Understanding Replacement Windows in Conservation Areas and Listed Buildings

What is a conservation area? 

Restrictions to properties in conservation areas when replacing windows/doors

Living in or working on a property in a conservation area might mean that the house is affected by special controls – which are called 'Article 4 Directions'. These restrict work you can normally do without planning permission such as replacing external doors or windows.

These controls are tailored to each area by the council and are put in place when there are particular elements of local buildings they want to protect.

The homeowner should be aware of the restrictions or allowances placed within the Article 4 directive and in many cases will have to have had planning permission granted. It is imperative that the installer checks these measures prior to agreeing a contract to undertake replacement window/door works.

Where an Article 4 directive is not in place, planning permission must be granted prior to any work taking place.

Are there building regulation exemptions in conservation areas?

No, there are no exemptions to building regulations in conservation areas.

However, under the advice of the planning authority, it may be determined that particular features of a modern window are not desired due to a detriment in characteristic design (the features that make it unique) – in this case, for example, the planning authority may decide that trickle vents should not be incorporated into the window(s).

It is important to say that this is not an exemption. Background ventilation must still be provided to the property but in an alternative form to trickle vents, such as through wall or mechanical ventilation.

Can I register installations in conservation areas with FENSA?

Yes, you should register these with FENSA. You may be asked for proof of the planning decision should any specific instructions be in place, eg no trickle vents.

How do listed buildings differ?

It is important to note that listed buildings cannot be registered with FENSA. These must be notified directly with the local authority building control. Controls and protections are stricter with listed buildings and planning permission is required.

Are there building regulation exemptions in listed buildings?

Similar to conservation areas, exemptions are extremely rare.

The most common exemption is overall thermal efficiency. Due to design restrictions, in exceptional circumstances it can be found that a replacement window/door cannot meet the regulatory requirement set out in Approved Document L, in which case a central pane* u-value of 1.2 W/m²∙K would be permissible due to the need to protect the characteristic of the building.

(*central pane = the thermal performance of the glass units alone)

In addition, the planning authority have the ability to exempt an installation from compliance requirements of certain approved documents. The planning authority is the only department that can grant this permission.

In summary: 

1 - Replacement windows/doors in conservation areas should be registered with FENSA, listed buildings should not.

2 - In most cases, planning permission is required when replacing windows/doors in conservation areas.

3 - There are no automatic exemptions to building regulations, only the planning authority can approve window/door designs that exclude features that are required to meet building regulation compliance.