Are you an adviser? Go to Unbiased Pro

How much value will a loft conversion add to my home?

6 mins read
by Unbiased Team
Last updated Friday, March 1, 2024

A loft conversion can be a great way to increase space and the value of your property. But how much value will it add and is it worth it? Learn more here.

When it comes to adding value to your home, the most cost-effective options normally involve increasing usable floor space.

loft conversion is a common solution, as that previously neglected storage can become a new bedroom or office.

But just how much value this conversion adds depends on a range of factors that need careful consideration before you take the plunge.


  • A loft conversion can add an extra 20% to a property's value.

  • The starter cost of a loft conversion can be between £12,500 and £20,000, but can be much higher.

  • Not every loft is suitable for conversion, so it's important to carry out checks.

  • The time it takes to complete a loft conversion is typically around four to five weeks.

  • A loft conversion is generally cheaper than an extension, making it a budget-friendly option.

So, what kind of value could a loft conversion add to your home?  

A loft conversion that adds a double bedroom and bathroom to a three-bed, one-bathroom house can add about 20% to its value — a substantial gain.

In London, the increase can be even bigger, where adding a loft conversion to a two-bedroom house can boost value by 24.5%.

The first thing to consider is the price ceiling for your house, given the type of property and the area you live in.

For example, if you live in a three-bedroom house worth £300,000, but the maximum price for a four-bedroom house is around £320,000, you’ll be hard-pressed to add any real value by adding a loft conversion.

In contrast, if most houses in your area are three-plus bedroom designs, but yours only has two, it could make a real difference to add that extra living space with a loft conversion.

How much does a loft conversion cost?

Currently, the average cost of converting your loft space into a bedroom with windows will be at least between £12,500 and £20,000.

If you want to add an en-suite bathroom, this will increase to £17,500 – £25,000.

Costs could increase by up to £15,000 if you live in the London area.  

The exact cost of your conversion will depend on a whole range of factors, such as: 

  • The structure of your roof

  • Whether your house is detached, semi-detached or terraced

  • The type of conversion — to include dormer windows, for example

  • How much space is available

  • The extent of alterations needed to fit a staircase

  • Location — conversions are more expensive in the London area 

Other details could significantly alter the cost of your conversion.

If you need to raise the roofline or lower the ceiling below, this kind of structural work can be expensive.

Always get a few quotes to compare costs before choosing a construction company. 

Is my loft suitable for conversion?

Not every loft is suitable for conversion, so your first step should be to make sure the job will be possible or cost-effective.

Here’s a list of key elements to check. 

  • Roof height: The distance between the ridge timber and ceiling joist should be at least 2.2 metres to meet minimum bedroom size regulations.

  • Roof pitch: A higher pitch angle will provide more central height, which will make conversion more feasible. 

  • Roof structure: Most UK homes have either traditional framed or truss sectioned roof designs. The traditional type, usually found in pre-1960s houses, is relatively easy to alter and reinforce for a loft conversion, while the more modern truss section type will almost certainly need extra reinforcement and work. 

  • The water tank. Converting your loft into an extra bedroom will almost certainly mean relocating your water tank or replacing it with a closed system. A new, unvented hot water cylinder is probably your best bet, but you’ll need a cupboard space somewhere else in the house for it. 

Benefits of a loft conversion

Some of the main benefits of having a loft conversion include:

  • Extra living space: Converting your loft adds valuable square footage to your home without the high costs of moving.

  • Increases property value: Adding a loft conversion can increase the value of your home by 20% typically. This provides a good return on investment if you ever sell.

  • Makes better use of wasted space: Most lofts are just used for storage. Converting it allows you to get more practical use out of the space.

  • Personalisation: You can customise the loft space to suit your needs and style.

  • Saves energy: Converting the loft can improve home insulation and reduce heating costs.

  • Add value without moving: A loft conversion allows you to expand without relocating your family.

How long does it take to convert a loft?

The time it takes to complete a loft conversion can vary, but you can typically expect the process to take four to five weeks from start to finish.

The exact duration will depend on factors like the amount of preparation and construction work required, as well as whether any unexpected issues arise. 

Completing a loft conversion involves three key phases that allow the project to run efficiently. These phases are:

  • Phase 1: Design

  • Phase 2: Planning

  • Phase 3: Building

It's important to factor in possible delays or disruptions in the above phases, which could impact the time it takes to complete your loft conversion.

But with good planning and execution, the three phases can be completed smoothly to transform your loft on time and in budget.

Loft conversion vs an extension: which is cheaper?

A loft conversion is generally cheaper than an extension, making it a good budget-friendly option.

However, an extension can offer greater space, square footage and flexibility, making it a more suitable for those wanting a larger living area or extra bedrooms.

What else should you consider? 

You don’t need to worry about getting planning permission for a loft conversion, but you will need a building control surveyor to inspect your conversion during the project.

They will make sure your loft conversion meets the minimum required standards.

If your home is semi-detached or terraced, you must also let your neighbours know about your plans. 

Find out how to get official approval for your build at the Planning Portal.  

Building work gets messy, and some fixtures and furnishings may get damaged or dirty with teams of people in and out of the house over several weeks.

It’s a good idea to consider the cost of potential repair and decoration at the start.

Also, make sure you’re ready for a degree of domestic upheaval, as even a simple conversion will involve some hiccups and periods when water and electricity are unavailable. 

Lastly, be sure that adding a third bedroom will add value to your property — it’s not just about a simple room count, after all.

By converting your roof space into a third bedroom, you’re competing directly with houses designed to be larger from the start and offer more all-round living space.

Your newly converted home may not generate the appeal — or the price tag — of these larger-scale properties.

Before converting, consult

There’s no doubt that a loft conversion can add substantially to the value of a house, and it’s a tempting proposition when moving seems more expensive and uncertain.

But it’s a good idea to do your research carefully before committing.

You need to understand all the positive and limiting factors that affect your property before embarking on a conversion.

That’s why you should start by seeking the expert advice of a trusted construction professional and an estate agent with knowledge of your area.

Look at other developments close by to get a feel for what works.  

If you found this article helpful, you might also find our article on how much value a garden office could add to your home informative, too.

Get mortgage advice
We’ll find a professional perfectly matched to your needs. Getting started is easy, fast and free.
Find a mortgage broker
Unbiased Team
Our team of writers, who have decades of experience writing about personal finance, including investing, retirement and pensions, are here to help you find out what you must know about life’s biggest financial decisions.