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Home & garden.

30 June 2021

Loft conversions: step-by-step guide

Find out how to get started on your loft conversion with our expert advice on working out whether your loft is suitable, choosing the type of conversion and finding a builder or architect.
Which?Editorial team
Architectural drawing 436691

There are a lot of seemingly complicated steps to getting your loft converted, so knowing where to start can feel daunting. But fear not, as Which? is here to help make the process feel easier to manage.

In this guide, we'll explain the key stages of a loft conversion and tell what you need to consider each step of the way.

Can my loft be converted?

Before you do anything else, you need to work out whether your loft space is actually suitable for a conversion.

Most houses will come with an allowance for permitted development, which means that you can go ahead with your conversion without planning permission. However, if you live in a conservation area, or if, for example, your roof space isn't tall enough, it may be more complicated.

You can ask a builder, architect or surveyor to visit your home and check this out for you, but there are also a couple of checks that you can carry out yourself prior to this.

Look for other conversions on your street

An easy way to get an idea of whether your loft can be converted is to see whether any similar houses on your street have had loft conversions. If you do spot examples, it's more likely to be a possibility. If you can, it's also worth going one step further and asking to take a look at the loft of anyone in your street that has had it done.

Measure the head height

The minimum height you need for a loft conversion is 2.2m, and you can easily measure this yourself. Take a tape measure and run it from the floor to the ceiling at the tallest part of the room. If it's 2.2m or more, your loft should be tall enough to convert. Victorian houses tend to be lower than those built from 1930 onwards, so may not have sufficient head height.

Check what type of roof you have

Depending on when it was built, your house will either have roof trusses or rafters. By looking through your loft hatch, you should be able to tell straight away what type of roof you have.

Rafters run along the edge of the roof and will leave most of the triangular space below hollow. Trusses are supports that run through the cross-section of the loft. Converting a loft with trusses is possible, but extra structural support is needed to replace the trusses, and it's likely to be more costly. You can see examples of these in the gallery below by scrolling to the final two images.

Consider the floor below

Many people neglect to factor in changes to the floor below the loft when planning a conversion. It's worth having a think about where the staircase is likely to go and how much room it might take up. Even a well-designed space-saving staircase could take up a sizeable chunk of a room, so make sure you have space you're happy to lose.

Once you've assessed whether you are able to have a loft conversion, it's worth visiting our page on loft conversion costs, which includes average prices and tips from experts and people who have had a loft conversion on how to keep costs down.

Which type of loft conversion should I go for?

There are four main types of loft conversion: roof light, dormer, hip-to-gable and mansard. The one you choose is likely to be determined by a number of factors, including the type and age of house you live in, and your budget.

Flick through our gallery below to see examples of each type, and read on for more details on how they work, what types of houses they would suit and how costly they are.

Loft conversion types

A large collection of images displayed on this page are available at

Roof light conversions

Roof light conversions are by far the cheapest and least disruptive option, as you won't have to make any changes to the shape or pitch of the roof. Instead, it's simply a case of adding in skylight windows, laying down a proper floor, and adding a staircase to make the room habitable. However, you'll need to have enough roof space already without having an extension for this type of conversion.

Dormer conversions

A dormer loft conversion is an extension that protrudes from the slope of the roof. Dormers, in particular flat-roof dormers, are the most popular type of conversion. They are suitable for pretty much any house with a sloping roof. 

Dormer conversions are less expensive than mansard or hip-to-gable conversions, but will still add a good deal of extra headroom and floor space.

Hip-to-gable conversions

Hip-to-gable conversions work by extending the sloping 'hip' roof at the side of your property outwards to create a vertical 'gable' wall, creating more internal loft space. This type of conversion will only work on detached or semi-detached houses, as it requires a free sloping side roof. 

If you have a detached house with sloping roofs on either side, you can build on both of these to create an even more spacious double hip-to-gable extension. 

Mansard conversions

Mansard extensions run along the whole length of your house's roof and will alter the angle of the roof slope, making it almost vertical. These tend to be the most expensive type of conversion, but will result in a significant amount of extra space. 

Mansard conversions are suitable for most property types, including terraced, semi-detached and detached houses.  

How do I choose a builder or architect?

When hiring any tradesmen, it's best to start with a recommendation. Speak to friends and family, and have a look online to see if there are any local forums offering recommendations.

If you've spotted any loft conversions along your street and you feel comfortable knocking on some doors, ask your neighbours who they used and how they found them. 

You can also find local traders that have been given our seal of approval by heading to Which? Trusted Traders. You can also use our Trusted Traders search tool below to search for a trader.

When speaking with a builder or architect, ask to see examples of previous work. Most reputable companies will be happy to provide you with photographs, and some may be able to organise visits so you can speak to customers about their experiences and see conversions that they've completed up close. 

It's a good idea to get at least three quotes for the work that you're planning, but be sure to factor in recommendations and your gut feel on the person or company, as well as price.

Will I need planning permissions?

Many loft conversions are covered by permitted development rights and won't need planning permission. 

However, if you live on designated land or have a certain style of property that's tricky to convert, you may not be covered by permitted development.

You can find out more about whether you'll need planning permission, and any other permissions you might need, by visiting our guide to building regulations and planning permission

Should I tell my home insurance company about a loft conversion?

Yes, you should tell your insurer about any changes that will alter your home’s structure, habitability, security or value. For example a loft conversion may increase its value. This will likely affect your buildings and contents insurance premiums.

If you’re staying elsewhere while your loft conversion is completed, then you should tell your insurer about this too. Try to give several weeks’ notice.

If you’re having serious building work done, consider specialist renovations insurance. This covers against things going wrong with the building work, materials and property owners’ liability.

Find out more about home insurance.