Loft Conversion Cost – How much does a loft conversion cost?

Find out about loft conversion, the benefits, building regulations and stop wondering about how much does a loft conversion cost.

Loft conversions are a popular way to add more space and value to your property. Whether you’re looking to create an extra bedroom, a home office, or a playroom for the kids, a loft conversion comes always handy. However, with so many different types of loft conversions, it can be difficult to know how much you should expect to pay.

In this article, we’ll explore the cost of different types of loft conversions in the UK, from the more affordable Velux conversion to the more complex mansard conversion. We’ll break down the costs involved, including materials, labour, and any additional fees you may need to consider.

Benefits of Loft Conversion

Increase the value of your home.

The increase can be between 15% – 20%, according to the Federation of Master Builders and Nationwide Building Society and market research conducted by the Guardian. According to Nationwide, your property’s value can increase on average by approximately £37,000.

Lower cost, greater value

Loft conversion costs less than a full extension or moving to another property. Once the conversion is built, you can start making money by renting the new space. You do not have to wait to sell the house to see a return on your investment.

Easy to carry out

Converting a loft is quite simple, and it will take only up to two weeks when who will finish it. Not to mention that several loft conversions do not even require planning permission.

Avoid the cost of moving.

Home-movers, according to Telegraph, will have to pay on average, £10,000 to move into a new property (selling your property and buying a new one). By converting your loft, you can avoid unnecessary expenses, stay in the same job, keep the children in the same school and avoid looking for a new parking space.

More natural light

A loft conversion will add more natural light to your property with the right windows. With more natural coming into your house, you will reduce your energy consumption and improve your productivity and overall health.

Many Uses

It´s a very versatile option for your needs; for an extra bedroom or bathroom, for a lounge or additional living area, for an office or a gym or a home cinema. Your imagination is the only limit.

What to consider before a loft conversion?

An extensive and detailed plan will help things run smoothly and keep the loft conversion cost low (as you will have already allocated funds in a preliminary budget and been made aware of any problems that need fixing beforehand). There are several things to consider when planning your loft conversion, including loft stability, type of room, roof pitch, escape roots, energy conservation, and proper ventilation.

  • Loft Stability – if the loft is any higher (from the bottom joists to the top apex) than 2.4m, then you might need the ceilings lowered to ensure structural integrity.
  • Escape Routes – these need to be accessible via an open stairway or large window, or skylight.
  • Energy Conservation – who should install loft conversions with the most up-to-date insulation materials to trap heat in the home during the winter and prevent wasted energy usage.
  • Ventilation – loft conversions also need adequate ventilation to provide clean air to the new room and prevent mould build-up or rising dampness (which can cost considerably more than standard windows and fans to remove!)

How Long Does A Loft Conversion Take?

Loft conversions usually take between 4 to 7 weeks to complete. In the first two weeks, all the work is done outside or within the roof space. On weeks 3 and 4, the floor joists and the loft floor and insulation are completed, while the ventilation and stud walls are still in progress. On weeks 5 and 6, the rest of the house is opened to the loft.

As the staircase is now fully fitted, and the stairway is made good by installing the handrails and bannisters. In the last week, any plastering, and carpentry work is completed, and all the plumbing is installed and tested successfully.

Is My Loft Suitable for Conversion?

Several homeowners consult either an architect or have long meetings with building contractors before they go ahead. However, the most important thing is to consult your local authority about any planning issues. Before you do all of this, consider the following aspects to get an idea if it is possible to convert your loft.

Loft Conversion Assessment

The key features that will determine if your roof space is suitable for a loft conversion are:

  • Head height
  • Pitch
  • Type of structure
  • Obstacle

A roof inspection is necessary by a roofing professional to reveal the roof skeleton and its physical dimensions.

Head Height

  • The usable part of the roof should be greater than 2.2m.
  • Ask the architect or designer you hired to illustrate how much headroom there will be across the floor in the finished space.
  • The standing space is not always clearly conveyed in plans, so many people are disappointed after the conversion has been completed.
  • Habitable rooms have no limitations when it comes to ceiling height.
  • The headroom standard for stairs is 2m, but it can be easily decreased by 100 – 200 MMS on the edge of a stair when necessary.

Water Tank

A sealed hot water system will replace the water tank and plumbing, as there will be no roof space left anymore.

When replacing your boiler with a combi boiler, consider using unvented hot water cylinders instead. They make a far better choice, but they require more space and budget to build a cupboard-sized room.

Pitch Angle

The pitch angle plays great importance when it comes to floor area. The higher the pitch angle, the more loft space there will be, especially if you redesign the roof or use dormers.

Roof Structure

What type of roof do you have? Is it a traditional framed type or a cut rafter and purlin roof?

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Traditional Framed Roof

  • Before the 1960s
    • The rafters and ceiling joists are cut and put together on-site, together with the supporting timbers.
    • Framed roofs are more strong and more stable, so they are more suitable for attic conversions.
    • Another benefit is that you can easily open up space by strengthening the rafters and adding supports.
  • After the 1960s
    • The most popular roof types used were factory-made roof trusses.
    • They use thinner timbers (which are cheaper).
    • Good structural integrity by the use of braced diagonal timbers.
    • House roofs can be erected and felted in a day.
    • Difficult to open up space without additional structural input.
    • The insertion of steel beams is normally required to support the rafter sections and the new floor joists.
    • It is advisable to seek the advice of professional roofers and not attempt to DIY to save money.
    • Consider using laminate or vinyl for the flooring to save money.

Do I Need Planning Permission for a Loft Conversion?

Most loft conversions are considered permitted development and do not require planning permission as long as the building work meets certain conditions, such as not exceeding 40-50 cubic meters and not having dormers or extensions on the front of the house facing the road. You can find more information on the Government’s planning website.

The Party Wall Act and Loft Conversions

If your house shares a wall with a neighbouring property under the Party Wall Act 1996, you need to inform your neighbours in writing that work is taking place; they have the right to contest this if they want to. To make sure your loft conversion goes smoothly, it’s best to talk to your neighbours beforehand.

Loft Conversion Building Regulations

Before you start your loft conversion project, you have to take into consideration any building regulations related to conversions. All home improvement projects in the UK need to comply with the following standards for design, construction, and alterations:

1. Part A – Structural safety: It involves you making sure that the loft wall, floors, and joists are sturdy enough and that there is sufficient headroom in the loft.

2. Part B – Fire safety: It involves making sure that there is an escape route in case of fire and that the right smoke alarms are installed.

3. Part E – Resistance to sound: It involves that you make sure that there is adequate soundproofing in your loft conversion.

4. Part F – Ventilation: It involves that you make sure that there are enough air vents and windows to ventilate the converted space adequately.

5. Part L – Conservation of fuel and power: It involves that you make sure that the converted space is properly insulated to conserve energy.

6. Part P – Electrical safety: It involves that you make sure that a qualified electrician has installed all electrics in your loft.

7. Part GSanitation, hot water safety, and water efficiency: It involves that you make sure that all plumbing has been installed correctly and safely if you plan to install an en suite bathroom as part of your loft conversion.

Is There a Way To Increase The Head Height of My Loft?

It is possible to increase the head height of your loft. This can be achieved by either lowering the ceiling of the room below or raising the roof of the house. Both options require careful planning and construction work, and it is important to consult with a professional builder or architect to determine the most suitable method for your property.

Solution 1: Raise the Roof

A portion or even the entire roof would have to be removed and rebuilt to get the necessary height and structure. Even though this is structurally possible, the cost is high, and it is also difficult to acquire planning permission.

If the whole roof has to be removed, the whole house has to be protected during the construction.

Solution 2: Decrease the Ceiling Height In the Room Below

In several older homes where the ceiling height is 3m or higher, in certain rooms, there is the option of lowering the ceiling to a height of a minimum of 2.4m.

To implement this approach, it is necessary to attach a plate to the wall by using either raw bolts or shield anchors. This plate will serve as support for the newly installed floor joist. It is imperative that the roof structure is firmly connected to the dwarf wall to prevent any potential damage caused by the roof’s expansion.

New Ceiling Joists

The current ceiling joists are probably inadequate to bear a conversion floor. Therefore you will need supplementary joists to meet the Building Regulations. The structural engineer determines the dimensions and grade and will consider the span and the separation distance of the load applied.

Load-bearing walls support the new joists, which are usually elevated just above the current ceiling plasterwork by applying spacers under the end of the joists.

There must be enough space to stop any deflection on the new floor joist from contacting the ceiling plaster underneath. The new joists are laid next to the current joists. Thicker wood is used to bridge the openings over doors and windows to add no stress to the current opening lintel.

Rolled steel joists (RSJ) are usually stipulated for load distribution, and in certain installations, are employed to support the new joist ends. Where head height is restricted, then wider joists, more closely positioned, could be stipulated.

What are the four loft conversions?

The most common ones are dormer conversions, hip-to-gable conversions, roof light conversions, and mansard conversions. Each of these types has its own design and construction requirements, depending on the existing roof structure and the desired outcome.

Room in Roof Loft Conversion

A ‘room in roof’ loft conversion is a type of basic conversion that typically involves the addition of roof lights or skylights to provide natural light. The cost for a basic ‘room in roof’ loft conversion ranges from £15,000 to £17,000 and is probably one of the cheapest solutions and usually involves:

  • Reinforcing the floor
  • A couple of skylights
  • Additional insulation
  • A Loft staircase
  • Heating installation
  • Electrics and lighting
  • Fire doors and smoke alarms

Dormer loft conversion costs

The cost of a dormer loft conversion in the UK can vary depending on several factors. A small dormer loft conversion can typically cost between £2,000 to £7,000, while a medium-sized dormer can be priced at £25,000 to £29,000 for a 20 square metre conversion.

On the other hand, a larger conversion can cost between £30,000 to £60,000. Additional costs may be incurred depending on the specific additions to the conversion, such as plumbing for a bathroom. Labour costs can range from £20-£35 per hour for builders and £35-£45 per hour for plumbers.

Ensuite loft conversion costs

The cost of building an extension in the UK is estimated to be between £1,500 and £2,500 per square metre. Generally, bathrooms are more costly to build and fit than bedrooms and converting a loft to an ensuite bedroom can cost between £2,700 to £4,000 plus VAT per square meter.

Therefore, if you plan to add a double ensuite room as an extension, you can expect to pay between £30,000 and £62,500 for a basic or mid-range extension and between £46,000 to £62,500 for a luxury extension.

The total cost of the ensuite loft extension will depend on the specific requirements of the project, including additional costs such as scaffolding, replacing cast iron soil pipes, installing a window, and adding towel radiators.

What is the cheapest loft conversion?

The cheapest type of loft conversion is the roof light conversion. A roof light conversion can cost around £15,000-£20,000, and It involves installing windows onto the existing roof structure to allow natural light to enter the space.

In general, it’s difficult to determine which lost conversion is the cheapest. Loft conversion costs can vary significantly based on factors such as the size of the space, materials used, and the extent of the conversion work required. However, a basic conversion using a prefabricated staircase and minimal structural work may be more affordable than a full-scale conversion with custom features.

What Loft Insulation Do I Need?

One of the most vital elements to consider when planning and carrying out a loft conversion is how to insulate properly and what type of insulation to use. This can have a major impact on the available space when the conversion is finished. When reconditioning/remodelling an attic or loft space, it is necessary to comply with the local Building Regulations/Standards.

According to the building regulations, the minimum U-value of a roof must be 0.18W/m2 or lower in England. For flat ceilings, the minimum U-value must be 0.16 W/m²·K. In the case of a complete re-roofing, the roof must be insulated to a minimum U-value of 0.15 W/m²·K. The U-value for new roofing constructions is 0.15 W/m²·K, and for refurbishments, 0.18 W/m²·K; these values apply to both flat and pitched roofing structures.

Note: O.18W/m2 equals a 270mm thick layer of fiber or wool insulating material, roughly 175mm of rigid board insulation, or about 125mm of high-efficiency spray foam.

Types of loft insulation available

There are many types of loft insulation available, made from different insulating materials. It is best to get a loft survey done so that a professional installer can advise you on what type of insulation you need and what the cost will be. Loft insulation surveys are often provided free of charge by roof insulation companies.

Here are the main types of roof insulation:

Blanket/Quilt insulation – This type of insulation comes in readymade sheets made of usually artificial materials like glass or rock wool fiber. Mineral wool is the most common type of insulation used in the UK. Blanket insulation is good for large accessible loft spaces as it fits neatly between the joists and is the most common type used in lofts.

Sheet/Board insulation – Ideal for loft conversions and covering the sloping sides of roofs, this type of insulation is easy to disguise by covering with plasterboard, leaving a neat finish. Sheet insulation is usually made from polystyrene material and comes in rigid flat sheets that can be cut to size.

Blown insulation – Normally made from mineral wool and cellulose material, this type of insulation is blown into specific areas of the roof. If you have hard-to-reach spaces in your loft, this is a good option and is quick and easy to install by hiring a professional.

Loose fit insulation – This type of insulation comes in bags and is made of cork granules or recycled newspaper. It simply needs to be scattered in the roof space and is most suitable either as a top-up to existing insulation or in very hard-to-reach places.

How Much Does A Loft Conversion Cost

A loft conversion costs, on average, between £10,000 – £32,000, depending on the property type. However, you could end up paying up to £60,000 for a huge extension. Loft conversion prices are generally affected by the following factors:

  • Your location in the country.
  • The size of the loft.
  • Whether the loft requires any strengthening work.
  • If you are looking to build a roof or dormer windows.
  • Whether you want to have a bathroom.
  • If you need to install central heating.

One of the biggest factors affecting the cost of loft conversion is the location. To illustrate this, below, we have created a table with the average prices for a loft conversion in the UK. The loft conversion prices listed below are estimates only.

Loft Conversion Prices UK

The basic loft conversion cost in the United Kingdom for a 20m² loft starts from £8,700. For a deluxe loft conversion, expect to pay at least £20,000.

For a 30m² basic conversion, the prices start from £9,900. For 30m², of luxury conversion, expect to pay at least £20,600.

Location20m² standard20m² deluxe30m² standard30m² standard
Northern Ireland£8,800£19,600£9,800£20,600
Northern England£11,900£26,600£13,100£27,950
East Anglia£11,400£25,400£12,600£27,000
South East England£12,300£27,400£13,600£28,700
South West England£10,900£24,800£12,400£26,100

Cost of Loft Conversion in London

On average, a loft conversion in London can cost between £45,000 to £90,000, with a basic roof light conversion for 20m2 costing around £15,000 to £25,000

DIY Loft Conversion

The average cost of a DIY loft conversion cost comes to around £30,000, depending on the specifications, materials, and desired size. You can reduce the cost significantly by doing proper research online, asking around, and comparing prices. Track your budget during your project and make necessary changes to your plan, if necessary. And remember, save money for any unexpected expenses!

Certain loft conversions are possible to implement as a DIY project. We recommend hiring a professional loft conversion company for more complicated loft conversions such as mansard, hip-to-gable, or dormer conversions.

When you have a basic loft conversion as a DIY project, you have to make good plans, budget your project carefully, and purchase all the necessary materials before getting started. You need to know how much your loft conversion will cost. You need to allocate enough time to this project phase, but it will save you money.

Here are some basic needs for fittings, materials, appliances, and fixtures you might need to invest in your project. We hope that this list will help you plan your project and estimate the total budget for your project!

Loft Conversion Materials  Breakdown Cost
Structural beams, joists, and masonry: including flooring, doors, and a new staircase£1,500 – £5,000
Electrical wiring and lightning: including plug sockets, bulbs, and fixtures 
Insulation: including plasterboard and boarding£500 – £800
New bathroom: including all pipe work, basins, shower fittings, tiling, and furniture£4,500 – £6,000
Windows: including two small or one large Velux-style skylights, double glazed£800 – £2,000
A new combi-boiler, if necessary£600 – £3,000
Interior design materials: including paint, wallpaper, storage cupboards, and new furniture£800 – £30,000

Note:  if you don`t feel competent and proficient enough to handle the building and construction work, it might be wiser to hire a professional conversion specialist for your project. Don´t underestimate the time and energy that you need to invest in the project.

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Available Grant Types

Loft and attic insulation: In about 25% of homes in the United Kingdom, the heat is lost through the attic. Insulating that space is usually the easiest way of making a big impact. This often results in many lower-paying bills. The minimum depth of the installed insulation in this area is 270mm. Thanks to modern insulation techniques, space remains usable for storage afterwards or even as a living area.

Room in roof insulation: These grants are being offered thanks to the government’s Energy Companies Obligation system. One of the most popular of its kind, the room on the roof basically covers the entire loft with every room—ideal for residents who live in old buildings with inadequate or basically non-existent insulation.

Cavity wall insulation: An even bigger culprit than roofs and attics, external walls are responsible for roughly 35% of all UK heat lost. Loft insulations grant England, Wales, and Scotland, but not Ireland. When the wall has a cavity inside, it loses most of its insulating quality, which usually isn’t that great, to begin with. Who can remedy this by injecting insulating material inside the wall, significantly increasing its insulation capabilities?

Solid wall insulation: It is possible to insulate solid (non-cavity) walls, and it is a much easier process. The thickness of the wall usually tells if it’s solid or not, or if all else fails, the hard hat can assess the bricks themselves in determining if he’s dealing with a cavity wall or a solid wall.

It is possible to apply for more than one grant at the same time. There are no eligibility criteria at the moment, but the government usually prioritizes certain areas of the city.

Who pays for the work?

The energy supplier who awards you the grant. If the process seems to be too complex, don’t worry about it because it is. Luckily the surveyors will help you out. This is their job, and they know what they are doing. It is important to note that these are genuine grants that the energy supplier fully covers, and you won’t have to pay anything unless you asked for something extra that is not covered by the grant.

Attic Conversion Cost

attic conversion cost

The average cost for an attic conversion is £20,000£30,000. A small attic conversion in rural England will cost about £16,000, while for the same job in London, the cost nearly doubles.  The average cost for a small attic conversion is around £27,000.


What is the 4-year rule loft conversion?

The 4-year rule for loft conversion states that if you have converted your loft into a livable space and have used it continuously for at least four years, you do not need to obtain planning permission for the work. However, it is important to note that this rule does not exempt you from building regulations approval, so be sure to check with your local council before undertaking any work.

What is the disadvantage of a loft conversion?

While loft conversions can provide homeowners with valuable additional living space and add value to a property, they do come with some disadvantages. The cost, disruption, impact on the existing structure and potential impact on energy efficiency should all be carefully considered before embarking on a loft conversion project.

What is the minimum height for a loft conversion?

The minimum roof height for a loft conversion typically ranges between 2.2 to 2.4 meters. However, this can vary depending on the type of conversion and the intended use of the space. It’s best to consult with a professional architect or builder for more specific guidance.

Is a loft conversion hot?

The loft conversion space
The loft is always the hottest room in the winter and the coldest in the summer. The warmth of a loft conversion depends on several factors, such as insulation, heating system, and ventilation. Proper insulation and ventilation can help maintain a comfortable temperature, while an efficient heating system can ensure warmth during colder months.

Can I use my loft as a hobby room?

Yes, you can use your loft as a hobby room. Also, as converting your loft into a hobby room is considered permitted development, you do not normally need planning permission.
A hobby room is a great use of that space. Just ensure that the room is safe and comfortable to use.

Where do you put stairs for a loft conversion?

The location of stairs for a loft conversion depends on the layout and structure of the house. Generally, stairs are placed above the existing staircase or in a hallway to minimize the loss of living space. A spiral staircase can also be a space-saving option. It’s important to consult a professional to ensure the safety and functionality of the stairs.

What floor is best for loft conversion?

The best floor for a loft conversion depends on a few factors, such as budget, personal preference, and the intended use of the space. However, the most common types of flooring used in loft conversions are engineered wood, laminate, carpet, and vinyl.

Do I need an architect for a loft conversion?

It is not always necessary to hire an architect for a loft conversion, especially if you are just planning to use the space for basic living or storage purposes. However, if you have a more complex design in mind, like adding a bathroom or changing the roofline, then hiring an architect may be beneficial. They can help you navigate building regulations and create a design that maximizes the space and meets your needs.

What is the most expensive part of a loft conversion?

The most expensive part of a loft conversion is usually the structural work required to reinforce the existing floor and roof, as well as installing a staircase and skylights or windows for natural light. Other costs include insulation, plumbing, electrical wiring, and finishing materials. The cost can vary greatly depending on the size and complexity of the project, as well as the materials and finishes chosen.

What type of loft conversion is the most expensive?

The most expensive type of loft conversion is typically a mansard conversion. This is because the mansard of loft conversion involves a significant amount of structural work to change the shape of the roof and create more headroom. Additionally, mansard conversions usually require planning permission, which can add to the overall expense.

Does a loft conversion replace the roof?

No, a loft conversion usually does not involve replacing the roof. Instead, it involves converting the existing space within the roof into usable living space. However, some structural work may be required to strengthen the roof and ensure it can support the weight of the new space.

Is a loft conversion messy?

Loft conversions can be a bit messy, as some dust and debris may occur during the construction process. However, it’s not necessary to demolish the entire house for a loft conversion. Once the stairs are installed, cleaning is necessary. Overall, a Velux loft conversion should not cause significant damage to the rest of the flat.

Can I put a window in a loft conversion?

Yes, you can put a window in your loft. Adding a window to your loft can significantly increase the amount of natural light that enters the space, making it a more pleasant and inviting environment. Additionally, a window can also provide ventilation and help regulate the temperature in your loft.

Can I convert my loft into a bedroom?

Yes, a loft can be converted into a bedroom. It’s a great way to create more living space in your home without having to move. With a loft conversion, you can transform an unused attic into a comfortable and functional bedroom, adding value to your property while increasing your living space.

Can a Neighbour block a loft conversion?

If the loft conversion is within the permitted development rights, then the neighbour cannot block it. However, if the loft conversion requires planning permission, then the neighbour can object and request the local council to reject the application. The council will consider the neighbour’s objections before making a decision.

What problems can you get in a loft?

Lofts can present several problems, such as poor insulation, limited natural light, and insufficient ventilation. Additionally, low ceilings, awkward layouts, and lack of storage space can also be problematic. Safety concerns related to staircase design and fire escapes may also arise. These issues can be addressed with proper planning and design solutions.

Does a loft conversion need a landing?

Yes, a loft conversion usually requires a landing as it provides a safe and convenient access point to the new room. The landing also ensures compliance with building regulations, which require a safe means of escape in case of fire. Additionally, a landing can enhance the aesthetic appeal and functionality of the new space.

Does a loft conversion need a Vapour barrier?

Yes, a vapour barrier is necessary for a loft conversion. It helps to prevent the buildup of moisture in the roof space, which can cause structural issues and mould growth. A properly installed vapour barrier will also improve the energy efficiency of the loft by preventing heat loss through the roof.

Is scaffolding required for a loft conversion?

Scaffolding is likely to be required for a loft conversion, especially if the work involves structural changes or roof alterations. Scaffolding provides a safe platform for workers, tools, and materials, and ensures that the work can be carried out efficiently and to a high standard. The exact amount of scaffolding required will depend on the size and complexity of the project.