Dirty trick No. 6:- Non matching windows.

It is a requirement for some elements of PD building works that the materials are to be of similar appearance. This also applies to the windows. Therefore if your proposal seeks to have a style and size of window or door that does not reflect the existing house fenestration then many Planners have declined the C of LD on this basis. The only time that a clear cut design difference for windows and doors can be allowed for PD is when the extension is a conservatory.

Therefore if your design of property has small windows and modest French doors sets then an extension with a 6M wide bi-fold door set and large picture windows could be considered as not complaining with the materials of similar appearance requirement.

Suggestion:- Consider changing all your existing house windows to the new style for the extension. Many extension schemes trigger existing house upgrades in any case so if this is your own aspiration then also show this on the application plans. Alternatively alter the plans to make the windows and doors fit in with the design and appearance of the existing property and do what you like during the build. This is taking a chance and is not without risk for the homeowner but most councils would not consider it ‘expedient’ to pursue a homeowner on this very dubious technical point.