This simple angular style from Bartholomew is based upon a traditional design, and features roof vents for ventilation. This all-glazed structure, (H)400x(W)300x(D)300cm, in Lizard Green, costs around £30,000 (including installation)

Conservatories have come a long way since their origins as a Victorian plant house. Although they are often separated from the main property by a door, today’s interpretation often sees classic and contemporary designs offering much-needed room for overspill from the kitchen, dining space or living room.

What is a conservatory?

Simply put, a conservatory is a glazed addition to a home that can be built without planning permission (see more below as restrictions apply), and differs from an orangery which tends to have a partially solid roof and a higher proportion of solid wall. There is not a hard and fast definition of a conservatory, but they are not usually considered part of the habitable home, or as some put it, they are not part of the insulated envelope of the home as they are separated by an exterior-grade door.

Local Authority Building Control (LABC) guidance states that conservatories are exempt from Part L of the Building Regulations (the part relating to thermal performance), as long as:

  • at least 50 per cent of the walls are constructed from translucent material
  • at least 75 per cent of the roof is made from translucent material
  • the floor area does not exceed 30m²
  • the conservatory is at ground level
  • heating must be independent of the main dwelling (or operationally independent through zoning)
  • glazing meets Part N (safety in relation to impact opening and cleaning) in critical zones

It is however, these high levels of glazing that can lead conservatories to get a bad press due to the concern of overheating in summer and being freezing cold in winter.

Do I need planning permission for a conservatory?

For many, a conservatory’s appeal lies in the fact that it is often considered permitted development (exempt from needing planning approval), but bear in mind that there are restrictions and you will definitely need planning permission if you are in a Conservation Area or making changes to a listed building.

Applying for a Certificate of Lawful Development from your local authority will prove helpful when reselling a property.

How much does a conservatory cost?

Most people will hire a conservatory design and build company for ease, but if you are of a practical nature, you can do it on a DIY basis to save money.

  • DIY conservatories can cost as little as £3,000 and come in a range of standard designs, ready for installation by your chosen builder.
  • Bespoke conservatory companies offer individual tailor-made design and installation services. Mid-range styles typically cost £10,000-£15,000.
  • High-end designs can easily exceed £35,000- £50,000, which includes advice on planning, design and build issues.

As a rule, buy the best you can as, unless the build is well planned and executed, it could detract rather than add value to your home. The Royal Institution of Chartered Surveyors says a good conservatory can add at least five per cent in value.

Getting the design right

The design of a conservatory should echo the design of the existing property, so don’t mix architectural periods, such as by adding a Victorian-style conservatory to a Georgian house. Using materials and scale sensitively should give a convincing finish, but this does not always mean following traditional lines – take inspiration from your home’s architecture.

Consider the Conservatory’s size in relation to your house, too. An oversized design would look out of place with a modest house, and a larger property will need a more substantial structure.

Having the space for a conservatory is an important factor, as you could lose a large part of your garden to build it, but its shape can be flexible. Although often thought of as rectangular, a T-shape, L-shape or octagonal room can serve your purposes well. If you want to use it as a dining space for six to eight people, a room size of at least four by three metres is recommended.

What you intend to use your conservatory for will generally dictate where it is positioned, but, if this isn’t obvious, use the new room to create a feature on a plain aspect of the house.

Ventillation and temperature control

A south-facing building will need ventilation from opening side windows and roof vents (these can be automatic), creating a through draught to shift hot air. Low-emissivity (low-e) and tinted glass will also help the problem of excess heat, but some varieties of tinted glass may also dull the daylight in winter.

Be sure that you understand how much it will cost to ‘run’ your conservatory in terms of heating and cooling. As a general rule, glazed roofs provide better thermal performance than a polycarbonate roof. And, if the conservatory faces north, it may need radiators or underfloor heating to keep it at room temperature year-round.

Underfloor heating and trench heating are efficient and space-saving, while a woodburning stove takes up room but makes it feel instantly cosy. Whatever heating system you choose, you need to be able to operate it independently of the adjoining rooms.

Glazing technologies

With overheating a major concern for many installing or updating a conservatory, look at the solar control glazing available. You can also get polarising glazing that tints to reduce glare. Automated blinds can be installed as another line of defence against solar gain.

Aid ventilation and cooling with thermostatically controlled rooflights that open automatically. Choose ones with rain sensors so that they close themselves too.

Self-cleaning glass is another popular choice on modern conservatories and essential if you want a low maintenance addition.

How to choose the right company to build your conservatory

It’s important to find the right firm to help you with your project. If you are going to require planning permission or will be building something subject to Building Regulations, it is recommended that you choose a company who can cover third-party approvals. Party wall approval might also be a concern, so ask whether they can help you with this too.

Reputable companies will also offer guarantees for elements of their work such as the structure or glazing.

On top of this, seek references from friends and do your research. Just as you would with any building project, check out prior examples of their work.