When Does A Conservatory Become An Extension?

Written by  Harry Taylor
Last updated: July 28, 2023

A growing number of people are spending money to extend their homes in order to make them larger and more valuable. Whether you opt for a conservatory or an extension, you’ll need to consider how much space you’d like to add to your home.

It’s a common misconception that house extensions and conservatories are one and the same. Nonetheless, they differ significantly, making them the best option for homeowners interested in a glass addition in terms of conservatory extension.

Conservatories and extensions are often interchangeable, but they are not the same. This article will investigate the transition point between a conservatory and an extension. Or when the conservatory extension happens.

What Makes a Conservatory an Extension?

When a conservatory goes beyond what is allowed under PDR (permitted development rights), it is considered a conservatory extension and needs to be approved by the local planning authority. So, what exactly are the rights to build a conservatory?

The term “permitted development” refers to areas where construction can occur without obtaining special authorisation from the local government. It is not necessary to obtain building permits to install a conservatory if the following conditions are met:

  • Your conservatory is limited to the side of your home.
  • The highest point of your conservatory won’t exceed 4 metres.
  • Compared to the area around the main home, your conservatory doesn’t even take up half of it.
  • The peak of your conservatory roof will not exceed the peak of your main home’s roof.
  • The eave height is less than 3 metres in areas where the conservatory is less than 2 metres from the border (the edge of the enclosed zone surrounding the house).
  • When adding a conservatory to the front or side of your home, ensure it is not any closer to the sidewalk or street than the house itself.
  • You don’t encroach on your neighbour’s space by installing anything that can make them uncomfortable.
  • If your home is detached and you want to build a rear conservatory, the addition cannot be more than 4 metres from the house’s original wall. This distance shouldn’t exceed 3 metres if your home is attached to others.

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What’s The Difference Between a Conservatory & an Extension?

Despite their seeming similarities, the two expansions are actually rather dissimilar. 

First of all, a conservatory is a glass-enclosed room added to a home, and it may be built in a wide variety of ways using various kinds of glass. Dwarf walls are the typical structural underpinnings for this. Building rules must be in place before a conservatory can be constructed, which can be time-consuming.

A house extension is likewise made out of glass walls and a roof, and dwarf walls may also support it. But it is typically constructed within pillars that offer more support and stability. As a result, the extension becomes much stiffer than the conservatory. Hence, wind damage is nothing to worry about.  

An extension to your home offers superior thermal efficiency and may help you cut costs on your monthly energy bills more than any other choice. In addition to making your home seem better from the interior and outside, a well-designed home extension can significantly increase your property’s value.

It can be difficult to decide between a conservatory and an extension. But when you know what they mean, you can pick the best one for your house. 


With their glass ceilings and walls, conservatories have long served as outdoor living spaces. Plants and other green life were nurtured with the ensuing natural light. These glass conservatory extensions are a popular choice for homes today because they provide a great return on investment and don’t require major renovations. 

They are typically glass extensions on the back of houses. While glass is standard, a tiled roof can be installed without special permits.

Below are some interesting facts about conservatories:

Low Efficiency In Terms Of Energy Use

Since most conservatories don’t employ insulated walls or high-performance glass, they waste a lot of energy. Insulation is a common problem with conservatory roofs.

Uninhabitable Living Spaces

They are not considered “livable” since conservatories do not have a traditional home addition’s structural integrity or thermal efficiency.


Even while conservatories can be constructed without a formal building permit as long as they fit within the parameters of permitted development rights, they still need to be approved by an LABC (Local Authority Building Control) surveyor to comply with the Building Regulations.

More Affordable Than Extensions 

Conservatories are typically less expensive than expansions due to the shorter construction time, cheaper materials, and less square footage needed.

House Extensions

House extensions, in contrast to conservatories, serve various purposes. A new addition is a worthy financial commitment because of the extra room it provides and the aesthetic value it adds with its glass walls and modern layout.

Here are some common facts about extensions:

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As a major change to your home, an extension requires approval from both the local planning office and the Building Control department.

Customized to a Higher Degree

Homeowners commonly enlist architects to design the extensions because such plans are necessary as part of the planning application procedure.

Greater Adaptability

They can be built anywhere and serve various functions. They can upgrade to a year-round kitchen, bedroom, bathroom, living room, or dining room.

High Durability

For added strength and stability, robust house additions have pillars that are unlike those used in conservatories.

Not Very Cheap

The costs of an extension are typically far higher than the costs of conservatories.

Low Energy Consumption

Regarding heating and cooling costs, double glazing can be a lifesaver because of its superior insulation.

conservatory Victorian roof

How Do You Convert a Conservatory into a House Extension?

Knowing the differences is crucial to turning your conservatory into an extension. Conservatories are more open and use 75% or double glazing. However, an expansion is more like your current home.

Converting Conservatory Walls

It’s crucial to inspect the conservatory walls for conservatory extension. Solid walls can be built around your conservatory and replaced with new windows with extensions. This will warm, secure, and protect your space. 

A strong wall keeps heat in, lowering energy expenditures. Heat retention will improve the extension’s usability. Solid walls also block rainfall, making them soundproof. This blocks outside noise, making it suitable for loud neighbourhoods.

New Doors for an Extension

New conservatory extension doors connect your new extension and yard, improving your home. This gives more natural light and a greater connection to your home. An extension supports inline slider bifold doors. This simplifies garden access for you and your family.

Replacing Glass with Solid Roofs

Conservatories needs a sturdy roof to become extensions. Homeowners prefer solid roofs for their insulation and durability. You can also install a roof lantern or customise the conservatory ceiling. 

Tiled roofs are lightweight and weatherproof, making them excellent for traditional designs. The holes keep rainfall out.

What Are The Advantages & Disadvantages of Turning a Conservatory into an Extension?


  • Size is solely limited by funding and possibly planning.
  • Permitted Development may apply.
  • It can be two-story and almost any shape or style.
  • It can be designed and clad to match your property.
  • They’re durable and may outlast a conservatory.
  • Increases home value
  • Insulated to maintain a comfortable temperature year-round.
  • lets you alter your layout
  • It can be installed on your home’s front, side, or back 


  • They cost more than conservatories
  • Disrupts your living arrangements more.
  • They may need planning approval.
  • Building Regulations permission is needed.
  • It takes more time to build than a conservatory.
  • Costs might escalate quickly.

How Much Does it Cost to Convert a Conservatory into an Extension?

The price of a typical conservatory extension can be rather high. Costs might begin at roughly £4,000 for a replacement roof on a Victorian-era conservatory. A solid or tile roof would likely cost an additional amount. The cost can increase if you want solid walls and even more if you want sliding doors.

You won’t spend as much as you would have if you had built a new conservatory, though. It will be easier, but you can acquire a much nicer place for the same price or even less.

Converting your conservatory might be expensive, but many options exist for reducing this expense. One great option is to use a regional business rather than a nationally recognised one that charges a premium for conservatory extension.

Should I Choose a Conservatory or a House Extension?

The final decision will be based on one’s own preferences and available resources. Extending your home, however, seems like a better use of resources in terms of time, money, and square footage.

To begin, unlike extensions, conservatories do not retain heat as well. Thus, they are significantly chillier in the winter. Although a heater will help, nothing beats the comfort of your own home’s thermal insulation and warmth.

On the other hand, a wider range of potential undertakings can be considered while working with an extension. However, a conservatory’s size, breadth, and materials will restrict your choices.

Though extensions are more expensive than conservatories, we believe it is better to put that money on something that will be useful in the long run.

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