Dormer Loft Conversion Cost

Looking to convert your dormer loft and wondering what the prices would be? In this article, we discuss the average dormer loft conversion cost in addition to other matters relating to it including factors that determine the price, the process of dormer conversion, types of dormer conversions, its benefits, building permissions required and more.

Dormer Loft Conversion Cost
Source: Love Renovate

How much does dormer loft conversion cost?

Let’s get right to it.

Depending on the size of the conversion, the finish quality, the size of the property, the installation area, and the ease of access, the cost of a dormer loft conversion ranges in general between £30,000 to £60,000.

What are the costs made up of?

This sum is made up of numerous smaller fees that are necessary to ensure that your conversion is successful and carried out to a high standard. How much would it cost to use a dormer to add a new master bedroom and bathroom?

Usually, the price for a master bedroom with an ensuite will fall between £35,000 and £45,000 on the higher end of the scale.

Dormer loft conversion cost estimates

Here’s a rough estimate of dormer loft conversion cost that you can use as a guideline.

  • Typically, a small dormer loft conversion costs between £4,000 and £8,000.
  • The cost of a medium dormer would range from £10,000 to £30,000.
  • The price range for a larger-scale loft conversion is between £35,000 and £60,000.

The table below outlines the cost estimates based on the 2, 3 or 4 bedroom houses.

Two-bed terraceThree-bed semiFour-bed detached
Number of dormers222

All of these costs vary depending on the installation type selected, and additional customizations (type of roof, en-suite conversion, etc.) may alter the cost in accordance.

The additional materials and labor needed by the tradespeople to finish these additions are what caused the price to change.

Dormer loft conversion with a double bedroom5 weeks£18,000£15,000
Dormer loft conversion with a double bedroom and en-suite6 weeks£20,000£20,000
Twin dormer loft conversion with a double bedroom and en-suite8 weeks£23,000£25,000
Extension of the mansard loft with a double bedroom and en suite10 weeks£30,000£30,000

Cost of loft conversion only

You can see how the total quote is calculated in the tables we’ve created below, which illustrate the various costs:

Loft Conversion Windows

50 x 50£200-£250
100 x 100£250-£300
120 x 120£350-£400

General Building Materials

Structural beams, joists and masonry£2,000-£5,000
Decorating materials£800-£1,800
Built-in Storage£1,500-£10,000

Loft Conversion Insulation


Loft Conversion Flooring


Loft Conversion Stairs

Alternating Treads£550-£950
Fixed ladder with Bbanister£250-£500

Dormer Conversion Cost for labour

Typically, there will be 2 or 3 people on-site at all times during a large-scale project. The variance in timeline will frequently depend on how simple it is to schedule each tradesperson, and weather conditions may also have an impact.


Building regulation costs 

Regardless of your planning status, the building regulations division of your local authority will need to inspect your dormer loft conversion to make sure it is being built in compliance with the rules, making sure it complies with things like fire safety, access, floor strength, and so on.

Costs for submitting the plans for review and for on-site inspections can range from £500 to £1,000.

If your work will have an effect on any neighboring properties, such as if you live in a terraced or semi-detached house, you might also need a Party Wall Agreement. Your neighbors must consent to the work being done in order for this to happen.

Factors that affect Dormer Loft Conversion Cost

The size of your conversion and the actual property itself are two variables that can affect the cost of your conversion.

A typical 5×4 m2 loft conversion with one dormer will run you between £30,000 and £35,000 overall. In contrast, the price range for a two-dormer, two-rooflight conversion in a 5 x 6-m2 area is between £40,000 and £45,000.

Of course, the price can vary depending on the quality of the conversion, the materials you select, and the cost differences between various contractors and laborers.

Depending on the type of room you are building, additional costs may arise. For instance, you would have to pay for plumbing and fixtures if you wanted to build a bathroom.

Dormer loft conversion process

A major contributing factor for domer loft conversion cost is the efficiency in which the process is carried out. Most qualified contractors will follow the standard procedure to improve efficiency and pass on the cost saving to homeowners like you.

A loft conversion is a significant undertaking that takes several weeks to complete. The work should proceed as follows if you can get a contractor to quickly arrange for the hiring of laborers and tradespeople and maintain good weather throughout the duration of your project:

Week 1

The scaffolding must be erected first. On-site gathering of the job’s materials will take place. During this week, the roof will be opened up too.

Week 2

If the roof structure needs changing, this will be worked on next. If more support is required, it will be worked on too. The windows will go in now for a roof light conversion. The dormer will be built for a dormer conversion thereafter.

Week 3

This week will see the completion of the exterior work. The roof will have any construction completed, the tiles replaced, and the roof finished. Roof insulation will also be installed if requested. The interior of the loft will be prepared for any necessary plumbing and electrical work.

Week 4

The installation of all windows that need fitting will take place. Any necessary ventilation will be installed along with the floor. Both the internal walls and the plasterboard will be installed.

Week 5

At this point, the staircase will be installed. It can be installed simultaneously with the installation of a bathroom. You can anticipate the completion of the electrics during this week. The doors will be installed, the plaster will be skimmed, and the skirting will be fixed by the end of the week.

Week 6

Any unfinished tasks will be finished this week. The decorating, if it is your contractor’s responsibility, will take place this week. Throughout this week, the scaffolding will also be taken down.

This schedule depicts the ideal scenario, allowing for the least amount of time for each action to be taken while assuming no delays.

Dormer Loft Conversion Ideas

If you’re running low on dormer loft conversion ideas, take a look at the following:

  • Dormer loft bedroom. One of the most common uses for dormer loft conversions is for bedrooms. You can give your family more space if you have a new place to sleep, especially if your children currently share a room.
  • Dormer ensuite. Sometimes the regular floor plan of your property leaves you without enough room for en suites. However, dormer extensions give you the flexibility to add a bathroom right onto the bedroom.
  • Peaceful escape. Finally, you may want a space in your home where you can get away from it all. An L-shaped dormer loft conversion gives you an elegant space for sofa, ottomans, rugs and furniture.

Types of Dormer Loft Conversion

The best dormer loft conversion idea for your home will depend on the style of your existing roof, the type of house (terraced, semi-detached, or detached), and other factors.

Flat Dormer Roof

A straightforward addition that can be made to the front or back of the loft is the flat roof dormer loft conversion. The roofing materials used for this type are generally felt or single ply making it a cheaper option compared to a pitched dormer roof. Additionally, flat roofs can last for around 10 – 15 years.

It offers a relatively easy way to increase the loft’s usable space while also raising head height and letting in a lot of natural light through the dormer windows.

The shed roof dormer loft conversion is comparable to the flat roof option, but because of its slightly sloping roof, it may be built from different materials and is typically better suited for homes with gable roofs.

Pitched Dormer Roof

When the height of the existing roof is sufficient to support one, a pitched roof dormer loft conversion is a popular option. Due to the numerous internal angles that this style of loft conversion creates, it is typically regarded as one of the most aesthetically pleasing designs.

The roofing materials used here are either slate or tiled making it a slightly more expensive option compared to a flat roof.

Depending on the budget and your requirements, pitched roofing might seem like a better option for the long term.

Gable-Fronted Dormer

A dog-house dormer is another name for the gable-fronted dormer loft conversion.

This is a more complicated solution that involves building a new sloping roof section toward the new gable end and extending the gable wall upward to meet the existing ridgeline.

L-Shaped Dormer

A dog leg dormer or L-shaped dormer loft conversion consists of two dormers that are attached at an angle to one another. This can be a great way to add as much space as you can, with good head height as well, if you have the right kind of property.

This kind of loft conversion is typically used to create multiple rooms, which helps you make the most of the space in your house.

Hipped Roof Dormer

A conversion with a hipped roof and a dormer loft has roofs that slope on all three sides of the building.

This is frequently an attractive appearance, especially for larger properties. However, compared to a flat roof dormer, this style of dormer construction leaves less usable space in the new loft.

Benefits of a Dormer Loft Conversion

Make sure to weigh the advantages that a loft conversion can bring to your home as you weigh the costs.

Add Value to Your House

A loft conversion is regarded as one of the best ways to increase the value of your house, boosting it by an average of 22%.

It is crucial to conduct some preliminary research if your goal is to raise the value of your property. The price of homes has a cap in the majority of areas. For instance, houses in your area could sell for a maximum of £350,000.

Spending more than £30,000 on your loft conversion makes no sense if you spent £320,000 on your house. The value of your home won’t rise further if you spend more than that. So be sure to conduct some research to assist you in balancing your budget.

Energy Efficient

Insulation must be a part of your loft conversion per building regulations. Although it costs more, doing this will make your home more energy-efficient, which frequently results in significant savings on heating costs for you and your family.

Avoid the Cost of Moving

If you have thought about leaving your current home because of a lack of space, take a closer look at a loft conversion with a dormer.

They may be able to provide you with a solution for getting the extra space you require without having to pay for it or undergo the stress of moving.

Adding Natural Light

The ideal way to increase natural light in your home and frequently make it feel larger is to add more windows, especially to the roof.

Choose the right contractor to work with for dormer loft conversion

To ensure you work with the right contractor for a dormer loft conversion, make sure you obtain multiple quotes from different contractors. At SPS Roofing, we offer free quotations customised to your requirements.

It’s also a good idea to hire locally. So if your property is located in and around Exeter & Devon, do get in touch with us. We will be more than happy to provide a free consultation on the best course of action to take.

Looking For A Qualified Roofing Company?

SPS Roofing Ltd is a highly rated roofing company based in Exeter operating across Devon and South West England including Somerset, Cornwall, Wiltshire, Gloucestershire and Dorset.