Dormer Windows versus Roof Windows

by / Thursday, 07 June 2018 / Published in Articles

In countryside locations full two storey houses can look out of place and planners may insist on a one and a half storey or dormer bungalow (as they are sometimes known) design.

Dormer windows offer some aesthetic appeal but have little else to recommend them. The additional floor area provided is minimal and they are an expensive addition.

More importantly, at a time when building regulations demand high levels of insulation and airtightness, dormer windows are a potential weak point in the roof design. And, the relative complexity of dormer windows means they are a maintenance issue in the making.

Designing houses with dormer windows can be a bit restrictive particularly if they are located on opposite sides of the roof. In such circumstances it is important they align so, as to avoid unnecessary complications in the roof design.

Dormer windows require triple ply girder trusses each side, to form the opening and distribute loads, which add significantly to the roof cost. So long as opposing dormer windows align you can fit two of them between each pair of trusses.

There are several roof window sizes which fit in standard truss spacings, thereby eliminating any additional roof construction cost. These can be positioned virtually anywhere and coupled horizontally and vertically to provide larger areas of glazing, if required. However, if a larger, single area of glazing is required then girder trusses will still be required.

Modern roof windows can be supplied triple glazed and come with an insulation collar for around the window which reduces heat loss and eliminates cold bridging. A U-value as low as 0.81 W/m2K can be achieved – much better than most wall and roof constructions.

Norscot believes roof windows provide a much cleaner appearance, in tune with modern house design and much better value for money. In line with our ‘Keep It Simple, Make It Better’ ethos we no longer build dormer windows into standard designs but are happy to offer them for custom designs, if required.