 per square metre.
  • A more expensive option is blanket insulation which offers a high thickness and is normally priced at £12 to £27 per m².

Tradesmen Costs for a Loft Conversion

Here's the thing.

The labour cost of a loft conversion is critical to consider, as the job requires various tradesmen - each of which will provide different quotes.

To help you get an idea of the cost of loft conversion labour, here are the prices you should expect for each type of tradesman.


Joiner Costs

To construct your loft conversion, you will need the help of a joiner. They 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

You will need to hire a qualified electrician to ensure any electrical fixtures (such as lighting, appliances, or electric underfloor heating) are installed properly.

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 - including a toilet, sink, bath, or shower.

For things like this, you should expect to pay a plumber 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. They will install your kitchen cupboards, worktops, and appliances.

A typical kitchen fitter charges about £120 to £200 a day to fit an average-sized kitchen.

Heating Engineer Costs

A heating engineer will install a new boiler, fit radiators, and connect dry underfloor heating.

The daily rate of a heating engineer is around £150 to £500 a day.

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 significantly affect the final cost. The longer the job takes, the more expensive it will be.

The time it takes 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

Have you thought about the type of loft conversion that you'd like to have?

In this section, we cover what styles of loft conversion you could have, how much they'll cost you, as well as the pros and cons of each.

Dormer Loft Conversion Cost

A dormer loft conversion is normally extended onto an existing vertically-sloping roof. It usually features vertical walls and a horizontal ceiling.

The average cost of a dormer loft conversion ranges from £25,000 to £58,000.


What are the upsides of a dormer loft conversion?

One advantage is that it provides a significant amount of extra space. This makes it ideal for a new bedroom plus an ensuite. The additional space also enables more natural light to come in - which will make the room appear larger and more aesthetically pleasing.

And it get's better.

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

That said:

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

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

A mansard loft conversion costs around £45,000 to £70,000.

One upside of a mansard loft conversion is that it's a versatile extension which works well for various property types. It can also be designed to match the existing house.

But the downside?

Building a mansard attic extension requires 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 involve transitioning a sloping hipped roof to a flat gable end.

The price of a hip to gable loft 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 both a staircase and a living space and will also increase the value of your home.

However:

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. Instead, it just requires alterations to the inside of the attic.

On average, a roof light loft conversion costs between £23,000 to £54,000. Compared to alternatives, this is a fairly cheap loft conversion.


And this is why many homeowners opt for a roof light loft conversion - it's simply one of the most affordable options which only takes around 4 to 6 weeks to complete.

It is also ideal for people who live in a conservation area, as these do not usually require planning permission.

There are some restrictions with this type of conversion though; because the roof is not expanded, you won’t benefit from extra living space like you would with other types of loft conversions.

How Much Does It Cost to Remove a Loft Conversion?

Here's something to consider:

If there is an issue with your loft conversion, you may need to get it removed.

The best and simplest way to remove a loft conversion is to rip out the staircase and replace it with a standard loft hatch. This would cost around £500 to £1000.

You may also need to consider waste removal costs. This would cost £70 to £180 a day for a professional company to get rid of any unwanted items.

FAQs

Q: What is a loft conversion?

A: A loft conversion involves transforming attic space into a useable living areas which can be accessed via a staircase - rather than a loft hatch. This may simply require changing the interior, but some structural changes may need to be made to increase the head space in the attic before it can be converted.

Q: How much value does a loft conversion add to your property?

A: Loft conversions can add around 15 to 20 per cent to the overall value of your property. However, 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 must also 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 usually only used as a last resort in properties with very limited space.

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Sources

  1. https://www.realhomes.com/advice/an-essential-guide-to-loft-conversions
  2. https://www.jonpritchard.co.uk/heating-your-loft-conversion/
  3. https://jsbuilders.co.uk/what-is-the-cost-of-fitting-a-new-staircase/
  4. https://www.nklofts.co.uk/news/where-should-the-staircase-go-for-my-loft-conversion/
  5. https://www.planningportal.co.uk/info/200130/common_projects/36/loft_conversion
  6. https://www.a9architecture.co.uk/blog/2019/2/11/how-much-does-it-cost-to-convert-a-loft
  7. https://loftconversions.wales/hip-to-gable-loft-conversion/
  8. https://abbeylofts.net/blog/mansard-loft-conversions/
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.