- For spans between load-bearing walls up to 6 meters
- With main puff
- With rafter tightening
- For a span between load-bearing walls from 6 to 9 meters
- Combined tightening
- Vertical supports
- For spans between load-bearing walls from 9 to 14 meters
In this article we will tell you what a gable roof rafter system is. We will consider the main elements of which it consists, as well as their location in the rafter structure, how to properly install wooden rafters and what are the main elements of the rafter system called.
In the previous article, we talked about the advantages and disadvantages of different types of roofs. A gable roof is the simplest and most reliable construction for a residential building. In addition, it implies the presence of an attic, which is so useful in a suburban economy..
The gable rafter system has several basic varieties, on the basis of which the craftsmen create individual designs. We’ll look at them in order of complexity..
For spans between load-bearing walls up to 6 meters
This option is the simplest, while it carries the smallest load. It uses hanging rafters with a main or rafter tightening. With this design, the rafter system is only rafters connected at the intersection in the ridge.
Rafter beam or tightening– an element of the rafter system that connects the rafter legs of opposite slopes with a horizontal traction.
Rafter leg or rafters– the main bearing element of the roof supporting structure. A roof slope is formed from a row of rafters.
Hanging rafters– a method of installing rafters in which there are no additional horizontal fasteners (rods).
Mauerlat(wood trim for the top of the walls) is the basis of the rafter system. Installed on stone walls without fail.
By the location of the puffs, such a roof is of two types.
With main puff
The tightening runs along the tops of the walls and rests on them. It is in this case that the ceiling beam most often plays the role of tightening. The height from the ceiling to the ridge is from 1.4 to 2.5 m.This option is optimal if you plan to use the attic space for temporary storage or drying of something.
- Additional utility room in the attic.
- Attic space is fully used.
- Significant air supply – less heat loss through the roof.
Disadvantage: relatively small room volume.
With rafter tightening
Is the tightening at the level? height from the support of the rafters to the ridge. In this case, there is no connection to the floor, and the supporting walls of the rafters can be raised to the required height. Does it allow you to create full-fledged rooms with wall heights? floors.
- Saving on the wall material of the second floor.
- The most efficient use of the rafter space.
- Possibility of a residential attic space.
- High-quality roof insulation is required.
- Inset of roof windows required.
For a span between load-bearing walls from 6 to 9 meters
With an increase in the span, the number of supporting and tightening elements increases. This is necessary to effectively distribute the load and transfer it to the walls. Hanging rafters on a span of more than 4 meters * can be arranged in only one way – double (combined) tightening. In this case, the span length * should not exceed 4.5 m.
* – in this case, the span means the length of the projection (shadow) of one rafter leg in the design position.
When a double puff is installed, the rafter is called a crossbar.
1 – tightening; 2 – crossbar; 3 – rafter leg; 4 – mauerlat
Often you have to splice the rafters in length, because 6 meters is not enough. In this case, additional intermediate supports are arranged. They can be located in different areas relative to the rafter leg. In this case, the rafters are no longer called hanging, but layered.
Rafters– rafter legs with one or more supports. An exception is the attic gable rafter system with two rows of supports, located off-center.
Headstock or center support– a vertical post located at the intersection of the rafters.
Run– a solid board or bar connecting a row of rafters or beams.
Ridge run– connects the top of the central struts (headstock).
1 – tightening; 2 – grandmother; 3 – run; 4 – ridge run
In addition to the central row of racks, the structure of the rafter system can provide for additional vertical supports – in the middle of the span of one rafter leg. Compared with strut-braced reinforcement methods, this method is convenient in that it does not block the passages. If the attic is high enough, you can use it as a storage room.
Mansard rafter system– a special case of a gable roof with vertical supports. It does not have a central row of racks, only racks on? projection of the rafter leg. It always has a crossbar (rafter tightening). A row of crossbars forms the ceiling of the attic floor.
For spans between load-bearing walls from 9 to 14 meters
With such large spans, the length of the projection of the rafters will be from 4.5 to 7 meters, and in most cases the splicing of the rafters along the length cannot be avoided. This, in turn, will require reinforcement at the junction of the rafters and the use of struts.
Brace– an emphasis located in the design position at an angle.
The braces can be installed in different places of the rafters, but not closer? their length towards the end. There are many options for installing them. The easiest way is to install on a bed..
Sill– a solid board or timber installed on the supporting beams perpendicular to them. Serves to distribute the load from the struts and struts on the beams.
1 – beam; 2 – brace; 3 – bed; 4 – grandmother
Basically, the strut support is located at the place of the headstock support, especially if they are located on an intermediate bearing wall. Otherwise, there may be no central support – only struts, but they must be fixed to the rafter leg closer to the middle of the span.
A special case of a combined gable rafter system is an attic floor with a span of more than 4.5 meters. In this case, a U-shaped frame is arranged – girders from a 100×100 bar, a row of vertical racks along the beds on? or ? rafter projection length and horizontal tightening (crossbar). The remaining space is filled (unfastened) with struts. This type of rafter system is used on buildings of a large area..
Gable trusses with struts have two significant advantages:
- high load-carrying capacity and spatial rigidity;
- the ability to create strong, gentle slopes of great length.
At the same time, the slope of the slopes is due to the low height of the ridge above the floor, i.e., the attic is not used in most cases.
When choosing a gable roof, remember that in addition to the relative simplicity of the device and installation, it is necessary to properly organize the distribution of the load. This is especially important in areas with significant snow and wind loads. Spring snow is 2.5-3 times heavier than winter snow, so additional supports and struts in the rafter system will not be superfluous.