Loft Conversion Dormer Designs - what are the options

Over half of all loft conversions will incorporate a dormer window design many of which will be built under the sites permitted development (PD) allowances. This is where you can build certain structures to a dwelling house without the need for formal Planning Consent.

However, the rules relating to PD rights for dormer windows designs are very complicated and a professional assessment needs to be made by your house extension designer or architect right at the start as this will affect the final design of a loft conversions dormer window.

If formal Planning permission is required for your dormer window design, then big box dormers are normally resisted by the Planning Department as they can look incongruous and unsympathetic for normal roof slopes - totally out of scale. I am sure most homeowners have seen an example of these monstrous big box dormers on some houses - if not simply take a train ride between any town in the UK and you will observe all manner of hideous extensions and dormer designs facing onto the railway tracks.

If you discover that your dormer window does require formal planning permission then the external design will need to fit into the Planning Departments planning policy for dormer windows. Most will refuse big box dormer window designs. What they want are smaller dormer windows usually only of the size to fit the window required. That normally means a 1200mm wide (4ft) 2 module window and preferably under a matching pitched roof.

This could mean having more than one dormer window within the roof slope and provided the finished design appears balanced and in scale this can be very acceptable even for three dormer windows for some larger existing roof slopes. Most Planning Policy will not endorse a dormer windows use for solely adding extra walking head height. Therefore should your dormer design have a large amount of walling either side of the window then this again will usually be resisted.