A helmet (also "tower helmet", "helmet roof" or "roof helmet") is a pointed roof shape in architecture for towers with a square, but mostly polygonal floor plan . This roof shape is often found on church towers .
Tower helmets with a pyramid-shaped basic shape are distinguished from tower domes with a curved, bell-shaped structure. Mixed forms are common.
Due to their height, spiers have a special aesthetic significance for the silhouette of cities. The architectural design of the spire can vary widely. Often there is an imperial stem at the top as a bearer of the church tower crown.
The helmet roof traditionally sits on a massive stone tower shaft . In contrast to the tower shaft, the helmet roof usually has a light wooden roof truss in a carpenter's construction or a supporting structure made of steel . The roofing was often done with lead or copper sheet, roof slate , shingles or roof tiles .
Occasionally, spiers were made of natural stone (e.g. the south tower of Chartres Cathedral , around 1160, height 105 m), later also pierced with Gothic tracery (e.g. the tower of the Freiburg Minster , around 1330, height 116 m or the extraordinary tower of the Brussels City Hall , around 1455, height 95 m).
Tower helmets are exposed to strong wind pressure, which can even lead to twisting - examples of this are the tower helmets of St. Clemens in Mayen or St. Pankratius in Kaisersesch .
In the past, lightning strikes due to the exposed location often led to fires in the wooden structure inside, which could hardly be extinguished due to the poor accessibility. Today almost all helmets are protected by lightning rods . Fires occasionally arise during roofing work.
In some cases the helmet takes up approximately two thirds of the total height of the tower. Examples of this are the tower of St. Michaelis Church in Hamburg and the tower of Petrikirche in Riga .
The onion helmet with a hood-like shape was created in the Baroque era . This type of roof was mainly built in southern Germany and Austria . First you can find them by the towers of the Frauenkirche in Munich .
Rhenish helmet in St. Castor, Koblenz
Classic Gothic octagon tower helmets crown the Marienkirche in Lübeck
Copper-covered Gothic spiers (left) and Welsche hoods ( onion domes ) (right), Naumburg Cathedral
Welsche hoods on the Jesuit Church in Vienna
Other roof shapes
Photo documentation of the new building of a tower helmet in Dortmund
- ↑ Binding, Koepf: Picture Dictionary of Architecture .