A Guide to Loft Conversion

Guide to Loft Conversion


Loft conversion is a common practice in creating additional living space. Apart from the advantage of having extra space, loft conversions can also add value to homes. But before starting any loft conversion work, there are certain important regulations that you need to check. In this guide for loft conversion, you’ll determine whether you need planning permission and which building regulations you need to comply with.

Planning Permission on Loft Conversion

Most loft conversions do not require planning permission because it falls under permitted development rights. However, you need to adhere to several parameters. If you exceed the limits or your home is in a conservation area, you need to apply for planning permission. Before starting work, always check with your local planning office.

You don’t need planning permission if you follow the following parameters:

  • Volume of additional space must not exceed 40 cubic metres for terraced houses and 50 cubic metres for detached and semi-detached houses. 
  • No extension should exceed the plane of the existing roof slope at the principal elevation or front of the house. 
  • Extension should not be higher than the highest part of the roof.
  • Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the original eaves.
  • Materials should be similar in appearance of the existing house
  • No verandas, balconies or raised platforms.
  • If the windows face the side, it needs to be obscure glazed. It should also be 1.7 metres above the floor. 
  • The roof enlargement cannot overhang the outer face of the wall of the original house. 

If you own a flat or maisonette, please know that there is a separate regulation for this housing type. Also, Restricted zones and other designated areas such as national parks or heritage sites do not allow roof extensions.

Loft Conversion Building Regulations

Having no planning permission requirements does not mean you don’t need to follow building regulations. You may refer to topParts L, K, B and P of the Building Regulations. You need to follow specific building regulations: 

Building Regulations Pack
  1. Loft Conversion Handbook

The book is an easy-to-use handbook providing architects and builders with current guidance on managing loft conversions and ensuring they comply with the Building Regulations. This is an essential read for anyone looking for a guide which simplifies the building regulations process and offers solutions, where applicable, to achieve minimum, good practice and advanced construction standards.

Floors and Junctions

Building a loft will require new floors, beams and junctions. Your existing and new structural elements must be able to carry the load of your new loft. Consult a professional if you are unsure about this.

  1. Aluminium Vapor Barrier


If you are thinking of converting your loft, this Aluminium vapor barrier could be very useful for insulating and keeping your loft in your desirable temperature. This Aluminium vapor can be used as a vapor barrier under plasterboard if used in combination with immediate roof cooking, the membrane ensures optimum ambient conditions in attic rooms. 


Building new walls to support any existing or new roofs where existing supports have been removed. You also need to ensure that there is enough sound insulation between rooms. 

  1. Insulating Paint


This advanced energy saving paint, prevents condensation problems like mold, blistering, discoloration, staining, peeling of wall paper, while preventing heat loss. Perfect for making that slight difference to keeping your loft in tolerable temperature conditions


Any loft requiring new windows/dormers will need to follow certain regulations. 

  1. Skylight Window


If you are looking for an effective way to bring in natural light to your loft, skylights are the best option. Skylights are windows placed on the roof. This high quality rooflight system will allow continuous flow of fresh air into your home.


Roof enlargements due to loft conversion required to follow roof building regulations. Including compliant roof insulation. 

  1. Measuring Tape 


Before you plan on converting your loft it is advisable that you carry out measurements so that you can visualize if you can create your dream loft. You can use this measuring tape to determine the height and size of your loft conversion and to ensure there is sufficient space before purchasing materials and renovating it.  

You may also refer to our Ultimate Building Regulations Pack for complete building regs specifications and drawings. For areas protected under the law (Conservation, Heritage, Protected Species) contact your local planning office.

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