Extension Cost

Projects can be designed and built to meet a specific financial budget. For instance, a domestic project from experience would cost in the region of £1,200 – £1,500 per m2. This reflects recent price increases over the last few years. If you’re developing an extension within London and some parts of the South East, these figures can increase to £1,500 – 2,000 per m2.

In addition to this, you will need to include approximately 10-15% for professional fees (architect, planning application, building regulations, structural engineer)

And let’s not forget to include 20% VAT that will need to be included on top of your total fees.

So how do the fees increase if you decide on a double storey extension? The general rule of thumb you can add 50% extra to the build cost of a single storey extension.

For instance

£30,000 for a single storey extension

Add 50% of the single storey fee for a double storey extension = £15,000

Double storey extension = £45,000

In addition to the fees would be specialist products ie bi-fold doors, roof lights or lanterns, underfloor heating etc.

What About my Kitchen and Bathroom? 

The above costs generally will not allow for your kitchen and bathroom costs or flooring and floor and walls finishes.

We would normally advise allowing between £3000 – £5,000 for a bathroom and £10,000 for a kitchen (again, completely depends on your specification, but this should get you a lower-midrange kitchen with appliances)

Looking for a FREE consultation? We offer 30 minutes at no cost to you. Call us today.

What is planning permission and will I need it?

Generally, most projects require Planning Permission and also Building Regulations approval before works can commence on site. Each project differs in requirements i.e, is your property in a conservation area or is your property Listed? If so Listed Building Consent will be required and in some cases, conservation area consent is required.

Permitted development rights are available however these are dependent on a number of factor such as location, size of the site, size of the proposal, has there been any other development on site

I always recommend Informal pre-application discussions with planning prior to any formal submissions, they greatly help a project in the initial stages of development. Planning are there to help and being aware of a forthcoming project is useful in that respect.

How long does it take to get planning permission?

Usually minor projects have a set timescale of 8 weeks from the date the local planning department have validated the application. For major developments, this can take 13 weeks. However, this also depends on the workload and staffing levels at the local authority.  Over recent years we have noticed various departments for planning requesting extensions of time to make decisions on applications.

What is building control and how long does it take?

The Building Regulations are concerned with the constructional details of buildings and set down minimum standards to safeguard the health and safety of persons in and around buildings; conserve fuel and power and provide facilities for disabled people. They are applied by all local authorities in England and Wales and therefore apply on a national basis. However, since recent changes in the law approved inspectors or private building control companies have taken over a large sector of the market providing a more customer-based efficient service.

Building regulation approval will normally take between 2-4 weeks depending on the type and size of project. Once your plans have been approved by building control they will carry out a series of site visits to check the completion of works at various stages. On completion of the works building control will carry out their final check and issue a final completion certificate providing all the works comply and the necessary certificates have been completed such as Gas Safe and Electrical installation.

If you’re planning a project this Spring / Summer call us today for a FREE 30-minute consultation 02476 629192 or email info@liteboxarchitecture.co.uk

Architectural Designer Fees

Architectural designer fees are calculated in three ways: a percentage basis; a lump-sum basis; or time charged by agreement. Expenses may be included in the agreed fee or charged separately.

Percentage basis

In this method, fees are conveyed as a percentage of the total construction cost. Both client and architectural designer need to establish the services to be provided before fees can be estimated including the approximate construction budget and the nature of the work.

Lump-sum basis

Best used where the scope of the work proposed can be clearly defined from the outset. It is important to define the parameters of Architectural designer services including time, project size and cost where applicable, so that if these are varied more than an agreed amount, the lump sum itself may be varied.

Time-charged basis

This basis is best used where the scope of work cannot be reasonably foreseen or where services cannot be related to the amount of construction. It may be wise to set an upper limit on fees to be incurred, perhaps on a staged basis.

As a very rough guideline, architectural designer fees for a domestic project could be anywhere in the region of 5-15% of the overall project budget, dependant on the factors set out above. The following figures are taken from independent annual fee survey, showing average fees relative to the whole project budget and include all of the project stages listed above:

  • £25K – 10.7%
  • £50K – 9.9%
  • £75K – 9.5%
  • £150K – 8.7%
  • £500K – 7.3%
  • £1M – 6.5%

If you’re planning a project this Spring / Summer call us today for a FREE 30-minute consultation 02476 629192 or email info@liteboxarchitecture.co.uk

A Client-Focused Service:

At LiteBox Architecture we focus on providing a service that extends well beyond producing a set of drawings. We aim to listen and identifying the needs and aspirations of our clients, we bring our specialist skills, knowledge and experience to your project.

Value for Money:

Not only can we provide value for money, but professional attention to detail that will achieve value through the most efficient use of space and careful selection of materials and finishes. Environmental sensitivity, energy efficiency and low running and maintenance costs can bring extra benefits to your project and long-term savings!

Freedom from Worry:

LiteBox Architecture can guide you through the complex procedures of planning permission and building regulations and monitor the builder’s programme of works through to completion of your project. We are also obliged to carry professional indemnity insurance – giving you peace of mind.


Whether you’re looking for tradition or innovation, boldness or understatement, we can lift your project out of the ordinary. Many people will offer to alter your building. It takes an architect to maximise its potential and to do it with flair, imagination and style.

A building project, whatever its scale, can be daunting, but the same basic criteria apply, be it a simple house extension or a large office development. When you use our services you are employing someone who has years of professional training and experience.


When you employ a designer, you’re paying for their knowledge, skill and experience – not just a set of drawings. Usually, the final drawings are produced relatively quickly at the end of a design process that involves discussion between client and professional. Sketch plans are drafted along the way and the ideas generated are either kept or rejected as the design progresses.

Whilst imagining a design, we are thinking about how it will be built, the structural implications, the Building Regulations that apply and the likely cost. If these things are not considered during the initial design they may present problems later on.

Most people appreciate that an architect’s ‘unique selling point’ is good design. But what does this mean? The role involves a lot more than simply ensuring that the end result looks great. A truly good design by an architect does a lot more than this. It means that the new rooms and spaces fit the lifestyle of the family living in the space, the detail of the construction has been well thought out, and the project is broadly within the budget that was agreed.

To achieve all these wonderful things requires expertise and skill, but also adequate time has to be spent by the designer on all stages of the project. This attention to detail is just as important for a house or extension as it is for a posh office development – arguably more important since there is an intimate relationship between a dwelling and its occupants that doesn’t apply to other types of building.

Let’s start your inspiring design today.

Project: Loft Conversion to Existing Mid Terrace 3 Bedroom House

This is the second instalment of our loft conversion case study and is the exciting part that follows the work undertaken by Oakland Mills week by week.

Week 1

Work starts on site and the scaffold is erected outside to allow a suitable working platform for this loft conversion. The dusty loft is cleaned and cleared of the original insulation to expose all areas of the loft.

Week 2

The fabricated structural steelwork arrives on site and is installed to create the skeleton framework for this loft conversion. Two new steel beams will be positioned above the existing ceiling joists and fixed on padstones into the existing party wall to the front and rear of the loft floor plan. A third beam will be installed under the existing ridge timber in order to support the existing roof and the new flat roof dormer. Timber inserts are fixed with the steel beam flanges and metal banding is fixed to support the existing ceiling joists once the original ceiling binder is removed.

Week 3

The builders have been fighting against the weather but have managed to strip the existing concrete roof tiles in preparation for the new dormer structure. The breathable roof felt will provide a much-needed dry working environment sheltered from the weather.

Next, the low-level stud walls are constructed on top of the steel floor beam and the new rafters are fixed alongside the existing rafters leaving a storage access hatch. The new floor joists are installed between the new steel floor beams and fixed into position using joist hangers. We can now start to see the basic shape of the loft room coming together.

The first hole in the internal ceiling as the builders break through the first opening into the landing area for access to materials.

Week 4

It’s a bright sunny day and time to open up the rear roof and start work constructing the large flat roof dormer. Quickly the external shelf of the dormer and flat roof decking is installed and the breathable felt is wrapped around the structure within the day to provide some external weatherproofing. The next day the rubber flat roof membrane is bonded to the flat roof decking and the dormer is completed with vertical tiles the façade.


Week 5

The existing roof structure is ready to be removed now the roof has been successfully supported and is now protected from the weather. Work can now begin on the internal areas of the loft conversion.

Quickly the loft conversion is insulated with a polyurethane rigid insulation board packed between the rafters allowing a 50m air gap above. The Velux roof lights are installed to the front elevation sloping roof allowing the natural daylight to flood the room, what a difference this makes to the once dark, dusty loft.

The work progresses, and the internal areas are fully insulated, stud walls are erected and the walls are boarded ready to be plastered.

The new UPVC windows are installed to the dormer and the en-suite springs to life although we are still waiting for the bathroom suite.

Week 6

The external flat roof dormer is now completed with the UPVC facia, soffit and guttering and the lead flashing is installed.

The big day finally arrives and the new timber staircase is installed allowing natural daylight to lighten up the existing dark landing area.

Week 7

The plasterers have arrived ready to give the loft room a nice smooth plaster finish. This will take approximately 14 days to sufficiently dry out before the walls can be applied with a backing coat painted finish.

Week 8

The scaffolding is gone and showcases the new rear elevation and the flat roof dormer.

The new bathroom suite has arrived and the plumber is busy fitting the suite whilst new tiles are fixed to the floor and walls. At last the en-suite is complete and looks great.

The plastering has dried out and the doors, skirting and electrics have been installed and the loft conversion is ready for the final decoration and new carpet.


After 8 weeks this loft conversion is finally complete within budget, and our clients are happy. The loft conversion looks fabulous and has created a large much needed bright bedroom. From this old dark and dusty loft to a bright and spacious bedroom with en-suite.

If you have a loft conversion or extension in mind, contact us at info@liteboxarchitecture.co.uk and let’s start designing your project today.

The long-anticipated 20% increase in planning fees on applications submitted in England has now come in to effect from 17thJanuary 2018.

The increase is the first since 2012 and will affect all applications where a fee is currently required to be paid to Local Planning Authorities (LPAs). In addition, the regulations introduce a fee of £96 for prior approval applications to permitted development rights that were introduced in April 2015 and April 2017. These include the rights for the installation of solar PV equipment on non-domestic buildings, the erection of click-and-collect facilities within the land area of a shop and the provision of temporary school buildings on vacant commercial land for state-funded schools. The new regulations also include provisions for LPAs to charge a fee in instances where permitted development rights have been removed either through Article 4 directions or conditions.

Mayoral development corporations and urban development corporations will also be able to charge for giving pre-application advice on relevant developments within their jurisdictive areas.

The increase comes at a potentially challenging time for both private and public sectors. With increasing planning and development costs, including CIL and S.106, as well as wider uncertainty over Brexit, front-end increases will place an added financial burden on developments, especially on larger schemes. Equally, many planning departments have suffered from cuts to service and are struggling to determine applications within the statutory 8 and 13-week deadlines, as well as dealing with pre-application requests.

The increase in fees is intended that the additional monies will help LPAs to improve planning resources and service delivery, which many applicants will welcome, especially if this helps deliver more certainty over decisions and the time taken to make them.

How the Fee’s have Increased?

The increase covers all current LPA fee’s this is just a highlight of the main fees:

  • Creation of a dwelling house: £462 (currently £385)
  • Creation of non-residential floor space (retail, leisure, commercial, office, etc): 75sqm >     3,750sqm: £462 per 0.75 sqm (currently £385)
  • Maximum OUTLINE: £150,000 (currently £125,000)
  • Maximum residential FULL: £300,000 (currently £250,000)
  • Change of Use: £462 (currently £385)
  • Householder Extensions and alterations: £206 (currently £172)

At LiteBox Architecture we feel communication is key, we aim to keep our clients up to date on important changes given the direct impact they will have. For further clarification of fees check out www.planningportal.co.uk.

For more information on this matter, or how it could affect you, please don’t hesitate to get in touch on 02476 629192 or info@liteboxarchitecture.co.uk

So, you’re thinking that you need more space for the family and you’re in two minds to either extend your existing home or move. This is a common dilemma for most families as space becomes a competition between moody teenagers, kid’s toys, quiet areas and a daily argument over who uses the bathroom first. Well firstly, let’s address the idea of moving house. You have the additional expense to move up the ladder to the next size house along with stamp duty, estate agent’s fees, legal fees and the cost to make your new house into a home so it’s just the way you want it. These costs can quickly spiral out of control but there may be potential to extend or alter your existing home where you may be happy with the location, neighbours and the house is how you always wanted it to be but you just need some extra space. Most clients are either looking for a larger kitchen/dining area or that additional bedroom. The most cost-effective extension to your home is to convert your existing loft space to create either a master bedroom and en-suite or two smaller bedrooms. The space is already there gathering dust and is usually just an ideal hiding spot for the Christmas tree.

The Affordable Way to Add Space to Your Home

The four main essential criteria for a loft conversion are:

  1. Minimum 2.3m headroom that is comfortable, although there is no minimum requirement for building regulations.
  2. Space for a new staircase with minimum 2m headroom, including the landing area at the top.
  3. Traditional roof construction as oppose to trusses (trussed roofs can be converted but are a little more tricky and costly).
  4. Means of escape (protected stair shaft) for fire to conform to the building regulations Part B.

Loft conversions normally take between six to eight weeks to construct from start to finish. There is no requirement for planning approval (unless your building is listed or within a conservation area) providing you stay with the rules of Permitted Development. However, you will be required to submit an application to building control to comply with current building regulations. This can be completed within two to four weeks dependant on current workloads.

I would always advise engaging an architect or architectural designer to create the best design of the space as loft conversions are more specialist and the existing roof structure needs to be properly supported.

Once completed these once dusty, dark inhabited spaces are transformed into large, bright open spaces with a completely different vibe and all the excitement of that magical fantasy room you dreamt of as a child. They provide a space that covers the entire floor plan of your existing house making them spacious and ideal master bedrooms. Further to this, extra space and headroom can be achieved with the addition of a flat roof dormer as part of the design.

With the vast variety of modern material to hand these dormer lofts can be transformed to make an architectural statement and shake off that image of the 1970s/80s ugly box sticking out of the roof. With the addition of cleverly placed glazing and cladding material the space really can look just as magical on the outside as they do on the inside.

What exactly can you expect from our initial free meeting, how can you use the time wisely and what questions should you ask?

Let’s get started and find out more about what to expect and how to prepare for a free home consultation with LiteBox Architecture.


1: What will you achieve from a 30-minute consultation?

Firstly, this gives us a chance to digest two things, your property type and your style of living. From here we can guide you on what we feel is the best outcome, taking into consideration space and your budget.


2: What questions should you ask?

  • What can be achieved for my budget?
  • How will my project affect my neighbours?
  • What materials will be used?

Having some ideas and questions written down to discuss regarding your project is a great idea. Make sure you talk to your partner or family before our visit to understand everyone’s expectations and requirements.

We will listen to your ideas, needs and desires for the planned space you wish to create before we make any suggestions or recommendations.

We will look at the existing style and layout of your home and how this relates to your proposed project. This will also give us the opportunity to assess how your project could affect your neighbours and any other potential issues that could arise.

We will also be looking at how your project can be constructed, thinking of all the construction details and specifications required that meet with your approval and to ensure any building regulations are fulfilled.

Discussing budget is incredibly important and we recognise that it can be a sensitive conversation but it’s always best if you are honest from the beginning with how much you have or can afford to spend on the project. We will always be honest when it comes to telling you if this is in-line with your project’s size and requirements.

We will discuss with you our process of working, from conception to completion, and what would be involved in the work we produce. We will indicate the approximate cost to provide our service, which will be followed up within two days with a written estimate confirming our overall fees to work with you on your project.


3: What questions will we ask you?

To gain a better understanding of how we can add value to your project we will ask you some questions.

  • Do you have the funds in place to carry out the project?
  • Do you have a builder on board or would you like us to recommend someone?
  • Is your home listed, within a conservation area or a green belt?
  • What are you trying to achieve from your project? Additional space, another room etc. We might be able to suggest an alternative approach to gain the same space that could reduce timescales or cost.
  • When would you like to start construction and when do you want it completed by?


4: If you decide to use our services what happens next?

We help to turn your dreams into reality.

The kitchen is always the absolute heart of every home but that doesn’t mean it is located in the right place within your home. The kitchen needs to be located within a part of the home that you enjoy, be that natural daylight, the views or just simply the feeling of the space.

Over the last century, people have constantly adapted their homes to suit the period trends and lifestyle of that era, making current kitchens work in old and period homes. No space has changed more, in design and how we use it than the kitchen. The average family, in the UK, spend around £10,000 to £15,000 modernising and renovating them, at this cost, it is a room that you can’t afford to get wrong.

Open Plan Living

The modern open plan living or kitchen dinner space originated from the humble serving hatch. Over time, this has got bigger from a hatch to the small door opening to walls disappearing completely. Removing the walls entirely brings the two spaces together into one functional room. By removing the humble serving hatch walls entirely kitchens have grown in size and given way to one of the greatest design features of the modern day kitchen, the island unit. The island unit has now become the central hub for any modern kitchen, used as a prepping area, creating a break between the kitchen and other space and a vantage point to enjoy both space and the views through glazed openings.

There are many benefits of open plan living that can be greatly beneficial to your home. It can improve the overall appearance of kitchen, living space, increases the potential for natural daylight and supports communal living in bringing the family together.

Why not get us to take a look and see what ideas we can create, you’ll be amazed at what’s possible. Let’s grab a coffee and discuss your home’s potential today.

If you’re thinking about how to make the best use of the space available to you, watch our video guide to space planning:




Coventry Office

LiteBox Architecture
Unit 7, Colliers Way
Spring Hill Industrial Estate,
Coventry, CV7 8HN

T: 02476 629192
E: info@liteboxarchitecture.co.uk

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LiteBox Architecture
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Hall Green,
Birmingham, B28 8LH

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E: info@liteboxarchitecture.co.uk

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