Is a Conservatory an Extension?


A conservatory is defined as having a transparent or translucent roof. It is a relatively painless structural addition in that as most of the work takes place outside the house, conservatories are mostly exempt from Building Regulations (see below), and the duration of the job is relatively short. Building a conservatory is much cheaper than a brick-and-block or timber frame extension and when complete it often turns out to be an extremely versatile room which, if properly designed, can increase the value and appeal of a property. If the proper materials are used, and sufficient attention is paid to the heating and ventilation, then a conservatory can soon become one of the most lived-in rooms in the house.

Building Regulations

In England, Wales and Northern Ireland but not Scotland, the structures of smaller conservatories are exempt from Building Regulations control provided their floor area does not exceed 30 sq m (325 sq ft). Other rules may apply:

• safety glass must be used in doors and low-level glazing in the conservatory to comply with Part N of the Regulations

• structural alterations creating new access routes into the conservatory from the house must comply with parts A and L

• there must be ventilation openings (such as patio doors or French windows) in the conservatory, and in any habitable room that will be ventilated through it, to comply with Part F of the Regulations. The doors must have an opening area equal to five per cent of the combined floor area of the two rooms. In addition, each room must have background ventilation, with a minimum open area of 8,000sq mm (12 sq in)

Planning permission

Some people may tell you that a conservatory does not require planning permission because it is classed as a ‘temporary structure’, but if you listen to them then you should also listen out for the sound of breaking glass as the council’s JCB demolishes your illegal conservatory. A conservatory counts as an extension to a building, so planning permission will be necessary if:

• your proposed extension or conservatory increases the volume of the house by more than your permitted development rights

• your permitted development rights were surrendered in order to obtain the original planning permission for the building

• the extension or conservatory is closer than 2 m to the boundary with your neighbours and more than 4 m high

• it is higher than any part of the original structure

• it projects from the front of the house towards the highway, or towards a footpath at the back (this may mean one that is long-forgotten), unless there would be at least 20 m between it and the highway or footpath

• it will take up more than half of the garden

• your deeds forbid it. Sometimes deeds have restrictive covenants inserted to preclude any further development, particularly in multi-occupancy dwellings where the freehold is shared or operated by a limited company. Take legal advice as to whether it is possible to have these covenants put aside.

The most common problems

• Water penetration

See below.

• Ventilation

A certain degree of ventilation is specified in the Building Regulations, hut if you want to be sure you don’t wilt in the summer months (bearing in mind that the UK climate is getting hotter), you might want to consider fans, blinds and roof panels that open — as well as openable windows.

• Heating

In the winter even double glazing saps heat fast, so some kind of heating is necessary to prevent the conservatory from becoming a no-go area due to the cold. Under-floor heating is one option; extending the existing central heating (with one or more radiators or heaters in the conservatory) is another.

• Cleaning and maintenance

How are you going to clean the conservatory, particularly the roof? Arc the sides strong enough to support a ladder leaning up against them? Will the roof take your weight if it is spread across a board or plank? Is this a safe option? Most conservatory owners end up investing in a mop with a very long handle. Your installer will be able to advise you on cleaning methods.

• Access to other windows

How are you going to clean or paint any first-floor or second-storey windows above the conservatory? One solution to this is to replace any windows above the conservatory with maintenance-free windows (painted aluminium or PVC-U, for example). Reversible hinges allow both sides of the window to be cleaned from the inside. Otherwise, scaffolding over the conservatory may be needed. Note that conservatories should not be placed so that ladders cannot be put up to high windows (in a loft conversion, for example) that are intended as means of escape in the event of fire.

• Security

How good are the locks? Will the structure compromise security? Ideally, secure locks should be fitted to a conservatory from the start. It is possible to add extra locks if the original ones are inadequate. This may be a good time to install motion detector-activated security lighting. This could make you unpopular with your neighbours, however, as every passing cat, fox and badger may activate it.

• Manholes

If your conservatory covers one of these, you will have to get digging to make another one — and limber up your wrist for some serious form filling as manholes (inspection chambers) are covered by the Building Regulations. Alternatively you could have a double-seal cover on the existing manhole.

• Downpipes and soil pipes within the site

Generally conservatories arc located on areas of the building which are free from downpipes arid soil pipes, but if there is no other option these pipes can be moved. This can be a time-consuming, ugly (and smelly) business which may require permission, and should not be embarked upon lightly.

The biggest problem: water penetration

One of the most common reasons for a surveyor to be called upon to provide expert testimony is water penetration in conservatories. Because conservatories are lightweight constructions without structural regulations, general builders often assume that a strip of lead (flashing) set half an inch into the mortar will be sufficient to seal the join. However, water can penetrate the external wall higher up, above the flashing, and run down on the inside of the cavity wall. This moisture will then re-emerge through what used to be the external wall, but is now the finely skim-plastered and wallpapered back wall of your new conservatory. Bubbles in the plaster (and flickering wall lights) mean that moisture has penetrated. The only answer is chiselling out a row of bricks above the flashing and installing a cavity tray, which must catch the rain and channel it away from the conservatory. Ideally this should be done before the conservatory roof glazing goes in, rather than afterwards.

The sequence of events

1. The site is cleared and excavated This means levelling off the ground, repositioning downpipes, etc.

2. Foundations are laid and a ‘dwarf’ wall, to carry the walls of the conservatory, built incorporating a damp-proof course (DPC). The existing outside wall (soon to become the inside wall) should already have a DPC installed.

3. The base is put down There are no Building Regulations to be met, but the specific instructions from the conservatory manufacturer should be followed carefully. A concrete base 75-150mm below the DPC is advisable. Channels should be left in the base for ducts leading to airbricks (if the conservatory base would otherwise cover these up) and for electric wiring and central heating pipes if required.

4. The structure is erected This is usually modular steel, aluminium, PVC or timber. Weatherproofing the join is usually done using lead flashing, which should he tucked a full inch into the mortar.

5. The cavity tray is installed, if you are having one (see above).

6. Roof and side panels are glazed.

7. The electrical supply is connected, wall lights are fitted and wired up, the ceiling fan connected and the electrical supply connected to the mains. The heating radiators are connected up.

8. Plastering (if required), finishes (painting, varnishing woodwork and floor treatments) and flooring Plastering will conceal any electrical cables or plumbing work, though many people leave the existing wall finish as bare brick, render, stucco or pebbledash.

Timescale: Approximately six weeks. The case for using a specialist You may buy a conservatory, and then find a contractor — perhaps the conservatory manufacturer can recommend one. Or you may rely on a specialist firm to provide and build the structure.

If you use a general builder to fit a conservatory, it will probably end up being more expensive than employing a specialist. For a start, he might have to pay more for the materials: a specialist will deal with a conservatory supplier maybe 20 or 30 times a year, and is likely to get a better deal than a contractor making a one-off purchase. Also, the general builder will be at a disadvantage regarding the speed of his deliveries, and will probably accomplish the job more slowly. Full-time fitters know what they are doing when it comes to glazing and will routinely use superior grades of glass, with better thermal and energy-saving properties.

Finding a conservatory specialist

The Conservatory Association* is a trade body with a national database of 300 members who can supply and install conservatories. They have a code of practice and occasionally expel members for deviating from it, though most of their calls are for advice from consumers who have employed non-members.


26. June 2011 by admin
Categories: Extensions and Conversions | Tags: , | Comments Off on Is a Conservatory an Extension?


Get every new post delivered to your Inbox

Join other followers: