The rafters

The rafters are important design elements in both purlin and rafter roofs. However, there are, depending on the particular roof form, significant differences in the load on the rafters. Below, we will not only show you the respective advantages and disadvantages, you will also receive further information on rafters.

Origin of the name rafters

The term "rafter" finds its origin in Middle High German in the Middle Ages. It can already be seen how significant rafters have always been north of the Alps for roof structures. The word equates to splayed or upright beams - just as rafters are installed.

Here you can find rafters

You can find rafters on different roof structures. The two most important roof types in German-speaking countries are the following ones.

  • Pfettendachstuhl
  • Rafter roof

Tasks of the rafters

Both trusses can also be combined with each other. The importance of rafters is rather subordinate to the purlin roof. In the rafter roof chair, on the other hand, it is the rafters that divert the entire weight. The weight that the rafters have to derive is made up of several factors.

  • Net weight of the rafters
  • Roofing (eg concrete or tiled roof tiles)
  • Snow, rain, wind

Rafter at the purlin roof

In the case of the Pfettendachstuhl, the rafters direct the weight directly onto the purlins, which in turn guide it over the supports to the building ceiling. From there it is derived via the facade and load-bearing walls. Thus, with the purlin roof no particularly difficult substructure is necessary.

Rafters in the rafter roof

But this looks different with the rafter roof chair. All weight is derived here via the rafter foot. But these forces also act outwards. In order to be able to absorb this enormous pulling force without problems, this roof truss has to integrate a difficult drumming construction between the building upper deck and the rafter roof truss.

Rafter: here is insulated

On the rafters themselves, the transverse battens are now attached. The is mounted for later roofing with the roof skin. Depending on whether the technical roof design is a hot or cold roof, the insulation is still in between. The insulation of the roof truss is also differentiated according to the position.

  • Rafter insulation (outside)
  • Intermediate insulation (from the outside, but often from the inside)
  • Upper or lower rafter insulation (from the inside)

Rafters and EnEV

For the next few years it is particularly important for existing buildings to have intermediate and sub-rafter insulation from the inside. Because according to the EnEV (Energy Saving Ordinance), many homeowners are gradually forced to dam their attic accordingly. This is the case, for example, if you buy an existing building without existing insulation according to EnEV.

Insulate the roof truss efficiently

The intermediate and Aufsparrendämmung from the inside is then often the only inexpensive way to comply with this insulation. In the intermediate spar insulation, clamping felt mats are clamped between the rafters. In the Aufsparrendämmung they are attached to it. Of course, combinations are possible.

Maintenance of the roof truss including the rafters

With all these aspects, the rafters of a roof truss repeatedly come into the focus of a homeowner. In addition, as a homeowner you should not forget that the rafters as the entire roof requires regular maintenance. This is the only way to detect wetness damage or pest infestation in good time and prevent large follow-up costs.

Tips & Tricks

In the house journal, we offer you numerous articles, guides and instructions on various topics around the roof. For example, to the purlin roof.

Video Board: The Jokerr - The Rafters