What Are The Building Regulations for Loft Conversion?

What Are The Building Regulations for Loft Conversion?

Converting the dead space in your attic, and turning that dumping site into a much-needed living space is an excellent way to optimise your home and increase your property’s value. However, with all the talk about the benefit of having your loft converted, an Achilles heel for most homeowners is understanding the regulations and the planning permission to follow to have their Loft Conversion approved.

In this article, you will learn the different types of loft conversion, the challenges associated with a loft conversion, which conversion needs planning permission, the building regulations, and as a bonus, the cost of converting your loft. At the end of reading this article, you will become familiar with everything (well almost everything) about a loft conversion project and make smart decisions when the need arises to choose the loft conversion type that suits you.

Types of Loft Conversion

A loft conversion is converting your attic or a dead space where you have turned into a dumping site for storing the family heirloom into a functional, living area. Unlike home extensions that eat up valuable outside spaces, loft conversion lets you keep valuable outer space, making it an excellent and stress-free way of adding additional living space to your home.

The benefits of loft conversion are humongous, and some of them are;

  • Increases the value of your property by more than 15%
  • Remove the emotional turmoil of moving house
  • A cheaper alternative to moving house
  • Add natural light
  • Reduce your energy bill
  • Keep valuable outside space
  • Innovative and multi-functional
  • Tax breaks

Although the average loft conversion cost is roughly £45,000, this amount is not straightforward as there are other factors such as size, finish, quality, and design choice that impact this price. In the UK, there are 4 common Types Of Loft Conversion, and these are; Dormer conversion, Mansard conversion, Hip to Gable conversion, Velux conversion.

1. Dormer Loft Conversion

Mansard Loft Conversion

This is by far the most popular type of loft conversion. This conversion vertically extends the slope of the roof, thereby creating a box shape. There are no dramatic changes with a simple flat foot dormer, allowing the installation of conventional windows.


  • Adds useful headroom
  • Creates a massive amount of internal space
  • Good light and ventilation
  • Suitable for most UK homes
  • Falls under permitted development


  • It is not an aesthetically appealing choice

2. Mansard Loft Conversion

Hip to Gable Loft Conversion

Typically found at the rear of the house, a Mansard loft conversion is built by raising the party wall shared with your neighbour. Although the roof remains flat, one outer wall slopes inward gently.


  • More aesthetically appealing than a dormer
  • Blends well into older properties
  • More headroom than any other type of conversion
  • Allows light to flood your loft


  • Construction time is long
  • Eye-popping price
  • Always requires planning permission

3. Hip to Gable Loft Conversion

Ideal for terrace and detached homes, a hip to gable loft conversion straightens an inwardly slanted roof to create a vertical wall. This little transformation makes a significant difference to the living space, and it is a rising trend in the UK


  • No planning permission
  • Can be combined with a rear dormer loft for optimal space
  • Suitable for bungalows and chalets
  • Aesthetically appealing
  • It creates space without disrupting the natural feel of the house structure blends in well with the existing home


  • Not suitable for mid-terrace homes
  • More expensive than a dormer loft
  • Can feel imbalanced if your neighbor hasn’t had one

4. Velux Loft Conversion

When Converting My Loft

Also known as a roof light loft conversion, if your loft already has enough headroom available, then the best choice is a Velux conversion. By far the easiest, fastest and less invasive way to convert your loft or attic, the Velux loft conversion is very cost-effective as the roof remains unchanged. All that needs to be done is to add windows to let more light in.


  • Almost 25% cheaper than other types of conversion
  • More likely to be approved in conservation areas
  • Plenty of room for storage if you get creative with your eaves
  • Less disruptive
  • Natural light means less money spent on electric bills


  • It doesn’t create any space
  • May require planning permission if windows are at the front
  • Can only be done if you already have enough headroom

What Challenges Am I Bound to Face When Converting My Loft?

Converting your attic into a functional living space is by no means a small feat, and so, because of the scope of work to be done, there are bound to be problems. Knowing what these challenges are, gives you an idea of what to look out for and plan for their eventualities.

Some of these challenges are;

  • Living with The Disruption
  • The Frustration of Finding the Right Service Provider
  • Overspending
  • Fixtures and Furniture That Don’t Fit
  • Missing Planning Permission
  • Party Wall Disagreement
  • The Problem of Asbestos

What are the Building Regulations I Need to Know?

Whether you need planning permission for your loft conversion project or not, you are under an obligation to follow the relevant building regulations. Building regulations are critical because they ensure that any alteration is structurally stable and built to last with stairs and fire escapes planned and installed correctly. There are specific regulations that you need to be aware of when planning your loft conversion (any specialist contractor is fully aware of these guidelines);

Creating a Storage Space – if the purpose for converting your loft is to turn it into a storage space, you may need to seek building regulation approval. This is because the timber joists that act as the “floor” of the loft are not designed to support any significant weight, meaning that excessive weight can lead them beyond their capacity. So, you need building regulation to ensure their safety.

Creating a Functional-living Space – if the goal is to create a live-in space, you need to seek building regulation approval as part of your home. This is because loft conversions usually require a range of changes to be made which can affect the original structural integrity of the building so that both the house and its occupants are not at risk

What Is The Summary of the Building Regulation?

The basic gist of the building regulations are;

  • Where new floor joists are required, they must be supported by an existing wall that goes down to the foundation of the house
  • The roof will need to be reinforced when new timbers are installed because of the opening cut in the existing rafters when the roof windows were installed.
  • Installing new floor joists that are larger than the existing ones to take on the new weight.
  • Compulsory staircase to act as a fire escape.
  • Where space is a challenge, it is possible to install a space-saving staircase, but never a retractable ladder
  • The building regulations for a loft conversion mandates that you insulate your loft

Generally, building regulations will determine almost everything about your loft conversion. From material layout, staircase, almost everything.

Loft Conversion Stairs Regulations

Loft Conversion Stairs Regulations.

Before you think about your stairs’ positioning, the first thing you want to find out is if the rules allow you to have the kind of design you have in mind. Consider the following regulations for your loft conversion stairs;

  • There must be a maximum steepness pitch of 45 degrees.
  • There must be a fixed staircase to provide safe access to and from the loft.
  • There must be a minimum headroom height of 1.9m.
  • If there is a drop of more than 600mm, there must be handrails provided on the staircase.
  • The risers must all be equal.
  • For single rooms, space saver stairs with handrails on both sides.

What Other Regulations or Guidelines Should I be aware of?

Planning Permission

For the most part, you won’t need planning permission for loft conversion because in most cases, loft conversions fall under permitted development. However, to be safe, you should follow these guidelines (don’t worry though, a contractor worth his onions will know a lot about this);

  • The new loft space should not be larger than 40 cubic metres for terraced houses, and 50 cubic metres for detached and semi-detached houses.
  • The loft conversion doesn’t extend beyond the plane of the existing roof slope at the front of the house (principle elevation)
  • The loft conversion does not extend higher than the highest part of the existing roof.
  • The loft conversion does not include any verandas, balconies, or raised platform
  • The loft conversion is made using the same material similar in appearance to the rest of the house
  • Any side-facing window must be obscured-glazed
  • The roof extension is set back at least 20cm from the original eaves except for the hip-to-gable loft conversion
  • The loft conversion does not overhang the original walls
  • Your home is not located in certain designated areas, including national parks, areas of outstanding natural beauty, conservation areas, and world heritage sites.

Where any loft conversion exceeds these limits and conditions stated above, you need to apply for planning permission from your local authority

Third-Party Wall Agreement

It depends on the type of loft conversion and its effect on the shared wall with your neighbour. Your contractor should be able to advise you on this. If you do need one, it is recommended that you speak with your neighbour two months before the work is to begin.

Your neighbour has two responses, to agree or disagree. Where there is a dissent, you need to get an agreement drawn that will state the conditions and responsibility for any damage to the party wall. It will be more comfortable and cheaper to discuss with your neighbour and come to a documented amicable resolution.


Having the right partner can make your loft project a piece of cake, and that is what TEL Construction achieves for our clients. With in-depth knowledge of the building regulations, we help homeowners achieve their dream of providing their loved ones with the stability needed to thrive and create functional live-in spaces that increase their properties’ value.