The main types of roofs that are used are:
From one water, with only one slope, so that the water runs in only one direction.
Of two waters with two skirts and a ridge, the water runs in two directions.
Half a pavilion with a square or rectangular floor plan, with three skirts or slopes.
In a square or rectangular pavilion, four skirts and a vertex.
Of one or two waters with skirts
Single or double water with skirt and mojinete
A la mansarda, with broken skirts
Saw teeth or shed, with two slopes, which provides perfect illumination
In the roofs of various slopes the pairs of lima-tesa and lima-hoya should be highlighted. The tesa file pairs are placed in the salient angle formed by the intersection of two slopes, those of lime-hoya, in the incoming angle.
Inclination of roofs:
The different inclinations of the roofs depend on the materials used for roofing, on the different climatic factors and on the purpose for which the covered room is intended.
Roofs with a slight slope: Roofs with a slope of no more than 5° are designated as such.
Medium slope roofs: this category includes roofs with slopes of between 5o and 40o.
Roofs with steep slopes: more than 40o inclination.
Roofs with straps:
In the case of houses with a narrow width in order to be able to fix the rafters, some eaves straps are placed on the longitudinal walls and then, as a top support for the rafters, another ridge strap, which goes from one of the transversal walls to the opposite one. In this way the rafters are supported in the manner of beams inclined on the belts so they will be requested to simple flexion. As far as transverse rigidity is concerned, the walls that support the belts are used. The rafters do not absorb front loads. The positions of the rafters on both sides of the roof are independent of each other.
For larger distances between transverse walls (gables), which support the belts, secondary supports must be placed, which can be resolved by means of props, or they can be transferred to a solution with reinforcement or a plywood solution.
The recommended distances from the economic point of view for the supports of the belts oscillates between 3,5m and 4,5m being also the recommended distance for the light between the supports of the rafters, since when this distance is increased the necessary squadron increases and therefore the cost (we remember that in the dimensioning to flexion the determining element is the moment that in turn grows with the square of the distance).
The separation between rafters is usually taken between 40 and 60cm, although sometimes it can reach values of 70 to 80cm but it should be borne in mind that the greater separation will involve an increase in the section.
On the other hand, as the section of the rafters increases, the section of the straps will also increase and the cost will increase.
In short: the solution adopted will take into account structural considerations without losing sight of the economic aspect for the construction to be adequate.
In general the lateral belts as they are supported on the load-bearing walls the predominant effect on them is the overturning for which a wider section than high will be used, whereas in the case of the ridge, for being submitted to flexion and on it to act important loads will be higher than wide and of greater section than the rafters. In these cases, multi-laminated beams are usually used which have a higher admissible tension than the common solid sections.
When the span of the rafters exceeds 4.5 m, intermediate belts can be used, which may or may not replace the ridge. In the first case the belts can be supported on intermediate posts and these in turn rest on transverse beams that will transmit the loads to the load-bearing walls (in order to reduce the necessary section of the belt). In all cases it must be taken into account that the loads must be carried to the bases in some way and try to analyze the solution that implies the lowest cost by studying not only the lowest consumption of material but also observing the necessary labor.
High slope roofs:
High slope roofs, due to the action of the wind, require greater transverse rigidity than low slope belt roofs. A triangle must then be formed.