A Guide to Permitted Development Rights
DOMESTIC PROJECTS – INTRODUCTION
There are many ways to renovate or extend your home without the need for Planning Permission. This is called Permitted Development.
Permitted development rights apply to most properties, however they may be restricted if your home is in one of the following categories:
- It is located in a Conservation Area
- It is located in a National Park
- It is located in an Area of Outstanding Natural Beauty
- It is located in a World Heritage Site
- It is a listed building
If any of the above apply to your project, then you should contact the planning department at your local authority for further information.
Your Local Authority may provide a service which will provide formal confirmation that your project can be carried out under permitted development rights (usually for a fee). If this is not possible you can apply for a lawful development certificate (for a fee) from your local planning authority to prove your development is permitted development. These documents are especially useful in circumstances such as the sale of a property.
In this document we have put together some information to how permitted development rights may apply to common domestic projects. This information is only intended as a guide and we would always
SINGLE STOREY EXTENSIONS
A single storey extension may be acceptable under permitted development rights if:
- No more then half the area of land around the original property would be covered by new additions.
- No extension is forward of the principle elevation or side elevation fronting a highway.
- Materials should be similar to the existing house.
- Side extensions to be single storey and must not have a width greater than half the width of the original house.
- Side extensions to have a maximum height of 4 metres.
- If the extension is within 2 metres of a boundary the maximum eaves height should be less than 3 metres.
- Single storey rear extensions should not extend beyond the rear wall of the existing house by more than 4 metres for a detached house or 3 metres for any other type of dwelling.
- The maximum height of rear extension is to be less than 4 metres.
- The maximum eaves and ridge height of extension is no higher than the existing house.
A loft conversion may be acceptable under permitted development rights if:
- The additional roofspace created does not exceed 40 cubic metres for a terraced house or 50 cubic metres for a detached or semi-detached house.
- Materials are similar to the existing house.
- No part of the extension is higher than the existing roof.
- There are no balconies or verandas.
- Any window in the side elevation are to be obscure glazed and non-opening (unless opening part of window is at least 1.7 metres above floor level).
- Roof extensions are set back at least 20cm from the original eaves, the roof extension can not overhang the outer face of the existing wall.
- Work on a loft or roof may affect bats, a bat survey and a licence may be required before carrying out any works.
- Any extension (such as a dormer window) which projects beyond the roof slope of the principle elevation is not allowed under permitted development rights.
TWO STOREY REAR EXTENSIONS
A two storey extension may be acceptable under permitted development rights if:
- No more than half the area of land around the original property would be covered by new additions.
- The maximum eaves and ridge height of the extension are no higher than the existing house, if the extension is within 2 metres of a boundary the eaves height should be no higher than 3 metres.
- The extension does not extend more than 3 metres beyond the rear wall of the existing house or is within 7 metres of a boundary opposite the rear wall of the house.
- The roof pitch of the extension should match the existing house.
- The external materials are similar in appearance to the existing house.
- Any window in the side elevation of the rear extension should be obscure glazed and non-opening.
- There are no balconies or verandas
A porch may be acceptable under permitted development rights if:
- The area of porch (measured externally) does not exceed 3 square metres.
- The highest part of porch does not not exceed 3 metres.
- No part of the porch is within 2 metres of any boundary which fronts the highway.
Development of outbuildings may be acceptable under permitted development rights if:
- It is not forward of the principal elevation of the existing house
- No more then half the area of land around the original property would be covered by new additions.
- It must not be separate, self contained living accommodation.
- It must be single storey with a maximum eaves height of 2.5 metres and an overall height of 4 metres (with a dual pitched roof) or 3 metres in any other case.
- If the outbuilding is within 2 metres of a boundary the building should not exceed 2.5 metres in height.
- No balconies or verandas are allowed under permitted development rights. Raised platforms such as decking are permitted development provided they are no higher than 300mm
So you’ve decided you want a new extension, but where to start? The big question we often get asked at an early stage is “Do I need an Architect?” The short answer is… it depends.
If the project is very small and very straightforward, it is entirely possible that your building work can be undertaken by a builder without the need for drawings or the involvement of an Architect. Most of the time, however, the form and extent of the building works are not pre-determined, and some design work is required, if for nothing else than to accurately define what the builder is pricing for. Depending on the size and complexity of the project, this drawing work can include everything from initial sketches, through Planning drawings, to Technical drawings to satisfy Building Regulations and for the builder to price and build from. For everything other than the most basic extensions, this is more than simple ‘drawing work’ and involves some design, whether it is basic space planning, conceptual design sketches, or detailed technical design.
So, assuming the project isn’t very small, it is definitely best to have some design drawings, but does an Architect need to do them? Unlike in some countries in the world, there is no requirement by law for an Architect to be involved in a project, and there is also no protection of the function of an Architect. That means that anyone is allowed to perform the job of an Architect. They are not, however, allowed to call themselves an Architect. Under the Architects Act, only people who have undertaken the relevant training and paid their dues to the Architects Registration Board are allowed to call themselves an Architect. As such, you will find a lot of ‘architectural designers’ on the market, who are not Architects.
So what’s the big deal?
Why not hire an ‘architectural designer’ to do your drawing work for a fraction of the price? There are several reasons, but in short, you have no protection or reassurance that they are competent.
To be a registered architect, you have to undertake approximately 7 years of training, usually involving two separate University degrees, and two stints of on-the-job training. Much of this focuses on the ‘Design’ side of things, but the final professional examinations cover many crucial aspects of the work like contract administration, health and safety, project management, dispute resolution etc.
Architects are also bound by the ARB’s Code of Conduct. This deals with all kinds of aspects including Honesty, Integrity and Competence. Any architect who falls short of the requirements can be reported to the ARB who will hold disciplinary procedures and they have the power to reprimand, issue a hefty fine or remove the architect from the register.
Another key requirement of the Code of Conduct, is the requirement to maintain appropriate Professional Indemnity Insurance. This is important because it protects both the Architect and the Client. If the Architect is negligent and disaster strikes, you may seek legal action and be awarded compensation. The compensation awarded is entirely likely to be more than the Architect can pay, meaning the Architect is bankrupted, and the injured party does not receive all that is due to them. If the Architect is insured, the insurance company pays this compensation.
There is no legal requirement for ‘architectural designers’ to maintain Professional Indemnity Insurance, or have any design, technical or professional training whatsoever. There is also nobody to complain to if the service falls short of the level expected. This means the Client may be unprotected if something goes wrong. There’s nothing to say that some ‘architectural designers’ might have PII or be competent at their job, but the Client needs to be very careful.
In addition to the Architects Registration Board, there is the Royal Institute of British Architects, or RIBA, which you are likely to have heard of. Unlike the ARB, there is no requirement to be a member of this, it is purely a members organisation. They do, however, have their own, even stricter standards and codes of conduct. RIBA Chartered Architects and Practices are required to comply to a wide range of policies from Health & Safety, Quality Management & Equality.
Where to find an Architect
If you want to hire an Architect and you are not sure whether an individual is a registered Architect, you can visit www.arb.org.uk and search the register. You will find all four of the partners at Carve Architecture. Similarly, you can search the RIBA’s website for Chartered Practices at https://www.architecture.com/find-an-architect/practices/search where you will also find Carve Architecture.
Cost of Domestic Extensions
NOTE: This article was originally written in 2020, including projects completed prior to this. See note at bottom of page.
One subject that comes up on every project is, of course, cost. We all only have a certain amount of money, and want a clear idea of how far our budget can go. It is always a hard one to tackle, as every project is different, and every client has differing needs and levels of specification. We are not cost consultants, and the best way to get an accurate price is to speak with a number of builders. That said, what we can do is look at past projects and see what price they came to.
For this piece, we have chosen to look at a number of examples from the past few years of extensions we have completed in and around York. Each of these have an element of extension and some refurbishment of the existing house. To make for a fair comparison, we have discounted some of the more variable aspects of work, namely:
- Kitchen supply and fitting
- Bathroom supply and fitting
- Floor finishes
- External works
We have then made an assumption that the costs of the refurbishing elements of the house are at a rate of rds that of the extension. We have assumed that loft conversions, needing new floor construction, dormer windows, insulation etc are at the same rate as extensions. It is a fairly crude tool, but the best approach without going into full detail, and useful as a guide.
Case Study 1
- Single storey rear extension, replacing an existing Kitchen offshoot, which was completely removed
- Some internal re-working, including the creation of an internal shower room.
- The glass doors to the rear were a reasonably high spec, and the roof was covered in a sedum green roof.
- Extension Floor Area= 27.66m2
- Internal Refurbished Floor Area= 18.93m2
- Total Project Cost= £80,900+VAT
- Project Cost minus variable aspects= £65,655+VAT
- Area based price (extension)= £1,630+VAT/m2
- Area based price (refurbished)= £1,087+VAT/m2
Case Study 2
- Single storey rear extension, connecting to existing extension
- Significant internal re-working, with multiple levels
- The sliding glass doors to the rear were a very high spec, as was the window. The overhanging roof would also have added to the costs. There were serious access restrictions.
- Extension Floor Area= 10.56m2
- Internal Refurbished Floor Area= 32.63m2
- Total Project Cost= £141,907+VAT
- Project Cost minus variable aspects= £78,410+VAT
- Area based price (extension)= £2,427+VAT/m2
- Area based price (refurbished)= £1,618+VAT/m2
Case Study 3
- Single storey rear extension, with 2 storey section containing first floor bathroom. Loft conversion with dormer window
- Whole house refurbishment
- Generally a fairly standard spec throughout
- Extension Floor Area= 29.85m2
- Internal Refurbished Floor Area= 58.62m2
- Total Project Cost= £140,162+VAT
- Project Cost minus variable aspects= £130,337+VAT
- Area based price (extension)= £1,891+VAT/m2
- Area based price (refurbished)= £1,261+VAT/m2
Case Study 4
- Single storey rear extension, loft conversion with dormer window. Stand alone Garden Office
- Whole House Refurbishment
- Generally a fairly standard spec throughout. The Client undertook the cladding of the garden office themselves to help control costs.
- Extension Floor Area= 51.94m2
- Internal Refurbished Floor Area= 72.74m2
- Total Project Cost= £115,725+VAT
- Project Cost minus variable aspects= £93,429+VAT
- Area based price (extension)= £930+VAT/m2
- Area based price (refurbished)= £620+VAT/m2
Case Study 5
- Single storey rear extension, replacing existing galley Kitchen. Loft conversion with dormer window
- Some internal re-working to top floor plus first floor windows
- Generally a fairly standard spec throughout. Wildflower green roof on extension
- Extension Floor Area= 26.45m2
- Internal Refurbished Floor Area= 20.00m2
- Total Project Cost= £82,966+VAT
- Project Cost minus variable aspects= £68,818+VAT
- Area based price (extension)= £1,730+VAT/m2
- Area based price (refurbished)= £1,153+VAT/m2
Case Study 6
- Single storey rear extension, replacing existing conservatory, with two storey section housing bedroom.
- Whole house refurbishment, including rendering of house and replacement of all windows. Price includes for installation of ground source heat pumps and piping
- Generally a fairly standard spec throughout
- Extension Floor Area= 36.85m2
- Internal Refurbished Floor Area= 107.07m2
- Total Project Cost= £185,830+VAT
- Project Cost minus variable aspects= £158,824+VAT
- Area based price (extension)= £1,467+VAT/m2
- Area based price (refurbished)= £978+VAT/m2
As can be seen from the figures, there is some variation, which reflects a number of things, including complexity of project and also economies of scale. Looking at the full house refurbishments, they generally are able to achieve a better overall rate compared to smaller extensions which have more foundations, insulation, structure per floor area than the larger projects. Generally, we are finding the rates for extensions are in the region of £1,400-£1,900/m2 with refurbished areas at £950-£1,300/m2. There are some outliers where an extremely cheap or expensive rate is achieved, but these are the exceptions. There may be several reasons why these don’t fit in the normal pricing banding. The expensive one was a high spec job, in particular with the glazing. There were a lot of external works included within the overall contract sum, and while I have discounted these, it is entirely likely the contractor made allowance for these works within the other prices and then post-rationalised the external works price out. Again, I would like to stress that there is no real science in the above, and floor area based estimations are a pretty blunt tool. When considering an area based estimation, don’t forget to add in the VAT, or to allow for all of the aspects we have discounted.
NOTE: This article was originally written in 2020 with projects completed prior to then. Since then, there have been significant financial pressures on construction so for domestic extensions we are generally advising that a square metre rate of upwards of £2500+VAT/m2 should be used as a starting point. [October 2022]