Everything you need to know about rooflight loft conversions

A rooflight loft conversion is a type of loft conversion that is built into the existing roofline. Rooflights are installed on the roofline, converting a loft space into a usable room. Pitched rooflights are installed within the existing roof to add light and ventilation to the loft, creating a usable living space. 

Rooflight loft conversions are the most straightforward method of loft conversion, as they rarely require planning permission and are the most cost-effective choice due to the fact that there are no structural changes. 

Rooflight loft conversions work by adapting a loft space into a workable room without any structural changes or extensions. This is achieved by altering the roof structure to create openings to install the rooflights. The roof is then further strengthened using joists to carry the additional weight. Timber trimmers are also used for the roof structure. The additional timber supports the loaded weight of the rooflight, transferring the additional weight from the rafters that have been cut away to install the rooflight. 

Rooflight loft conversions are a popular and straightforward way of converting a loft space into a working living space. If you are looking for a cost-effective way to convert your loft, and do not want to change the structure of your roof, then a rooflight loft conversion is a perfect choice. They require less building work compared to other types of loft conversion such as dormers, and you will keep costs down as you do not need to pay for planning permission fees or additional building materials and labour costs. The main outgoings will be to pay for the rooflight and the rooflight installation.


Feeling inspired? Take a look at  our case studies to learn more about how rooflights can transform your home. 

What types of rooflight can be installed in my loft conversion?

Rooflight loft conversions will need pitched rooflights that will align with the existing roofline. There are several different types of pitched rooflights, including flush conservation rooflights and contemporary pitched rooflights. 

How much does a rooflight loft conversion cost? 

The final cost of your rooflight loft conversion will be dependent on the size of the space you are working with. You will also need to consider:

Planning permission fees - if you need planning permission

Development rights

Party wall agreement - if the conversion affects a neighbouring property

Building control fees - to cover costs associated with building regulation approval. This includes building surveyor costs, which includes a site inspection and completion certificate upon final inspection. 

Structural engineer fees - to cover the costs of analysing the project design and site for suitability and safety of any structural components of the conversion 

Architect fees - if you hire an architect to assist with the design and drawings that are put out to tender 

Rooflight loft conversions are the cheapest type of loft conversion. On average they cost 25% cheaper than other types of loft conversion such as a dormer conversion, hip to gable conversion, or mansard conversion. They are cost-effective because rooflight loft conversions require no structural change to the property. 

A report by On The Market stated that loft conversions can add up to 22% to the value of your home, making them a fantastic investment. 

Do I need an architect for my rooflight loft conversion?


It is not required to have an architect for your rooflight loft conversion but it can be very beneficial. An architect can help bring your initial concepts to life and discuss initial ideas and design plans to ensure you are getting the most out of your loft conversion.

An architect can use their expertise to advise and suggest the best way to plan a rooflight loft conversion to ensure you are using the space as efficiently as possible, to keep costs down and maximise the value and outcome of the project. Architects can also provide professional drawings that then go out to tender, and can help ensure all aspects of the build are following building regulations and guidelines. 

Rooflight loft conversions and building regulations

Building regulations approval will always be needed when converting a loft. Although a rooflight loft conversion may not require planning permission, building regulations must be adhered to in order for the conversion to go ahead. In order to receive a completion certificate, which is needed before work begins, a building control surveyor will come to the property to inspect the site and proposed project plans. Any type of loft conversion must adhere to the following sections of the Building Regulations Act of 2010. It is your responsibility, before any work is undertaken, to check if you need planning permission.

This covers matters such as the thermal efficiency of the project, as well as the U- Value on completion. U-Value is the term given to the thermal efficiency of a property; specifically,  the amount of heat that can transfer in and out of the property.  You can read more about building regulations for rooflights here. 

This section refers to any issues regarding risk of falls, collisions and impact, as well as the requirement of 2m headroom for escape routes.

These sections cover matters related to fire and electrical safety.

Do I need planning permission for my rooflight loft conversion? 

It is your responsibility, before any work is undertaken, to check if you need planning permission. In many cases you do not need planning permission although there may be some restrictions depending on your exact project specifications. Some loft conversions will require planning permission, however, as a rooflight loft conversion doesn’t extend or convert the main structure of a property, in many cases you will likely not need it. Please check with your local planning office before undertaking any work.

You won’t need planning permission for your rooflight loft conversion as long as:

  • Any roof windows installed do not protrude more than 150 mm (1.5m) above an existing roof plane 
  • Any side-facing windows feature obscure glazing for privacy reasons and do not open more than 1.7m 
  • There are no alterations to the existing roof structure that is higher than the current highest part of the roof 

Rooflight loft conversions are also a very popular choice for conservation areas, as some listed and heritage buildings have restrictions about the types of extensions and conversions that are allowed. Listed or heritage buildings will require any changes on the outside to match aesthetically with the houses in the surrounding area. It is for this reason why flush conservation rooflights are needed.  It is possible to carry out a rooflight loft conversion with conservation rooflights, so that the project does not alter the exterior of the building in any way. It is your responsibility, before any work is undertaken, to check if you need planning permission.

Read our guide on conservation rooflights here

Can I get a loft conversion?

You can only get a loft conversion if you have the required amount of headroom in your property. You will be eligible for a loft conversion only if the loft has 2.2m of usable space. This allows an acceptable amount of head height, giving room to safely build up the floor and create a workable living space. 

What are the benefits of a rooflight loft conversion?

  • Good for conservation areas
  • May not require planning permission 
  • Popular choice because it doesn’t impact the main structure of the building / extend the building - uses what you’ve got 
  • More cost-effective than other conversions 

How long does a rooflight loft conversion take? 

A rooflight loft conversion project lead time will depend on the size of the loft and the exact design specifications of the build. Consult with a design architect or building contractor as early as possible to gain an estimation of how long it will take. 

What to consider before getting a rooflight loft conversion

Be realistic about the space you have to work with. Is it large enough to be a bedroom, or will it work perfectly as a home office? Deciding how you will use the space will help the design project to create a bespoke build that works as closely as possible to your requirements. 

Have an idea of your budget before you start building work. Understanding how much everything costs before you start is vital, in order to be sure you can afford to go ahead with the conversion. 

Who do I contact for a rooflight loft conversion?

Ask friends and family for recommendations of an experienced builder, loft conversion company or architect. You can also conduct your own research to find a local company in your area. Get in contact and get the conversation started about what you can expect to pay for your potential project.


Keen to get started with your rooflight loft conversion? You can get inspired by checking out our recent case studies or explore our entire range of rooflights and skylights. If you want to learn more, feel free to get in touch today on 01993 833155 and make an enquiry. 

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