How to Build a Roof Dormer in Manchester: A Simple Guide

In this guide, we will guide you through the main things to know in order to build your roof dormer.

Dormer roof extension architect
Credit: @Plusrooms

As with any construction project, it is extremely important that roof dormers are designed, planned and built correctly. In many cases roof dormers will need careful layouts to make them worth doing in the first place and may also require planning permission.

This article will teach you how to build a roof dormer, with step-by-step instructions on what materials you'll need and the tools required. It's never been easier!

What is a Roof Dormer?

A roof dormer is a structure that projects from the roof of a building, with either a rectangular or gabled roof. It is used to provide extra space in roof spaces, such as an attic. 

Image credit @Curbed

Modern roof dormer

Why Build a Roof Dormer?

There are many reasons why you might want to build a roof dormer. Perhaps you need extra space for an office or a child's bedroom. Maybe you want to build roof dormers to give your home a modern look and feel, as roof dormers are very popular in new homes and renovations alike.

There are two main types of roof dormers - the gabled roof dormer and the rectangular roof dormer.

1. Gabled Roof Dormer:

A gable roof dormer is the most common type, and it is characterised by its triangular shape. The roof slopes down towards the front and back of the building, with a gable roof at the top.

2. Rectangular Roof Dormer:

A rectangular roof dormer is less common, but it can be a great option if you want to add more space to a room that has unusual or awkward dimensions. It is just like its name suggests - a rectangular structure with straight rooflines on all four sides.

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Wooden roof dormer architect

What are the Benefits of Having Roof Dormer in Manchester?

Having roof dormers can have many benefits for your home, including:

Extra space - roof dormers are a great way to increase the size of your house without having to move or add an extension. This is especially useful if you live in an area where property prices are high and land very scarce.

A better insulated roof - roof dormers can help to improve the insulation of your roof, which in turn will keep your home warmer in winter and cooler in summer.

Adds value to your home - by adding a roof dormer to your home, you'll be increasing its value significantly. This is especially true if you live in an area where there are not many homes with roof dormers.

Makes a modern statement - roof dormers can make your home look very stylish and up to date, as they are a popular addition in new homes or renovations alike. They also provide an attractive feature that many people enjoy looking at!

You can enjoy views out for above - Having an extra storey of height to view out of windows from can often give you excellent views which adds to the quality of the dormer space.

Image credit @Studio Octopi

Wooden interior

How Much Will It Cost?

The cost of roof dormers varies depending on the type of roof dormer you are looking to build, as well as its size. The average cost for a large roof dormer accommodating a master bedroom and ensuite will cost around £35,000 - although prices can be higher depending on location, size and finishes for your dormer.

Below we have provided a calculator for you to make estimated costs for your planning, you can use this in order to get the estimated construction costs based on the size of your dormer!

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Dormer roof modern design

Roof Dormer Construction Calculator

  • Construction Cost incl. VAT
  • VAT 20% Excluding VAT
  • Professional Fees Based on average complexity
  • Initial Consultation

How to Build a Roof Dormer: Step-by-Step Instructions

Here are the step-by-step instructions for how to build a roof dormer:

Step 1: Note down all the requirements for your dormer

Before going further, try to note down the main things your new roof dormer should be doing for you.

This could be a new bedroom space, a bathroom or even a games room. If you are unsure how to best use the new space your creating or need ideas, we offer free advice workshops to make the process easier.

Step 2: Design your dormer / have your dormer designed

Once you have a detailed set of requirements for your project, you are now ready to start drawing and designing. Roof dormer spaces can be difficult to design as it depends on the correct staircase placement and using the highest space within your roof.

It is recommended to have your project designed to be planning permission friendly and easy to build from the beginning, an architect can help you do this alongside other services.

Step 3: Apply for planning permission (if you need it)

Some many properties in Manchester and across the UK, it will be possible to build a roof dormer through permitted development, meaning you will not require planning permission.

You will need to check exactly what size and visual style will be allowed and make sure your design complies with this, otherwise you will need planning permission. Either way, we can advise you on which option is best for you by reaching out to us.

If you live within areas such as a conservation area, green belt land or you have a listed building. You can find additional information with our guides or by reaching out to us for free advice.

Step 4: Make sure your design is checked.

Before you start any construction, it is recommended that your designs are checked by a building control officer.

These can be found within your local council or through a private trading company and will advise you on any measures you may require to make the design UK building regulations compliant.

This can include, structural calculations, fire protection and thermal efficiency and will depend on your building and project. If you would like further guidance, our experience with building regulation matters can help you plan ahead to avoid problems further down the road.

Step 5: Build your dormer / have your dormer built

Once the items above have been clarified, you are ready to build!

If you are building yourself, it is important to do a full quantity check for the items you need to purchase and each task that needs to be done within the build, this will help you plan for time frames and calculate the total costs you can expect.

If you are looking to have you dormer built by a builder, be sure to attract multiple quotations and vet them accordingly. 


In conclusion, this guide will help you plan the journey of gaining a roof dormer in Manchester easily and stress-free. Construction projects always benefit for proper planning and clearing any red tape exercises BEFORE you start building on-site. 

Happy Building!

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Metal roof dormer design

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