Loft Conversion

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 conversion cost

As the need for more space increases, instead of moving to a new property, a loft conversion is one of the most straightforward ways of extending your property.

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.

How To Plan For 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 the following:

    • 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 mold 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 banisters. In the last week, any plastering, 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 on plans, so many people are disappointed after the conversion has been completed.
    • Habitable rooms have no limitation 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 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?

Loft conversions do not usually require planning permission as they tend to be considered Permitted Developments (PD). However, If you are changing the property’s footprint (extending or changing the roof space), your design will need to comply with certain rules and regulations. In this case, you will need to apply for planning permission. You can find more information on the Government’s planning website.

The Party Wall Act and Loft Conversions

In addition to planning permission, if your house shares a wall with a neighboring property under the Party Wall Act 1996, you need to inform your neighbors 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 neighbors beforehand.

Loft Conversion Building Regulations

Before you start your loft conversion project, you have to take into consideration any building regulations related to conversions, as 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 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?

Did the initial inspection of the roof space show that the head height was under 2.2m? If so, you have two options, both costly, and you will need help from a professional.

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 some rooms, there is the option of lowering the ceiling to a height to a minimum of 2.4m.

This method requires a plate to be bolted to the wall with raw bolts or shield anchors, from which who will hang the new floor joist. Proper bonding between the roof structure and the dwarf wall is needed to stop the roof from spreading.

Any DIY participation should be confined to demolition supervision and cleaning.

New Ceiling Joists

The current ceiling joists are probably inadequate to bear a conversion floor. Therefore who would need supplementary joists to meet the Building Regulations? The structural engineer determines the dimensions and grade, who 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.

Room in Roof Loft Conversion

The cost for a basic ‘room in roof’ loft conversion starts from £15,000 and is probably one of the cheapest solutions. This 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 Extension

Dormer loft extensions are another option that does not require making big changes to the roofing structure. This structural extension projects vertically from the plane of the sloping roof. With the addition of dormer windows, the usable floor space increases and transforms the attic into a naturally bathed space. Who can use the additional floor space to add more head height, giving more flexibility when placing the stairs.

The average dormer loft extension cost comes to £20,000+. However, the average cost of a double ensuite room is between £35,000–£45,000.

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/remodeling 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 ranges from £8,750 to £10,850. For a deluxe loft conversion, expect to pay from £19,950 to £24,800. For a 30m² basic conversion, the price comes between £9,750 – £12,350. For 30m², expect to pay from £20,550 to £26,050.

Location 20m² standard 20m² deluxe 30m² standard 30m² standard
Northern Ireland £8,750 £19,550 £9,750 £20,550
Scotland £12,250 £27,350 £13,650 £28,650
Wales £10,850 £24,250 £12,050 £25,450
Northern England £11,850 £26,550 £13,050 £27,900
Midlands £11,100 £24,600 £12,250 £26,000
Yorkshire £11,890 £26,600 £13,120 £28,000
East Anglia £11,350 £25,300 £12,550 £27,000
South East England £12,250 £27,350 £13,600 £28,700
South West England £10,850 £24,800 £12,350 £26,050

Cost of Loft Conversion in London

The loft conversion cost in London starts from £12,700 for 20m² for a standard loft conversion and £28,200 for a deluxe loft conversion.  The prices are slightly higher in inner London due to increased labor and material prices in the city, so expect to pay £1,000- 1,200 pounds more.

20m²  standard 20m² deluxe 30m² standard 30m² deluxe
Inner London £13,400 £30,000 £15,000 £31,500
Outer London £12,700 £28,200 £14,100 £29,600

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 afterward 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 grants England, Wales, and Scotland, but not Ireland. When the wall has a cavity inside them, 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

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.

attic conversion cost

Attic conversion costs vary depending on your requirements and in which part of the UK you live. For instance, a shell conversion will cost less than a full mansard job with bathroom fittings and new plumbing.

Attic Conversion Prices

 Attic conversion type   Cost
An average attic conversion £20,000 – £30,000
A shell conversion £16,000
A small Velux conversion without plumbing £20,000

Bungalow Loft Conversion

Bungalow loft conversion cost is  30%-40% cheaper than house conversion. It depends a lot on the size of your project and for what kind of purposes you are planning the loft conversion. Typically a bungalow loft conversions are used for extra bedrooms. This kind of project is quite simple and inexpensive to implement. The cost, however, increases if there is not enough space for a staircase to be safe enough.

Hip to Gable Loft Conversion

The average cost of a hip to gable loft conversion will be around £33,000. However, depending on your requirements, your location, and the quality of the materials, the cost can reach £38,000. 

When to use

If your house has a hipped roof with sloping sides, then a standard loft conversion is not the best solution for you, as a hipped roof is usually difficult to convert. With hipped roofs, i) there is not much space, ii) there is little headroom under the diagonally sloping ceilings, iii) and they cannot support the beams and joists, as required in traditional conversions.

Benefits of Hip-to-gable Loft Conversion

This is where a hip-to-gable loft conversion comes in, as you can maintain your home’s structural and aesthetic integrity and create this extra space you need. This type of loft conversion extends your house on the sloping side, and a vertical wall is built to replace the sloping roof at the end with the same height at the ridge, filling in space in between.

The newly created space can fulfill any function you need most and can make your life easier. Popular choices are usually a master bedroom with an ensuite, a second living room, and an office or a gym space. You can even accommodate a fully integrated staircase with a hip-to-gable loft conversion.

Planning Advice

You need to remember before you start planning your hip-to-gable loft conversion that the height of the space needs to be at least 2.2 meters. Estimate carefully how much money you need to spend and try to involve a conversion specialist right from the beginning to help you do the planning. It might cost you more, but this type of loft conversion is a little bit more challenging and expensive than the standard loft conversion.

Hip-to-gable Loft Conversion Prices

To help you estimate the hip-to-gable loft conversion cost, with did some research and gathered estimates from several loft conversion companies in the UK.

Loft conversion company Cost £30,000 – £35,000 £32,000 £35,000

Mansard Loft Conversion

The mansard loft conversion is named after the 17th Century French architect Francois Mansard. It is usually created at the rear side of the property, extending across the entire plan. This type of conversion has a flat roof with the back sloping inwards at 72 degrees. The windows are usually built into small dormers. The average Mansard loft conversion cost is about  £45,000-£55,500.


With proper planning and design specifications, you will get the extra space you always desired while maintaining the property’s structural integrity. This is what a Mansard loft conversion is suitable for!

When To Use

Mansard loft conversions are suitable for detached and semi-detached houses and terraced properties, chalets, and bungalows. This makes the mansard loft conversion a prevalent method among loft conversions.

Mansard Loft Conversion Prices

We contacted several loft conversion specialists and companies. We requested information about the average mansard loft conversion cost to help you get a better idea of how much is a mansard loft conversion.

Loft Conversion Company   Cost £35,000 £33,000 – £34,000 £34,000 – £45,000

How To Find A Good Loft Conversion Company

When you are starting to plan your loft conversion project, and you are unsure how much a loft conversion costs or whether you need to apply for planning permission for your loft conversion, consult your local council, a loft conversion company, or an architect. On top of that, you can also apply online to receive free loft conversion quotes from our nationwide database of tradespeople and also try other networks such as RatedPeople, MyBuilder, Checkatrade, etc.

Here are several tips to help you find a qualified conversion specialist or company

    • Stay local, choosing the company.
    • Ask your insurance company for recommendations.
    • Check credentials.
    • Check the contractor`s license and insurance.
    • Get it in writing.
    • Don`t pay for labor upfront.
    • Ask for copies of receipts.


Aloft conversion project is a relatively easy way to increase the space and value of your property. It does not require a very long time to complete, and the ROI is also great. When the project is completed, you will have plenty of new space to use as an extra bedroom, an additional living room, a playroom or an additional bathroom, etc.

You can attempt to DIY to reduce the loft conversion cost, but if you do not feel confident or lack the skills, it is better to hire a contractor for your project….. But remember! Consult always with a conversion specialist in any case. We wish you good luck and enjoy your extra space!

Frequently asked questions

Is a survey necessary to obtain a loft insulation grant?

Yes, regardless of what type of wall, flat, or roof we’re talking about, a survey is mandatory. It is, however, a free loft insulation survey. A third party pays government loft insulation grants, but more about this later.

Can flat residents apply for loft insulation grants?

In most circumstances, yes. If you live in a detached house or an apartment complex, there is a very high probability that you will need permission from the landlord before applying for the grant.

Insulation grants for tenants 

Once again, until you have the landlord’s permission, you will not be able to apply for a grant. There are some exceptions, like tenants of the housing association and council properties. They can apply for grants, too but through different methods.

What about extra costs?

Loft insulation grants are usually free of charge, but special circumstances warrant extra costs. For example, if there is dampness, that will likely not be covered by the grant and require separate funds from the applicant(s).

How long does it take to apply for a grant?

The work usually takes about a week, but the whole process can be over within two weeks from the moment the application went through.


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