Complete Guide to a Loft Conversion

A loft conversion is one the best ways to add space and value to your home without extending its footprint. But how much does it cost and what is the process? In this guide, we explain the whole process from planning to completion and arm you with as much information as possible to start you on your journey.

A loft conversion is considered to be the most cost-effective way to add space to your home whether you are looking for a guest bedroom, a master suite with ensuite bathroom, an extra kids’ bedroom or even a roof terrace. There are so many ways to utilise the space that a loft conversion gives you and it can be tailored to any kind of property. Furthermore, a well-designed and finished loft conversion can add up to 25% to the value of your property (according to a study by Nationwide carried out in 2023).

There are quite a few considerations needed before embarking on a loft conversion and therefore it is crucial to know exactly what kind of project you are starting and what it might entail. Some of the key questions include what Building Regulations do I need to comply with? Am I entitled to undertake the works through Permitted Development rights, or do I need planning permission? How much will all this cost?

Can my loft be converted?

Not all roof types are suitable for a loft conversion due to head heights, roof pitch and roof structure. That is not to say that a loft conversion cannot be possible. Some roof types might require more structural work or a specific type of loft conversion to meet requirements. Traditional framed roofs in Edwardian or Victorian houses are the most suitable and, in London, the most typical for a loft conversion. These types of roofs allow the space to be opened up relatively easily and inexpensively. Other types of roofs such as trussed roofs can also be converted but would require more structural work, typically needing the addition of steel beams between the loadbearing walls and the floor joists and at the roof ridge. Furthermore, things like water tanks and plumbing may have to be moved.

What head height do I need?

It is advisable to have at least 2.2m of head height (usable space) for a loft conversion. There is no set height set by Building regulations with the exception of head height above the stairs. A dormer loft conversion is the best way to maximise the head height and usable space in a loft conversion. The higher the roof pitch the higher the central head height will be in the loft. If your roof pitch is less then 2.2m it doesn’t mean that you can’t convert your loft, there may be a possibility to replace the whole roof structure to raise the ridge height or to add a mansard loft conversion. Although more costly than a simple dormer loft conversion, it will ensure you will get ample head room and sufficient usable space in your loft conversion.

Do I need planning permission for my loft conversion?

Planning permission is not required in all cases. Most loft conversions tend to fall under permitted development rights. The government has published a technical guide to permitted development rights in the UK - https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance. 

In summary, permitted development rights apply to certain types of works carried out by homeowners without the requirement for planning permission. That said, any works carried out under permitted development rights are subject to certain standards and criteria limiting the maximum size of the loft conversion, but these limits are quite generous. For a quick reference guide, the Federation of Master Builders (FMB) have published a handy guide on the permitted development criteria for loft conversions - https://www.fmb.org.uk/find-a-builder/ultimate-guides-to-home-renovation/permitted-development-rules-what-you-need-to-know.html. 

If your loft conversion doesn’t fall under permitted development rights, as is often the case when you need to raise the roof ridge height such as with a mansard loft conversion, then you must apply for planning permission. Even if your loft does fall under permitted development, it is a sensible option to obtain a certificate of lawful development.

Do I need an architect for my loft conversion?

Whilst a loft conversion can seem quite standard thing to design, it is always advisable to engage the services of an architect or a designer. Creative Spaces offer this as part of their loft service. Our team of architectural technicians can offer the best advice and guidance on how best to utilise and design your loft space. Engaging a designer helps you to plan your space exactly to your specifications and, with an experienced designer onboard, they are able to offer you plenty of advice and guidance on the best way to layout the space and how your ideas will work in reality. A design and build company such as Creative Spaces takes the stress out of having to engage an architect and structural engineer, all of these services along with the build is rolled into one package.

How much does a loft conversion cost?

A loft conversion in London can cost anywhere between £40,000 and £95,000 depending on the specification and size. It is very important to get a detailed breakdown of costs from you builder so you can see exactly the costs for each part of the building work. It is also helpful to be able to compare quotes and identify where there may be price differences.

What impacts the price and how is the quote shaped? Quite simply specification is the biggest variable in your loft conversion pricing. The starting point for any quote is generally your vision or what you want to achieve with your loft conversion. Will it be a luxurious master suite or a guest bedroom and home office or a kid’s space. The purpose of the space can influence the complexity and the cost. Another factor in the overall pricing is how much do you want to do yourself? Typically, a shell loft conversion will be cheaper than a completely finished loft conversion. Are you going to do the painting, tiling or floor finishes or leave it to the professionals? Design details have a large factor to play in price variations. Do you want simple Velux windows or dormer windows or would you want bespoke built in storage or carpentry work done or just some simple shelving? The reality of the existing and new roof structure is also something to consider with cost alongside cladding materials on a dormer loft extension. All of the quotes we provide are transparent and breakdown all of the costs involved. Our aim is to maximise the value for you as the client and ensure that the project meets your expectations.

What are the Building Regulations and Party Wall rules for a loft conversion?

Compliance with Building Regulations is absolutely necessary for any loft conversion (irrespective of whether it is done under permitted development or it needs planning permission). We prepare all the plans necessary to comply with building regulations including structural specifications and calculations and ultimately, we ensure that your project complies with building regulations to ensure you get approval. An approved appointed Building Control officer will inspect the work at various stages to ensure it complies at major stages of the build process. This is something we organise for you. If your house is semi-detached or terraced or works are on a shared wall, you need to notify your neighbours which falls under the Party Wall Act 1996 - https://www.gov.uk/government/publications/preventing-and-resolving-disputes-in-relation-to-party-walls/the-party-wall-etc-act-1996-explanatory-booklet. This is a process we provide guidance to all our client with, but ultimately it is up to complete the party wall process with your neighbours. The party wall agreements must be in place before starting any build project.

How long does a loft conversion take?

The length of time it takes to do a loft conversion is standard 8 to 10 weeks but this can vary depending on the size of the project and weather. At Creative Spaces we always provide a project plan which is a detailed plan of each stage of the build and how long each stage should take. There is also the initial design, engineering and planning / permitted development stages to consider. This process can take up to 10 weeks to complete before any building on site can start. The most important thing to remember is to plan the works. Your design and build company is perfectly placed to do this all for you from design through engineering to staging the build works.

What are the phases of the build?

Once works start on site the typical phases are:

Demolition and preparation: It is important to prepare the space for the build teams, clearing the loft space and ensuring access through the house. The build team will ensure that appropriate protection is applied to areas that they have to move through. The build team will then remove a lot of the larger items such as water tanks, reroute electrics or plumbing services and begin on demolition.

Framework and flooring reinforcement: The build team will then look at reinforcing the flooring by installing new floor joists for stability followed by wiring and plumbing infrastructure.

Insulation: The builder will install new and replace old insulation throughout the floor and roof space that will maximise energy efficiency and be compliant with current building regulations.

Structural roof framework: The build team will install the rafters to take the additional load of the new roof, new tiles and remove all the redundant elements of the existing structure.

Adding features: At this point things like dormer window openings, roof light spaces or Velux window positions will be determined and the structures for these put in place.

Access provision: The staircase will then be installed and integrated with the first floor providing a seamless access route to the new loft conversion.

Weatherproofing the shell: The external tiling and cladding will be completed at this stage making the structure weather tight and waterproof. Windows will be installed at this stage too.

First fix and space definition: Once weather tight, the build team will get started on partitioning the space with studwork, insulation and plasterboarding. Pipework for plumbing and wires for electrics will be run throughout the spaces too.

Access and storage: This is when under eves storage can be created in order to maximise storage and access panels to hidden services can be determined and installed.

Second fix: This is in when plaster skimming will take place, architraves and skirting will be installed and the completion of electrics (installation of light fittings, sockets and switches) and plumbing (sanitary ware install, plumbing systems and radiators) will be done.

Decoration: This is the final phase where flooring, tiling and painting is completed where you loft space is transformed into your new space.

Snagging: Where the project is gone through in detail and anything that needs finishing or changing is completed.

Completion and hand over: All certificates have been handed over including the Final Building Control certificate and the space is signed off as complete.