Rules for Extending a House without Planning Permission

You’ll be pleased to hear that you can build an extension to your house without needing planning permission. This is possible thanks to permitted development. To be eligible for permitted development (PD), the extension must comply with certain rules and criteria. Before you begin your project, it is important to understand the rules and criteria. You can avoid being in trouble with the law by understanding these rules and criteria.

We’ll go through the following topics in this article:

• Extending on to a property without obtaining planning permission
• Advantages of extending without permission.
• Basic criteria for extending Without permissions
• Indemnity insurance
• The larger home extension plan

As well as other more helpful hints! You can acquire a Udex quotation here if you’re about to add that extension.

The advantages of extending without obtaining planning permission

• Permitted development is not a matter of opinion. You already have an excellent notion of what is acceptable so that you can build inside that framework.
• If your planning risks are decreased, you’ll be less likely to incur hidden fees, such as reapplying for permission.
• Permitted development rights are an excellent alternative for anyone living in an area with a high rate of planning refusals because they operate outside of the council’s own (sometimes strict) standards.
• Permitted development rights may help hone in your concept and provide your designs with a starting point now that the guidelines are in place.

Basic requirements for extending a home without obtaining planning permission

If you want to extend your house without getting permission, you must meet three conditions.

Since 1948, have you or any previous owners extended the house?

If a house has been extended before, either by you or prior owners, you will need planning permission to do so. This provision applies to extensions made after the 1st of July 1948.

Is your property listed, or does it sit on “designated land” (conservation land)?

Permitted development rights are limited or cancelled for listed homes and homes on designated lands (conservation areas, areas of outstanding natural beauty). If your home falls into this category, we strongly advise that you seek professional advice when designing an extension.

What is your property type, a house or flat?

Permitted development only applies to houses. Other property types, such as flats and maisonettes, will necessitate a full planning application. Also, if your home has previously been converted, you may not be eligible for approved development rights.

You can book a free architectural advice call and consult with a UDEX expert to ensure that your project is compliant.

Plan for a larger house extension

The larger house extension plan, which was abolished in 2020, enabled homeowners to erect single-story back extensions that were larger than permitted development rights allowed. Its allowances were added to approved development rights once it was disbanded. This meant that homeowners could still build larger extensions, but the process would be slightly different today than it was when the larger house extension program was in place.

Homeowners who want to build larger extensions may now request for approval in advance. You can extend a detached home up to 8 meters for detached houses and 6 meters for other types of residences with prior approval.

Permitted Development Rules

All changes that you are allowed to make without permission must be outlined in the 1995 town and country planning (General Permitted Development Orders).

Some examples are as follows:

For most extensions:

• The extension cannot take more than half the land around the original building.
• A building extension can’t be higher than its tallest portion, nor can it exceed the height of existing eaves.
• A building too close to the highway can’t have either a side or forward extension.
• Once the extension is within 2m of the boundary, the extension’s height cannot exceed 3m.
• The extension is not allowed to include verandas or a microwave antenna, or a chimney. It also cannot alter the roof of an existing house.
• The exterior materials of the house must match the exterior materials of the extension.

Rules for attached vs detached properties

• Extending an attached property beyond the original house’s rear wall by more than three meters is prohibited.
• Detached homes cannot be extended beyond the original home’s rear wall by more than 4 meters.

Single-storey extension

• It should not extend beyond the rear wall by at least 4m in detached houses and 3m in other types of houses.
• It should not exceed 4m in height.

Two-storey extensions 

• There must be a match in roof pitch between this expansion and the original home.
• Side elevation windows on the first floor should be non-opening and obscured glazed. This rule applies only if the window is not more than 1.7m away from the floor.

Front extensions

Permitted development allows you to build a house extension in front of your home, provided that your front extension is permitted:

• Is a single-storey building.
• Don’t put your front end in the middle of the road.
• It shouldn’t be more than 3m from the original house.
• It shouldn’t be more than half the original house’s width.

Extensions for porches

Without planning permission, you can build an extension to your porch, presuming that:

• The porch’s maximum height is 3 meters.
• It is at most 2m from any border next to a highway
• The external ground area should not exceed 3m2.

Rear house extensions

• For detached houses, single-storey rear extensions can extend up to 4m and for other houses up to 3m. With prior approval, this can be increased to 8m or 6m.
• Rear extensions of a double-storey can be extended up to 3m from the original home, provided it is not further than 7m from the rear wall.

Side house extensions

• Only one story is possible.
• The maximum height allowed is 4 meters.

Basement conversions

The basement can be converted without authorization as long as you have the right permits. Such as:

• It is not an independent unit
• It’s not necessary to excavate a basement in order to build a new one.
• The usage has not been significantly altered
• A lightwell will not change the exterior appearance of your home.

To replace a window

If the windows being replaced are identical to those that were previously installed, you don’t require planning permission.

To tear down internal walls

Planning permission isn’t required if your house isn’t in a conservation area or isn’t listed.

Rooflights

To permit roof light installation to be covered by permitted development:

• The rooflight should not extend beyond 15cm above the roof’s slope
• It cannot extend forward from an elevation facing a highway.
• The property cannot be found in exceptional natural beauty or conservation areas.
• If it is placed on a side elevation, it must not open or rise more than 1.7m above the floor.

Loft conversions

• Cubic content must not exceed 40m3.
• The height of the dormer windows cannot exceed the height of the existing roof.
• Dormer windows cannot be extended forward from the roof plane of the principal elevation.

Garage conversions

Garage conversions are permitted as long as they are internal and do not involve enlargement. A detached garage is the only exception to this rule. If your garage is constructed after your house, you should check with your local authority to make sure that your home hasn’t been restricted from development.

Conservatory extensions

The same development guidelines apply to conservatory extensions as house extensions. They cannot be more than the main house, and they must not take up more than half the land.

For shed/garden room extensions

Generally, sheds and garden rooms are considered extensions under planning development rights. To erect a shed or other outbuilding without a permit:

• The outbuilding can’t be placed in front of the main elevation.
• It should be one-storey, with a maximum height of 2.5m.
• They cannot be used in residential accommodation such as bedrooms or annexes.

To build a new fence or wall

Authorized development rights allow you to build and maintain a new fence or wall if the following conditions are met:

• When it is adjacent to a highway, its height does not exceed 1m.
• It is not higher than 2m for any other wall or fence.
• The property is not listed.

Swimming pool

Permitted development allows you to build a swimming pool in your garden, provided it does not take up more than half the garden’s curtilage.

For solar panels

A solar panel can be added to a roof under permissive development, provided that it does not extend beyond 200mm from the roof or wall and that the panel’s highest point does not exceed the roof’s highest part.

Book a free architectural consultation to discuss your project and get a Udex expert.

Is it possible that my house won’t be as “sellable” if I don’t get planning permission?

Your home’s value may be affected if you don’t have proper planning permission. How? As long as the new owner has the necessary documentation, they might be held liable for any violations of the law that occurred while they were building their new house.

Retrospective planning permission

While it is more common to get planning approval before a project can begin, there are cases when the project had already started before approval was sought.

Retrospective planning permission is needed in such cases. Retroactive planning permission permits you to apply for approval after the project has been started.

Be careful! If your application is denied, you will have to return the items as they were.

It is always more advisable to get planning permission before you start any project.

Indemnity insurance

This is usually when the seller can’t provide planning permission for any extensions or additions to their home at the time of sale. This is when the conveyance solicitor will advise the buyer to obtain indemnity insurance. Indemnity insurance covers the buyer against any legal problems that could arise regarding the building’s compliance. It is important to note that indemnity insurance does not cover any repairs, replacements or installations.

To summarise, you can save money and time by extending a house without planning permission. The extension must meet specific criteria and rules to be considered eligible for permitted development, and these rules govern almost all aspects of your house extension proposal.

Udex is a one-stop solution for homeowners who want to renovate or extend their homes. Our experts can handle everything, from financing to planning permissions.

Now you know the basics of what to do. It would be smart to begin your project. Get a quote today.

You can still use our calculator to estimate the construction cost of your project.

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