Regulations that need to be followed when installing double glazing include building regulations and planning permission guidelines. These ensure the windows are installed correctly and meet certain standards. These regulations vary depending on the property, so it’s important to check with your local authority before installation. For instance, if you live in a listed building or conservation area, permission is normally required before making any changes.  Under Planning Portal rules, you do not need to apply for planning permission for new double glazing units, as long as they have a similar appearance to the original installation. Therefore, if you plan to replace a double-glazed sash window with a bay window, this will be classed as an extension and may require permission. In general, you’ll need to ensure the windows are installed correctly and that they are the correct size for the opening. New windows installed in an upper floor side elevation must have obscure glazing. They must also be either 1.7 metres above the floor or non-opening. In addition, you’ll need to ensure that there is enough ventilation in the room to prevent condensation. The best way to do this is by hiring a qualified glazier with an excellent understanding of the current regulations. Ensure the installer you choose is registered with the Fenestration Self-Assessment Scheme (FENSA), as this means the company is pre-vetted to carry out installations that comply with building regulations. Working with a FENSA installer also means you won’t have to register the installation yourself, saving you time and effort.