Many people who see it will probably not even recognize it as such - the cross roof. Because optically it is strongly reminiscent of the most famous roof shape with the gable roof. In fact, the cross roof is visually and structurally closely related to the gable roof. We explain its peculiarities, advantages and also weaknesses in the following clearly and easily comprehensible.
The cross roof - what's behind it?
The creation of the cross roof is as simple as the obvious shape suggests. Should, instead of a building with one main direction, a building with two mutually perpendicular Main directions, i.e. a cross shape, are roofed over, one takes the well-known gable roof and duplicates it just these 90 degrees. The result is a roof with two equivalent ridge directions and two usually at least approximately equivalent roofs, as well as a total of four equivalent ridges - the cross roof. However, this equivalence must not be confused with the fact that these roofs are identical. Because they can vary in their width, height and, as a result, the height of the eaves. Even variants with different roof pitches are known. The characteristic feature of the cross roof, however, is the same ridge height of the two jumbled gable roofs.
Similarities to other roof shapes
In terms of optics, the cross roof can be strongly reminiscent of other sub-shapes or Additions to the gable roof remind:
- Transverse or mid-gable
- Gable dormers
- Roof loggias with a gable roof
Depending on the perspective, these do not even have to be arranged on both sides, but rather it
Such an element is sufficient to give the impression of a crossed roof depending on the location.The delimitation
Although the transitions between a double gable on a gable roof and a real cruciform roof are certainly not made of stone are chiseled, this can be clearly recognized by the identical height of both roofs in connection with the continuity of both roofs. Although an extremely pronounced gable can raise the ridge at the level of the main ridge, it usually lacks the opposite counterpart that would make it a real cross roof.
The construction
Theoretically, it is possible to have a cross roof analogous to the classic gable roof, as well as a rafter roof to form mutually supporting rafters, or as a purlin roof with load-bearing thresholds, central purlins and ridge erect. However, this statement only applies to the actual roof quarters with opposing roof areas. In the intersection area, on the other hand, the roof surfaces with their structural elements meet at right angles, so that there is no mutual support. This means that when erecting a rafter roof, the roof intersection must always be reinforced with additional frames or supports. The purlin roof, which works with additional load-bearing elements from the start, has a clearer structure.
Constructive details
Particular attention is paid to the structural details of the cross roof. Because by the equals
- Throat: Intersection line to be formed between the individual roof surfaces in both the supporting structure and the roof covering
- Section lines roof surfaces: with regard to the structure, roofing, snow guard etc. to solve
- Ridge: four ridges that meet at one point
- Purlins: statically intercepting points of intersection of the individual purlins of the roof surfaces
- Drainage: eight individual gutters, each with a slope, which meet in pairs
Static challenges
The greatest structural challenge of the cross roof is the fact that in the pure form of this roof no load-bearing element is continuous from ridge to ridge. There is always a change of direction in the intersection area of the roofs, which must be designed statically and, if necessary, supported in a load-bearing manner. In practice, this often means that the cross roof in the crossing under the converging At the top, a supporting frame structure takes the loads from the purlin ends and the ridge intersection catches. You can tell that she eats through the four characteristic supports under the intersections of the central purlins.
NOTE: A very common solution to counter these static difficulties is to offset the two ridges against each other by the height of a ridge beam. As a result, a ridge can be built continuously and serve to absorb the loads of the two roof parts that are perpendicular to it. Strictly speaking, this implementation is no longer a real cruciform roof, but the difference in design is only marginal due to the offset of approx. perceived half to full brick height. The benefit for the interior, on the other hand, is enormous due to the fact that the support structure in the intersection area is largely eliminated.
costs
Anyone who is thinking about using a crossed roof for their planned building will sooner or later also be asked about the construction costs. Even if a binding specification of the costs apart from a specific object is hardly possible, it is possible to Identify individual tendencies well and cite aspects that, for example, compared to the classic, simple
Gable roof mean an increase in costs, or also contribute to reducing costs.Cost-increasing aspects:
- High constructive effort
- Large number of details to be solved
- High proportion of envelope surface in relation to volume and base area
On the other hand, the following have a cost-reducing effect:
- Simplifying alternative using offset ridges
- Good use of angular buildings and difficult to build plots possible (additional costs for the roof are absorbed by larger / better usable building area)
- High degree of repetition of structural details due to four-fold repetition of the comparable roof or Roof part
In conclusion, it can be said quite clearly that the cross roof itself is certainly a very expensive one Roof shape represents. It is economically advantageous above all if it enables a building shape through which a plot of land extends can be used better and more intensively, so that my more roof costs with more usable or living space goes hand in hand.
Advantages and disadvantages
Even if the tendency of the merits and also the difficulties of the cruciform roof have been mentioned again and again, they should be named here again in a nutshell and summarized.
advantages
- Allows dense development of difficult properties
- With constructive simplification through height-offset ridges, the roof space can be used well
- Balanced look thanks to equal roof parts and gable
disadvantage
- Constructively complex
- Only possible for floor plans with a right-angled arrangement
- Comparatively high costs, which can usually be offset by advantages in building design
- High susceptibility to damage to the high degree of detail points, such as valleys, ridges, verges and eaves
TIP: Before you decide to plan a cross roof, it is always worthwhile to consider alternatives such as the gable roof with transverse gable or dormer windows. Because the central center of the four roof parts also means effects in the building below due to the necessary transfer of loads.
