When a roof window is enough (and far cheaper)

The question is often framed as a matter of taste, but there is a hard dividing line underneath: do you want light, or do you want space? A roof window delivers light. A dormer delivers headroom and usable floor area.

The price gap follows that line. Fitting a roof window costs € 800-2,500; a plastic dormer € 6,500-11,000 and a bespoke timber one € 10,000-20,000. That is not a small surcharge for a bit more comfort — it is a different category of work.

The practical test is simple: go and stand in the spot in question. If you can stand upright there and there is floor area you are not using because it is too dark, a roof window solves your problem. If the roof slopes so steeply that you are stooping, a roof window changes nothing about that — you get light, but the space stays unusable.

Two things that shift the choice. One: a dormer more often needs a permit, certainly on the street side — count that lead time in. Two: two roof windows side by side give more light than people expect and still cost less together than the cheapest dormer. Every guide rate is in the price index.