Sunday, February 21, 2021, 19:16

You are planning to replace windows or doors in your home, but you are wondering if any official formalities are involved. What is allowed and what is not. What do you need to point out? The first question you usually ask is; do I need Planning Permission?

The answer is so, if;

  • the property is listed building
  • the building is in a conservation area
  • If you are a leaseholder, you need first to get permission from your landlord, freeholder, or management company
  • your council has made an Article 4 Direction withdrawing
    permitted development rights
  • you want to replace the standard window with a bay window(is treated as an extension and may need Planning Permission.



 You do not need Planning Permission if;

  • you want only to repair, maintain or improve existing doors/ windows
  • the new doors/windows are of similar appearance and dimensions  to the existing ones


What if I want to insert a new window, e.g., on a sidewall on a higher floor. For example, in a bathroom or a staircase?

Well, such a window must have a reduced level of visibility, i.e., be obscure and non-opening or opened at a height of 1.7 m from the floor level.

ŻRÓDŁO: Permitted development rights for householders Technical Guidance


Obscure glass(prywatność jest definiowana w skali od 1 do 5)

 What if I want to add a new roof window?

New roof windows or skylights usually do not require Planning Permission, provided that;

  • do not protrude more than 150 mm beyond the plane of the roof slope
  • not higher than the highest part of the roof
  • if they are located on the slope of the side facade roof's, they must be obscured and not opened, or opened but only at a height of 1.7 meters from the floor level

ŻRÓDŁO: Permitted development rights for householders Technical Guidance

ŻRÓDŁO: paularthursroofingspecialist



Since 1 April 2002 building regulations have applied to all replacement glazing. The regulations apply to thermal performance and other areas such as safety, air supply, means of escape and ventilation.

Approved Document L


 Thermal heat loss.

"Dwellings are required to be energy efficient. A method of achieving greater energy efficiency is to take steps to reduce the amount of heat that is lost through the glazing in both windows and doors.If you are planning to install windows and doors you should be aware that they need to comply with the requirements of the Building Regulations in relation to the amount of heat that can pass through the glass and framework, which is measured as a U-Value. This U-Value should not be exceeded. For information on the maximum U-Value allowed please refer to Approved Document L-1B, Table 1" (Information from Planning Portal)

U-value = 1.6 W/m2K - for windows
U-value = 1.8 W/m2K - for doors

Approved Document K4

Safety glazing. Safety glazing should be provided to any glass in a critical area. Below is a list giving general view as to when safety glazing is required(Information from Planning Portal).


Approved Document F 

Ventilation. Windows and doors provide ventilation to rooms within a dwelling and rules apply to how much ventilation. The type and extent of ventilation will be dependent on the use and size of the room. For example, rooms where steam will be produced (kitchens, bathrooms, utility rooms etc) should be provided with higher levels of ventilation normally mechanical fans and windows(Information from Planning Portal). 

Approved Document B

 Fire safety

Detailed fire safety regulations can be found in Approved Document Part B. For a house with more floors, an attached garage, or an open plan, these regulations are slightly different.

ŻRÓDŁO: Lacors promoting quality regulation

Finally, I would like to add that for the replacement of windows and doors it, is best to hire a company or a specialist who has the appropriate authorization to issue the so-called FENSA certificate after the assembly works are completed. 

What is the FENSA certificate?

A FENSA certificate is a declaration by the installation company to the homeowner that the windows and doors they have replaced comply with Building Regulations, use energy efficient products, are registered with the Local Council. A FENSA certificate also that verifies that the warranty is insured. Is essential when selling the property.

FENSA doesn’t cover conservatories, porches, new builds, extensions, repairs (frame not included),commercial properties. .

What if a person or company without such authorization performed the assembly work?

Well, in this case, you can make an appointment with an Inspector from your local council or a private company. The Inspector checks on the site the compliance of the work performed with the building regulations. If everything is as it should, you receive a certificate. Probably during the visit of the inspector the job completed,so it is good to have photos showing the stages of work.

ŻRÓDŁO: Internet



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Iwona Joanna Bajorek
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