For full information visit our Extensions page, but basically if the proposed extension has more than 25% of glazing to floor area then you will need to justify this.

 You are in addition allowed to have the area of any existing openings covered by the extension.

For example if the propsed extension is 20.00m² in floor area then you are allowed 5.00m² of glazing.

In addition if the extension covers an existing door with an area of 2.00m², then the total allowable glazing would be 7.00m² for an extension floor area of 20.00m².

There are several ways to offset excess glazing so please visit the Extensions page or Contact Us  regarding Excess Glazing Calculations.