Purlin

A purlin or purlin is a horizontal beam in a roof structure. Depending on where a distinction is made between purlin, Mittelpfette and inferior purlin. Purlins are parallel to ridge and eaves of a roof usually.

The purlin is an intermediate structure in the purlin. She wears the perpendicular arranged above rafters and transfers the load in columns and walls on. The rafter roof comes from contrast, even without purlins. Purlins, which in addition also take on the function of rafters are called Pfettensparren (also Sparrenpfetten ) and can for example be designed as a coupling purlin.

Purlin

The ridge board has its name by its location in the ridge of the roof. It is the highest purlin construction and bear its burdens placed on columns and / or walls from.

Mittelpfette

The Mittelpfette, also Zwischenpfette is between ridge and eaves purlin and is used for intermediate support of the rafter, particularly when larger spans must be bridged. Your exact location depends on design union and static conditions, for example, the possibilities of removing the loads on underlying pillars and walls.

Roof surfaces, or their rafter documents may be supported by several Mittelpfetten. In the wooden roof structures of conventional residential buildings but there is usually only one Mittelpfette per roof surface.

Inferior purlin

The inferior purlin is located at the foot of the rafters. This is typically the area of ​​the eaves of a roof surface. With wooden roof structures of buildings, the inferior purlin is - unlike Mittelpfette and ridge board - often the entire surface of, for example, on a basement ceiling or jamb. In this case, the eaves purlin is considerably smaller dimensions than the other purlin.

Static system in timber

In structures made of lumber come because of the usual wooden lengths ( 6 m ​​to 7 m, a maximum of 9 m) often simply supported beams and two-span for execution. Since the roof lengths are generally about 10 m, two-span beam ( Gerber carrier ) are also coupled to each other or joint carrier executed. An alternative is the use of glulam or steel sections as single-span or continuous beams.

For spans over 4.5 m to 5.5 m and high requirements, for example because of the snow load zone, not enough common lumber dimensions from sometimes. Besides the use of glulam or steel profiles also come with steel profiles reinforced wood cross sections are used.