Loft Conversion: 2024 Full Guide

Loft Conversion: 2024 Full Guide

Matthew Montague
9 minutes


Loft conversions are a great way to increase the living space in your home, in what is usually the least destructive way. The loft is often an unused space, and can be converted into an extremely flexible space - do you require a new master bed and bath, a good-sized guest bedroom, office space, or a playroom for teenagers to escape to? The loft conversion can sometimes be a favourable alternative to extending, as the space is already there. However, the usability of that space depends on the original construction of the house. Throughout this article, we take you through whether or not your home is equipped for a loft conversion, the different kinds of conversions that you can achieve, and the critical elements that need to be considered, finishing with our key-step summary and top tips!

Table of contents

Are you able to Facilitate a Loft Conversion? 

When considering whether or not your property can facilitate a loft conversion you need to consider 4 elements: 

  1. Your roof structure 
  2. The head height available 
  3. The pitch of your roof
  4. Any other obstacles 

Your Roof Structure:

Let’s start by considering the structure of your roof. Typically there are two different types of pitched roof. The first type is a traditional cut roof, which tends to be on all pre 1930’s homes. This means that the rafters (sloping beams inside your loft to support the roof) are in a typical roof shape, which is therefore much easier to convert and allows for lots of room. 

The other typical roof structure is a trussed roof which is where the supports are in a ‘W’ shape, running across the main cross-section of the roof. Both roof structures can be renovated into a liveable space, however the trussed roof tends to be more difficult, time-consuming and expensive. In both cases, and in particular with a trussed roof, it is crucial to take on the advice of a professional early on. 

Head Height: 

Although there is not a specific rule from building regulations about the roof height for your loft conversion, the general rule of thumb is that you need a minimum of 2.5 meters (250cm). This height allows you a minimal room height, 2.2m (220cm) plus some depth for floor and ceiling strengthening and the inclusion of insulation. In order to measure this correctly, you need to take the measurement from the top of the floor joist in the loft to the underside of the ridge beam in the centre of the room. 

The Pitch of the Roof: 

When it comes to the pitch of your roof, it is very simple - the steeper your roof, the better it is for a loft conversion. The steeper the pitch of your roof, the more head height you will achieve and the more space you will achieve. For a successful conversion, you really need an angle with a minimum of 30 degrees. 


Obstacles you might encounter are typically water tanks, pipework, roof structure, chimneys and sometimes even boilers. When it comes to water tanks, you will probably need to consider a different system for your home as part of this project. This is might result in a smaller tank that needs to be stored within the house, or maybe a combined heating system which eliminates the need for storage tanks, you will need to consider the cost of a new system, and also the cupboard space within the original layout that can allow for this. 

As for your chimney, ideally the chimney can be worked into the scheme - but sometimes these are redundant and can be simply removed, using an architect here will  prove valuable as they are likely to be able to create the best spatial design, considering the position of the chimney, stairs etc. 

Consult with an architect about your home here.

Image by Brotherton Lock c/o Inglis Badrashi Loddo Architects

Different Kinds of Loft Conversions 

There are 4 typical types of loft conversions: 

  1. Roof Light Loft Conversion 
  2. Dormer Loft Conversion 
  3. Hip to Gable 
  4. Mansard Roof Conversion 

Roof Light Loft Conversion 

This kind of conversion is generally the cheapest and easiest way to convert a loft space. Roof light conversions are where you open up the structure that is already there (if possible) with the addition of roof lights, stairs, floor reinforcements and insulation.

This type of conversion is relatively simple to achieve, with minimal disruption to your home. You are utilising the original space, reduced in size however the space now has daylight and ventilation. This can be a great option if you’re looking for an extra children’s bedroom, study/office or small playroom. 

Dormer Loft Conversion 

A dormer loft conversion is the box shaped addition to the roof structure which is  added to a pitched roof. They are designed to project out horizontally and generally include a standard window on the end to let light into your new space and enable views from within.

These are a very popular option as they are a little more complicated and disruptive, but they do add valuable space to the scheme, are still cost effective and can be designed to fall within permitted development rights (meaning the project does not require planning permission) if they are at the back of the property. The only downside is that they are not always as aesthetically pleasing as some of the other options. 

Hip To Gable

A hip to gable conversion is where the hip (slanted roof) usually on the side of the property is extended out to become a vertical wall, creating a new gable end. This option is a very popular choice for bungalows or semi detached houses. It is slightly more expensive and difficult than the options above, however in return you are quite often able to achieve a much larger space. The issue is that this type alteration will affect the view of the house from the street and therefore may not gain planning permission.  

Image by Matt Clayton c/o Cox Architects

Mansard Roof

Mansard roofs are really roof replacement with a structure that looks as if a whole new floor has been added to a property, found most typically on a period property or a terraced house, and in urban locations. Mansard roofs create the largest space of all the conversions, with the walls at an angle of 70 degrees and higher, they are almost vertical.

This type of conversion is the most expensive, takes the longest and will definitely require planning permission, however, it can also mean adding an entire floor to your home with workable rooms that don’t feel like a loft conversion which can massively increase your living space and also the value of your home. 

Mansard roof conversions will always require planning permission, and are likely to also require a party wall agreement between you and your neighbours. When considering a mansard roof conversion, start by looking at your street and seeing if someone has done this before and then consulting with an architect about your project. 

Cost of a Loft Conversion 2024 

The cost of your loft conversion is dependent on a selection of factors. The main factors being, what the structure of your loft is, what you are trying to achieve and where in the country you are as this will massively impact the cost of labour and also materials. 

Check a trade states the average loft conversion in the UK is between £40,000 and £60,000 however, the range of costs falls between £20,000 and £80,000. A roof light loft conversion, where the structure of your roof is a classic cut roof (so the structure is already there) can be achieved for around £20,000, without extras such as plumbing.

On the opposite end of this, a mansard roof conversion can cost up to £70/80,000 and even more in London where the cost of materials and labour is much higher than the rest of the country. (All of the above figures will be subject to VAT and fees which will add another 25-35% to your project.)

Although there is no way of calculating the cost for you without a detailed design, your architect will help you calculate your costs by making it clear what you need to account for. Before you begin your conversion you need to tender prices / account for: 

  • Cost of labour 
  • Cost of consultants - architect and structural engineer 
  • Cost of materials 
  • Cost of planning (if applicable), 
  • VAT 
  • Contingency of at least 10%

Our top tips:

  1. Get more than one quote for the cost of labour
  2. Make sure you check what the labour costs include - does it include everything that you need? 
  3. Use recommendations - ask friends / people you know which architect, structural engineer, builder etc. that they used first 
  4. Shop around for the costs of materials, ask your architect or builder what they recommend for what you are trying to achieve 
  5. Contingency - it is so important to account for as there are always hidden costs you don’t account for
Image by Alan Cragie c/o Konishi Gaffney Architects

Planning Permission / Permitted Development

You may not always require planning permission for your loft conversion as your project (what you want to achieve) might fall within Permitted Development Rights.

Permitted Development Rights are the legal parameters within which you can make alterations to your property without requiring full planning permission. 

Some of the parameters for a Permitted Development loft conversion are: 

  • To ensure that you have not already used your PD Rights on your property 
  • You are not trying to add more than 40m3 (cubic meters) to the roof space in a terraced house or more than 50m3 (cubic meters) to the roof space in any other type of property 
  • Not extending beyond the existing roof slope or the properties principal elevation on the front of the building (road facing)
  • The new roof is tiled in an exact match or an almost exact match to the current roof
  • There are no balconies or verandas, only juliet balconies are allowed

In order to confirm whether your project falls within the parameters of permitted development or not, we recommend consulting with an architect or loft conversion specialist. Our recommendation is to obtain a certificate of lawfulness from your local planning authority to confirm that you do not need planning permission, you will then have proof that any modifications made to your property were approved which can be essential if and when you decide to to sell. 

All other kinds of conversions will require planning permission. It is important to know that any conversion, no matter how small, is likely to require planning permission if your property is a listed building, falls within a conservation area or an area of outstanding natural beauty (AONB) as these areas are protected and there are more specific rules for alterations which will affect the character of the area.  

Consulting with an architect or loft conversion specialist from the very beginning can only be of benefit when making what result in major renovations to your property.

You can book an online consultation with an architect and discuss your property here.

Image by Mark Ashbee

Building Regulations

All loft conversions require building regulations approval as they involve alterations to the structure of your house. For this you can go to your local authority, or use a private, approved building inspector, but it will be required regardless of the need for planning permission.

Your architect, builder or loft conversion specialist can help you to create the loft conversion plans, then you will need a structural engineer to provide all of the calculations required for your project’s approval. 

Building regulations are important when it comes to loft conversions because they consider the structure of your building as a whole, including the walls, floors, beams, stairs, fire safety, windows, electrics, insulation, ventilation and more. 

Hiring An Architect 

Hiring an architect is always recommended, an architect is able to assess your current property, layout, roof structure etc. They are able to best understand what is achievable, in order to see if it will fulfil what it is that you want to create with that space.

Architects are not only able to produce the best layout and design for the stairs and space, but they can also provide the technical drawings required for you to obtain prices/tenders from builders. Architects are also able to help with the entire process of your build, from applying for planning, all the way to completion - if this is something you are not comfortable doing yourself. 

No matter what phase you're at whether it be considering a loft conversion or moving full steam ahead, it is always recommended to get the advice of an architect (this is for any home project).

You can book an online consultation with an architect local to you through our platform Space That Inspires.


It can be difficult to know where to put the stairs up to a roof space. The key when considering this is the need to achieve the correct headroom, and consider how to move furniture into the roof space. The key requirement is that from the centre of the middle of the staircase there needs to be 2m of clear headroom, which can reduce to the sides.

The ideal positioning is for the stairs to discharge into the roof space in line with the roof ridge, but this might not work with the existing floor plan below and the room you’re wanting to create. Stairs are one of the key considerations in creating a loft conversion, hence the need for an architect to assist.  

It is also important to understand that stairs up to a loft conversion are generally bespoke which can make them more expensive than the ‘off-shelf’ stairs you can purchase - something to be considered within your budget. 

Image by Future

Fire Safety and Escape Strategy  

For bungalows, fire safety is less of an issue. The main requirement is that windows are large and low enough for people to escape from or be rescued from in the case of a fire. This varies from a standard house as you may be adding a third or fourth story. 

The four main requirements then are: 

  1. The new floor must be built with 30 minutes of fire protection 
  2. There must be one ‘escape-sized’ window per room (some skylights are made specifically for this)
  3. All doors on the staircase, down to the ground floor must be fire resistant 
  4. There must be a fire alarm connected to the mains electricity on each floor 


If considered from the beginning, ensuring access to hot and cold water within your loft conversion shouldn’t be much of an issue (something you will need your architect / builder to look into). However, there are a number of elements you should consider when including a bathroom in a roof space: 

  • You need a shower where there is enough height to stand 
  • Your toilet and basin also need enough headspace above them to be able to stand
  • A bath can be fitted into the eaves 
  • If you decide on a wet room, the room will need to be tanked 
  • Design the bathroom so you can conceal systems behind stud walls 

Insulation & Sound-proofing 

Due to energy efficiency standards, insulation is much more important than ever before. There are a variety of insulations available, but high performance insulation which minimises thickness is generally preferred. You can either insulate between the roof and above the rafters, if your project requires the roof to come off, or you can cut the insulation and fit it between and then line below the rafters if not. This is in addition to any insulation which might already be required between each floor within the floorboards. 

When it comes to soundproofing, it is not necessary to sound-proof floors, but the fireproofing quite often includes the addition of dense mineral fibre insulation between the floor joists which assists in sound insulation. Sound insulation should be utilised on the walls that connect with your neighbours, highlighted through a party wall agreement. 

Image by Adam Carter


When it comes to timescales, you can never be sure of how long a project will take as each project is so different. Common sense will illustrate, the larger the project, the longer it will take.

As a rule of thumb, a simple roof light loft conversion can be completed in as quick as 2 - 3 weeks, as there is little to be completed. However, a mansard roof which might include a bathroom etc. can take up to eight weeks (and more often longer) as this is a much more disruptive process.

Make sure your builder outlines a schedule of works from the beginning of the project so you can have an idea of the timeline, and help yourself by having materials on site already so there are no obvious hold-ups. 


It is extremely important that you inform your insurance company that you are going to be carrying out these renovations to your home. They should be able to provide cover for the works before you return to your usual policy after the project has come to an end. However, if they are not able to provide cover, you will need renovation insurance. 

Top Tips

Here are some of our top tips for you when planning your roof conversion project: 

  • Take the time to budget carefully (and allow for contingency!)
  • Use experienced / recommended professionals or tradesman 
  • Have all the correct drawings and paperwork before you begin 
  • Make sure you have a schedule of works you are happy with 
  • Try to keep your neighbours happy throughout the project, especially if your renovation is impacting them as well! 


To conclude, a loft conversion is a great way to make use of a dead space and create more space within your home, however it is important to ensure that this is going to give you the result you want to achieve and not be a lot of work for not much space - which can sometimes happen. 

If you would like the advice of an experienced architect on your property, book an online consultation now at Space That Inspires. Our team of architects are here to guide you as to what would be the best project for your home, with no further strings attached.

Book an online consultation with one of our architects, today.

Matthew Montague

Award-Winning Residential Architect

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