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 Loft Conversions

02071 014730

02071 014730

Permitted Development Loft Conversions

Class B - additions to the roof of the dwelling house.


Class B permitted development loft conversions provide you with excellent space for new Bedrooms, Bathrooms, En-Suites and Storage. At, your personal designer will create intelligent designs to optimise your loft space!

​Permitted Development allows home owners to extend into the loft of their property, and in most instances, achieve exactly what they are looking for from their project without the need for planning permission. The size of conversion is set by the Government through their Permitted Development Technical Guidance and we have specialised in optimising these regulations to deliver your perfect loft conversion. And even if we discover that your desired conversion may go beyond the regulations, there is nowhere better to go as we have unparalleled planning knowledge in loft conversions. Still looking for more information on what is permitted development? Click here to view our dedicated page.

Our Simple Fixed Fee covers everything you require for your loft conversion 

We have a straight-forward, hassle-free architectural process that guarantees the of your permitted development loft conversion. 

Stage 1 - Measured survey & existing architectural plans drawn up. 

Stage 2 - Personal designer to draw your ideas to life. 

Stage 3 - Unlimited design revisions to perfect your loft conversion. Utilising our expert planning knowledge, we will complete your application and work with your local planning authority to achieve planning. 

Permitted Development is here for all your loft conversion needs!


With years of experience in permitted development loft conversions, we're more than equipped to handle any project. The kind of certificate you will need to obtain is called a Lawful Development Certificate. For loft conversions, there is no prior approval or larger home extension scheme. This is because the permitted development loft conversion allowance is very generous.

Lawful Development Certificates:

Lawful development certificates allow permitted development loft conversions on a terraced house, house up to an additional 40 metres cubed on top of the original loft space. For detached houses, semi-detached houses and bungalows, you can create up to 50 metres cubed on top of the original loft space. This additional space is created from the addition of a dormer (Extension out of the existing roof). In most instances, the dormer can span the full width of the rear of the property providing ample space to deliver exactly what you are looking to achieve. 

Permitted Development loft conversions under a lawful development certificate are great! Because the council can not refuse the application and neither can your neighbours, providing you a 100% chance of approval. Unlike the traditional planning permission route which can take longer and have limited success. 


Permitted Development Loft Conversion Rules:

The permitted development loft conversion rules are written as what is not permitted & what is permitted. The rules created by government are;

Class B additions to the roof are not permitted if:

(A) Permission to use the dwellinghouse as a dwellinghouse has been granted only by virtue of Class G, M, MA, N, P,  PA or Q of Part 3 of this Schedule (changes of use).

(B) Any part of the dwellinghouse would, as a result of the works, exceed the height of the highest part of the existing roof.

(C) Any part of the dwellinghouse would, as a result of the works, extend beyond the plane of any existing roof slope which forms the principal elevation of the dwellinghouse and fronts a highway.

(D) The cubic content of the resulting roof space would exceed the cubic content of the original roof space by more than,

             (i) 40 cubic metres in the case of a terrace house, or

             (ii) 50 cubic metres in any other case.

(E) It would consist of or include;

             (i) The construction or provision of a verandah, balcony or raised platform, or

             (ii) The installation, alteration or replacement of a chimney, flue or soil and vent pipe.

(F) The dwellinghouse is on article 2(3) land.


(G) The dwellinghouse is built under Part 20 of this Schedule (construction of new dwellinghouses).

(H) The existing dwellinghouse has been enlarged in reliance on the permission granted by Class AA (enlargement of a dwellinghouse by construction of additional storeys).

(Extra Info) Development is permitted by Class B subject to the following conditions:

(A) The materials used in any exterior work must be of a similar appearance to those used in the construction of the exterior of the existing dwellinghouse

(B) The enlargement must be constructed so that

            (i) Other than in the case of a hip-to-gable enlargement or an enlargement which joins the original                    roof to the roof of a rear or side extension

                                 (aa) The eaves of the original roof are maintained or reinstated; and

                                 (bb) The edge of the enlargement closest to the eaves of the original roof is, so far as                                               practicable, not less than 0.2 metres from the eaves, measured along the roof                                                   slope from the outside edge of the eaves.

             (ii) Other than in the case of an enlargement which joins the original roof to the roof of a rear or                          side extension, no part of the enlargement extends beyond the outside face of any external wall                    of the original dwellinghouse.

(C) Any window inserted on a wall or roof slope forming a side elevation of the dwellinghouse must be;

             (i) Obscure-glazed, and

             (ii) Non-opening unless the parts of the window which can be opened are more than 1.7 metres                          above the floor of the room in which the window is installed.

How Permitted will bring your loft conversion into reality

We undertake a full measured survey of your existing house to enable us to plan your home reliably and cost effectively. We produce as existing drawings of your property which are required in your Lawful Development Certificate.

Your personal designer will undertake a detailed design brief with you where we will discover exactly what you are looking to achieve from your loft conversion. They will design two concepts from your brief and create bespoke architectural drawings tailored to you.


We will provide you with the highest quality floor plans, elevations, and 3D views as seen in our videos. We will also provide rendered images that will give you a full understanding of the possible materials and finishes. You'll be able to see exactly what it will look like in real life before it is built!

You will then work with your personal designer to tailor the concepts and create your perfect design!

We understand that this process is difficult and decisions are hard. However, your personal designer will be there to help every step of the way and will draw recommendations from their architectural and local planning experience to make the design process seamless. ​Unlimited drawing revisions will enable you to create your perfect extension.


Once the design has been achieved, we will obtain a Lawful Development Certificate, or if it is required planning permission. You are now ready to build!


Legally, you must ensure that your project complies with building regulations which is a statutory requirement.

Our building regulation and structural drawings cover everything from the foundations all the way up to fire regulations, thermal efficiency, and even sound insulation. 

We have vetted chartered structural engineers, building regulation specialists, party wall surveyors, drainage experts, land surveyors, and all other potential third party specialists that could be required in the signing off of your project.

This process will leave you in the best possible position going into the construction phase, providing your builder and your local authority's building inspector with everything they require. 

We hope you are as excited to start your project today as we are! Please fill out our Contact Us form below so we can start your project as soon as possible. Or feel free to call us where you can speak to one of our specialists for any information you require. 

Permitted Development Government Guidance

Whilst we know the permitted development loft conversion rules inside-out, it might be helpful to familiarise yourself with it too.

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