How much value does a dormer loft conversion add to a property?

A property that once offered plenty of space for you and your family, now suddenly seems cripplingly small – it’s a dilemma that most homeowners will face at some point. As might be expected, you begin to ask yourself whether it’s time to pack up and move somewhere bigger.

But moving houses is a major upheaval. The costs alone involved with selling and buying properties can be off-putting. Stamp duty, surveys, legal fees and more could amount to several thousand pounds; money you will never get back. Not to mention that it can be stressful for you and your family, considering the emotional attachment to your home and the possibility of your children changing schools. Fortunately, buying a bigger house isn’t always necessary, you can always extend your current property.

Often people think about extending horizontally – whether that’s adding a conservatory or building a room above the garage – but you can also extend upwards by building a dormer loft conversion. Building upwards instead of outwards won’t impede on your home’s precious outside space, and extending upwards means you are able to increase the number of rooms in your home – solving the space issue – and also adding value to your property. Dormer loft conversions add space, light, and a useable living area to your home, making it more appealing to potential buyers down the line and putting you in a position where you stand to make back the money you spent – and then some – when you do eventually sell.

To help make your mind up, in this article we’ll be taking a look at how much value a dormer loft conversion adds, the benefits of a loft conversion as opposed to other forms of home improvements, and some things to take into consideration. Let’s jump right in.

How much value does a dormer loft conversion add?

When it comes to making home improvements and adding value to your property, a dormer loft conversion is regarded as one of the most cost-effective ways to add value to your home. Research conducted by Nationwide Building Society found that adding a loft conversion that incorporates a bathroom and double bedroom could add as much as 22% to the value of a three-bedroom property. With the average property in the UK being valued at £277,000, theoretically, that would result in a staggering £60,940 increase in value. That’s a lot of extra money to cash in on if you decide to sell in the future.

A loft space conversion appeals to most people since it makes the best use of ‘dead’ space in order to create an extra room in your house, as opposed to eating into valuable outside space in your home. Additionally, it typically costs less per square metre to convert your loft rather than building a traditional extension since the bulk of the structure required for a conversion is already in place.

How do I know if a loft conversion will add value to my home?

It is important to keep in mind that every house has a price ceiling; the maximum price that a house can realistically sell for given its location and property type. For instance, if you own a three-bedroom house worth £250,000 and the maximum price for a four-bedroom home in your area stands at £270,000, you will probably see little increase in house value from your loft conversion.

On the other hand, if you currently own a two-bedroom property and most other houses in your area have three or more bedrooms, a loft conversion would be essential to make your property more appealing to buyers and thereby add value to it.

Is your loft suitable for conversion?

Before you decide to spend your money on loft conversion designs and building works, you must first consider if your property is even suitable for a loft conversion – though most houses, even terraced, will be fine. Assessing the suitability of your loft conversion will depend on certain criteria:

  • Roof Height – A minimum of 2.2 metres of head space is required. Loft conversions with restricted head height can only be used as storage space, therefore the cost and scope of the project will increase if the roof space will need to be extended, for example, raising the roof or lowering the ceiling in the room below, and will also require planning permission.
  • Roof Structure – Traditional rafters – found in pre-1960 houses – are more suitable for conversions as they run along the edge of the roof, leaving more space below. A modern trussed roof will require more structural reinforcements since these supports run through the cross-section of the loft, increasing the cost of the project.
  • Staircase – Whether there is enough room on the floor below to provide for a staircase that complies with Building Regulations.
  • Floor Joists – If the current floor joists aren’t strong enough to hold the weight of a loft, deeper joists will need to be introduced, or steelwork for support.

There are various other factors that could affect the suitability of your loft conversion. Qualified professionals like architects, builders, or a specialist loft conversion company will be able to advise you on all structural and design-related changes that would need to be made in order to build convert your loft into a liveable space.

How much is the average cost of a loft conversion?

As with any home improvement, your loft conversion cost will depend on numerous factors, such as:

  • Roof structure
  • Type of house (terraced, semi-detached, detached)
  • Available space
  • Location (costs in London will be considerably higher than in the North East)
  • Alterations required on the floor below (e.g. to accommodate a staircase)
  • Placement of an en-suite bathroom
  • Whether you need planning permission

According to PriceYourJob, the cost of an average dormer loft conversion can fall between £15,000 – £45,000. That’s a fairly wide range, but this is due to the factors mentioned above.

You will pay considerably more if the property requires significant structural work to accommodate the conversion. But, when you compare the costs of the loft conversion to the potential added property value, it is one of the most cost-effective home improvements options available.

Very few, if any, other forms of home improvement cost so relatively little yet add so much value to your house; including a conservatory, kitchen remodels, or a ground-floor extension.

Moreover, the majority of home extensions require planning permission; for most loft conversions, this is not the case. However, as with all home improvements, we recommend getting quotes from at least three different companies to get an accurate idea of the true cost and scope of the project.

How to get the most value out of your loft conversion?

Once you’ve made the decision to greenlight your loft conversion, the fun part begins – choosing what to do with the new space. The extra room can be used for whatever you like, but if you’re looking to maximise the potential value added to your property, there are a few key areas that you may wish to focus on.

Additional living space

An extra bedroom will add the most value to your property. You’ll need to ensure the space is not only practical but also cosy, especially if the room is being used as a bedroom. To make most of an additional bedroom, you will want to consider including a bathroom, wet room, or en-suite. Of course, these facilities will incur greater up-front costs, but they could significantly increase the value of your house, especially long term.

Natural light

A loft conversion will provide the top of your house with ventilation and plenty of natural light. Dormer windows will let in much more light than the other windows in your home since they are much less likely to be blocked by trees or other houses on your street. So, with careful planning and installation of high quality, properly implemented windows, the loft can be made to look much brighter and bigger than it is, thereby more appealing to prospective buyers.

See what’s trending

Certain types of rooms can make your home more or less desirable. In the aftermath of the pandemic, with more people working from home, options such as offices or home gyms – although maybe not adding much value directly – are becoming increasingly popular. As such, extra space such as these may appeal to people who would be willing to pay above the property’s asking price. Knowing this, it is a good idea to research current trends to find out how best to convert your loft space into the kind of room that’s in high demand.

Energy Efficiency

Loft conversions done correctly can make your home much more energy-efficient. For example, many companies will simply install the minimum required amount of insulation, but it’s a good idea to ask for more since increasing the amount of insulation in your loft will protect it from extreme temperatures. Combine this with fitting highly energy-efficient windows, it will not only retain heat in your loft, but your whole house, and you could save on your heating and utility bills, further increasing the value of your property.

Rent it out

If you decide to turn your loft conversion into an extra bedroom to be used for guests, you could consider renting it out to generate supplementary income. Typically, you would have to pay tax on rental income, but with the UK Government’s Rent a Room Scheme, you can earn up to £7,500 per year tax-free for letting out a furnished spare room in your home. Combined with the added privacy of a loft room, it will have added appeal for tenants.

Needless to say, this option is not for everyone, but it is a great way to see a return on your investment without having to sell your home.

What are the downsides of dormer loft conversions?

Based on the above, converting your loft seems like a no-brainer. However, as with any home improvement project, there will be downsides and a loft conversion is no different.

There’s the hassle involved throughout the construction process, alongside time and money spent on potential planning permissions and surveys that could be required for your renovation. Although a loft conversion is the best cost-effective method, it is still an investment that can add up.

Potential damage

Home improvement projects can often run into problems, some of which could lead to damage to your home. For instance, with workmen walking in and out of your house over the course of a few weeks, there’s a chance there will be some cosmetic damage to your home, such as your carpets which may require replacing. Or, when implementing plumbing for a bathroom for your loft, a water leak could lead to severe water damage throughout your house. Although certain things can be limited by hiring highly-skilled professionals, there’s no guarantee that your project will go smoothly.

Living arrangements

If it does run smoothly, a dormer loft conversion can take as long as eight weeks to complete – the simplest of conversions will still likely take up to a month. Any complications will certainly add a significant amount of time to this, which can be quite challenging for families to deal with such disruption.

What planning permissions are required to convert a loft?

In most cases, your home won’t need planning permissions as there’s a good chance the conversion will fall under ‘Permitted Development’, meaning no lengthy planning processes will be required to get work underway. However, it’s crucial that your loft conversion is compliant with certain specific limits and conditions:

The most important is the loft’s volume allowance – an allowance of 40 cubic metres of additional roof space for terraced houses and 50 cubic metres for detached and semi-detached houses. This includes existing roof additions that were completed by previous owners. Also:

  • The conversion’s height cannot exceed the highest part of the existing roof
  • The roof enlargement cannot overhang the outer face of the original building’s wall
  • A balcony, raised platform, or veranda is not permitted

For full technical guidance, the government’s guide on Permitted Development Rights for Householders outlines all conditions in detail.

What is building regulations approval and will my loft conversion require this?

Building regulations are the minimum required standards for construction, design, and alterations to every building. It will ensure that the work being done is carried out safely and to the highest quality. Whether your loft conversion requires planning permission or not, it will always need building regulations approval to cover the alterations necessary to transform your loft into a liveable space. Examples include the following:

  • Structural integrity – e.g. new floor joists to support the loft’s weight
  • Fire safety – mains-powered interlinked smoke alarms, and fire-resistant doors
  • Stairs – Retractable ladders/stairs aren’t usually accepted for loft conversions; a permanent solution may be required
  • Party Wall Agreement – Loft conversions in terraced or semi-detached properties may affect the wall(s) of adjoining properties. Thus, you’ll have to provide your neighbour with a Party Wall Notice summarising your plans.

For a full detailed explanation on what to be aware of, visit the government’s Building Regulations Approval guide.


A dormer loft conversion is one of the most cost-effective ways to add significant value to your property. Adding up to 22% more value with a relatively low cost, it can be an easy decision if you want to increase the living space in your home without potentially having to go through the planning permission process.

As with any property improvement, regulations will have to be adhered to, however, loft conversions can be one of the simplest forms of extending your home, which is why if you want to increase space for your growing family, or add value in order to sell your property, a loft conversion is a great option.