The purlin roof

The purlin roof is the roofing version most frequently found in German-speaking countries, although it is not the classic roof truss in our latitudes. Like the rafter roof chair, the purlin roof has its own advantages and disadvantages, which we would like to inform you about below.

Hintergründiges to the purlin roof

The result is the Pfettendachstuhl from a flat roof construction. The first was a pent roof, later the saddle roof and other, similar attic versions. This roof structure was widespread, especially in the Mediterranean region. Bit the Romans this construction came then to Central and Northern Europe.

The purlin roof trims replace the rafter roof

Until then, north of the Alps, the rafter roof chair was the typical roof truss. Depending on individual needs, it also offers advantages over the purlin roof, but the outstanding benefit of the purlin roof is more flexible construction options and larger spans possible. In addition, you can also combine the purlin and the rafter roof.

The purlin roof: purlin

Construction of the purlin roof

At first glance, the structure of the purlin roof is very similar to that of the raftered roof chair, but it still has significant differences. Thus, both roof trusses have rafters, but the weight of the Pfettendachstuhl is derived over purlins and supporting pillars. When rafter roof chair, the weight of the compelling rafters of both roof halves on the rafters is derived.

Elements of the purlin roof

Therefore, the rafter roof chair complicated Drempel constructions are necessary (knee stick), which accounts for the purlin roof. The structure of the purlin roof is as follows.

  • Foot purlins (in the area of ​​the eaves point)
  • one or more middle purlins
  • a ridge purlin
  • Support

Construction forms of the Pfettendachstuhl

The supports of the purlin roof can be single-row vertical, then it is a simply standing chair. With two rows of support posts standing, it is a double standing chair. However, if the purlins are straightened at an angle, it is a lying purlin roof chair. Moreover, the rafters erected on the purlins do not necessarily have to face each other (both halves of the roof).

Advantages and disadvantages of the purlin roof

This results in a whole range of advantages that make the purlin roof too popular.

  • hipped roof constructions are also easy to construct (including crippled hipped roof)
  • large and heavy dormers can be set almost arbitrarily
  • the fireplace can be set almost arbitrarily
  • Span widths of up to 14 m are possible with a purlin roof
  • for flat designs low wood requirement
  • no complicated drumming construction

The disadvantages

On the other hand, there are some disadvantages. For example, the support beams for the purlins can interfere with planning loft conversions. Depending on the design, you can also integrate the support beams in partitions.

Supporting walls and wood requirements

In addition, the support beams should not derive the load exclusively on the floor of the floor below. Rather, pay attention to load-bearing walls, which must be integrated accordingly. With steep purlin roofs, the wood consumption is higher and is additionally reinforced, as a steep purlin roof must also be protected against wind.

Purlin roofs: a conclusion

Whether you decide on a purlin or a raftered roof chair, depends very much on which roof shape is preferred by you and how you want to use the attic. Advantages and disadvantages of the purlin roof have to be compared with those of the rafter roof to determine which roof structures offer you the most advantages.

Tips & Tricks

The purlins are also called Rofen in a purlin roof. These are connected via a Aufklauung (Pfettenanker example) with the rafters.

Of course, we also offer articles in the house journal about the other roof shapes, including the rafter roof.

Video Board: What Is A Roof Purlin? – House Framing And Construction