Probably the most common type of residential extension is the two storey side extension. However, it is one of the most easiest schemes to get wrong with regard to Planning Permission. Side extensions have an awful lot of issues that need careful consideration before submitting a scheme to the Planning Department for Planning Permission.
Firstly is the impact of your scheme upon the neighbours. Most councils design guides will not let you build right up to the boundary at the first floor level. This is to prevent ‘terracing’ of the street scene. This usually means ‘insetting’ the extension by at least 1M. The ground floor element can normally go closer.
Secondly, is respecting the shape of the existing dwelling. This often means setting back the extension to obtain broken wall & roof lines together with a lower ridge line. Simply adding on a ‘block’ of same depth extension with flush front elevation wall & roof lines will normally be resisted.
This is to prevent large bland wall & roof areas. Having broken wall lines retains the original house shape, adds interest & is subordinate to the main dwelling. The most common reply to this design concept from home owners is ‘but it will look like an extension!’ Yes if it is done badly but no if the design accommodates good design detailing, respectful scale & well designed roof slopes. It really does not take much effort to achieve the right balanced look – just the right eye & lots of design experience in such matters.
Thirdly are side windows of adjoining properties. These need to be carefully assessed for right of light issues. Some side windows are not relevant – others are – you need to decide which ones are which.
Fourth is the off road car parking requirements. Additional bedrooms often means additional or compliant off road car parking provision. If your property is already deficient in this area & known to be within an on road parking problem area with perhaps access problems onto a busy classified road then you may have to consider what you will be formally presenting to the Planners in terms of potential new bedroom spaces.
Lastly is the overall width of property scenario. All properties have a dimensional ratio (width versus depth). Many properties are already long & thin with a wide street scene or presence. A two storey side extension will often just add to this visual impact which is again often resisted by the Planners. Clever design tweaks such as recessing the extension further back from the front elevation & wrapping it around the rear elevation can often create the additional space required but without making the property look ungainly wide.
The same result can be achieved by bringing the extension further forward & wrapping it around part of the front elevation. Many people seem to think front extensions are impossible because of infringing ‘building lines’ but the fact is front extensions are becoming far more popular & acceptable due to the improvement of the street scene. Many front extensions can turn a really bland looking property into a very interesting building with interesting roof & wall lines. Property developers do this all the time but that can fill another topic on its own.