Secondary glazing manufactured and fitted to a timber bay window. This format of secondary glazing is common in Europe. Essentially, a second window is fitted into the reveal. The secondary windows open inwards so the original bay window remains intact with its windows opening outwards. This type of secondary glazing is less conspicuous than aluminium sliding secondary glazing and it works well in keeping out draughts as well as traffic noise, which is particularly useful if you live on a main road.