How much does a dormer loft conversion cost and are there ways to save?

How much does a dormer loft conversion cost? It is a much-asked question by those keen to add extra space to their homes without extending outwards.

As with all types of loft conversion, the answer will vary depending on a number of factors, such as where in the country you live, how big you want the conversion to be, the current state of your loft and how you plan on using your newly-formed space. 

As one of the most popular styles of loft conversion, dormer loft conversions are a commonly undertaken project and can not only add lots of useful extra space to a house, but also value.

In this guide, we explain how much this project usually costs, the factors that are most likely to push prices up and – more importantly – ways you can potentially save at the same time as being happy with the outcome. 

What factors affect dormer loft conversions most?

There are so many variables to take into account when considering loft conversion costs meaning that the price your neighbour paid for their loft conversion is likely to be quite different to the quote you receive.

Factors that will influence what you pay include:

• The area you live in
• What type of roof construction your house has
• The size and complexity of your proposed conversion
• What you plan on using the new space for
• The spec you are aiming for

How much does the average dormer loft conversion cost?

"A typical dormer loft conversion cost can vary between £50,000 up to £60,000 depending on the specification of the build," advises Robert Wilson, managing director at Simply Loft. "Average dormer loft conversion costs can vary quite dramatically depending on where you are located and the finer details of what you require internally in your loft conversion. For an accurate dormer loft conversion price, it is important that you seek the expertise of a loft conversion specialist."

As mentioned, the area in which you live will have a strong part to play in how much your dormer loft conversion costs – and if you own a property in London, you will be looking at higher than average costs in all liklihood.

"The average cost of a London loft conversion ranges from £50,000 to £90,000, depending on factors such as design, specifications, size, and location," says Robert Wood. "From windows and doors to bathrooms and more, the internal specifications also play a role in determining the overall cost."

Are there cheaper options than a dormer loft conversion?

Dormer loft conversions are classed as mid-priced when compared to other types of loft conversion, meaning that while there are cheaper alternatives to a dormer loft conversion, they are not the most expensive either.

According to Simply Loft, the average rooflight loft conversion comes in at around £50,000.

"Skylight loft conversions, which require fewer materials, and loft pods or L-section only loft conversions are typically considered small conversions, and therefore tend to be less expensive than larger projects," says Robert Wilson.

Mansard loft conversions and hip-to-gable conversions sit right at the top of the scale with an average price of between £60,000 - £70,000.

Will a dormer loft conversion add value to a house?

The good news here is that, while adding a dormer loft conversion to your home is obviously going to make a dent in your bank balance, just as when building an extension of any kind, it will also add value – as well as coming with many benefits to those who don't plan on moving on any time soon. 

"The precise value that a loft extension can contribute to a property can vary considerably, influenced by factors such as the property’s location, the quality of the extension, and the local market," explains Robert Wilson. "Generally, a well-designed and skilfully executed loft extension has the potential to significantly enhance a property’s value.

"According to a 2019 study by the Nationwide Building Society, a loft conversion in London can add an average of 20% to the property’s value, surpassing the national average of 10%," continues Robert. "It’s important to note that this figure represents an average, and the actual value increase can be higher or lower depending on the unique characteristics of the property and the prevailing market conditions."

Robert Wilson

Robert Wilson is managing director at Simply Loft. He founded Simply Loft with his wife Helen Wood in 2008 when he left his full time career in project management of railway and underground construction in London to set up firstly the Simply Extend brand and in 2010, Simply Loft. It started with a vision of creating a domestic or residential building company that would focus on delivering home improvement including kitchen extensions, loft conversions and more recently basement conversions in a simple and clearly structured way with a strong focus on customer care. 

How can you reduce dormer loft conversion costs?

If you are on a tight budget and after after ways to turn your dormer loft conversion ideas into reality without overspending, there are several ways you can keep a lid on costs.

"The simplest option to convert your loft is to hand the project over to a specialist design and build contractor, or to an architect who then helps you find and manage a builder, but there is a cost for paying someone else to manage the project for you and take on the stress," says Sarah Potter, head of marketing at Home Owners Alliance. "If you have the time and knowledge required to hire subcontractors, buy materials and manage the build, you can reduce costs by 10-20%.

"Choice of materials and finishes will also affect cost, with simple off-the-shelf standard rooflights, stairs and standard design details being the most cost-effective, and bespoke windows, stairs and cabinetry all adding significant cost," continues Sarah.

She goes on to explain that avoiding a design that will require planning permission will also help keep costs low.

Paula Higgins

Paula Higgins,  CEO of Home Owners Alliance, spent 15 years reforming housing policy in government before deciding enough was enough. Homeowners needed a voice and HomeOwners Alliance was born.

Q&As

What is a flat roof dormer loft conversion?

There are several different types of dormer loft conversion – with the flat roof style being just one of them.

"The flat roof dormer loft conversion is a simple structure that can be added to the front and/or rear of the loft," explains Robert Wilson. "It provides a fairly simple way to expand the usable space in the loft, increasing head height and providing lots of natural light afforded by the dormer windows." They can be single or full-width.

Do dormer loft conversions take a long time to build?

Not when considered alongside some other types of loft conversion, such as mansard. 

"The average time it typically takes for a dormer loft conversion to build is four and a half weeks," says Robert Wilson. "It could take one or two weeks longer to complete depending on the type of dormer loft conversion."

While dormer loft conversions are a great way to add space and value to your home, don't discount a Velux loft conversion too quickly. This is one of the simplest and most affordable options and rarely requires planning permission.