Planning permission for a loft extension is not normally required as they usually fall under Permitted Developments (PD) as you are not changing the existing footprint of the house, however, your design will need to adhere to a number of specified parameters. Permission could be required where you extend or alter the roof space exceeding specified (see below) limits and conditions.
Your architect or builder will normally check and confirm whether you will need to get planning permission, but as a guide, if your proposed conversion satisfies the conditions below you should not need to obtain planning permission.
Do I need planning permission?
- The total area of the additional space created does not exceed 40 cubic metres for terraced houses or 50 cubic metres for detached or semi-detached houses. This includes that of any additional extensions that may have been made to the roof of the house.
- The extension does not reach beyond the outermost part of the existing roof slope at the front of the house
- No part of the extension is higher than the highest part of the existing roof
- Materials are to be similar in appearance to the existing house
- There are no verandas, balconies or raised platforms
- Side-facing windows are obscure-glazed ie. frosted or patterned
- Side-facing windows or openings are 1.7m or more above the floor
- Your house is not on designated land, like national parks, Areas of Outstanding National Beauty, the Broads, World Heritage sites or other conservation areas
- Roof extensions, other than hip-to-gable ones, are set back as far as practicable, at least 20cm from the house’s original eave.
- The roof extension does not overhang the outer face of the wall of the original house.
Note: If your home in semi-detached or terraced, then you will still need to notify your neighbours of your planned work if it falls under the regulations of the Party Wall Act.
So while you may not need planning permission, loft conversions always need approval under Building Regulations (irrespective of whether they need planning permission)
This is completed by a building control surveyor who inspects the conversion at various stages and will be responsible for issuing a completion certificate upon final inspection.
Lawful Development Certificate
Even if your loft extension does not require planning permission if you wish to sell your property in the future you will be asked for a Lawful Development Certificate (LDC) to prove that your loft conversion was built lawfully. A Lawful Development Certificate (LDC) is not mandatory but highly recommended, which is why we always obtain this for our clients.
Loft Conversion Building Regulations
If you plan on extending beyond the limits and conditions of Permitted Development, or your property is listed or located in a conversation area, then you will need to apply for planning permission.
Before you start your loft conversion project you have take into consideration any building regulations related to conversions, as all home development projects in the UK need to comply with certain standards for design, construction and alterations. These are the regulations that will be relevant to your loft conversion:
- Part A – Structural safety: Making sure that the loft wall, floors and joists are sturdy and there is sufficient headroom in the loft.
- Part B – Fire safety: Ensuring there is a suitable escape route in the event of a fire and that the right smoke detectors are installed.
- Part E – Resistance to sound: Ensuring there is an adequate sound proofing in your loft conversion.
- Part F – Ventilation: Ensuring there are enough air vents and windows to adequately ventilate the converted space.
- Part G – Sanitation, hot water safety and water efficiency: Ensuring that all plumbing has been installed correctly and safely.
- Part L – Conservation of fuel and power: Ensuring that the converted space is property insulated to conserve energy.
- Part P – Electrical safety: Ensuring that all electrics in your loft have been installed by a qualified electrician.
The full Building Regulations 2010 can be found here for further information.