Fastening of rafters to mauerlatu

The reliability of roof construction directly depends on how correctly the entire of its carrier system will be mounted. And the main its elements are rafters. The whole system consists of rafter legs that support and propel additional elements, such as struts, pins, bolts, side rails, pillars and stretches. Rafting legs are connected to the ridge beam from above, and their lower edges are often supported by the Mauerlat, fixed on the side bearing walls of the building.

As the largest load falls on the Mauerlat, it is made from a powerful beam. Its cross-section is determined by the massiveness of the entire rafter system, but in general the size is from 150 × 150 to 200 × 200 mm. This load-bearing element nt pr is designed for uniform distribution of load from the entire structure of the roof and roof to the bearing walls of the structure. Fastening of rafters to the Mauerlat is carried out in various ways. They are selected according to the type of rafter system(

which can be stratified or hanging), its complexity and massiveness, from the magnitude of the total loads, which will be subjected to the whole roof construction.

Varieties of connection points « rafters - mauerlat»

First of all, there are sliding and rigid fastenings of rafters to the Mauerlat.

1. Sliding fasteners consist of two separate elements, one of which is able to move relative to the other.

These mountings can be different in design - closed and removable .

• The closed fastening consists of a corner that is fixed to one side with a Mauerlate, and on the other side has a special slit-like lug. It establishes a metal loop with holes for fastenings to the rafters. Thanks to the free, not fixed vertical side of the corner, the mount gives the possibility of the rafter to be displaced several times, , causing a deforming effect on the walls of the building.

• The open fastening is arranged in the same way, and differs only in that the metal hinge is not inserted into the eyelet, but simply the upper part of the vertical shelf of the corner is folded down after installation, thereby fixing the connection.

Video: an example of installing a movable mount on the rafter and Mauerlat

2. Species hard mounts - much more. They are chosen depending on the massiveness of the wooden elements of the structure and the way the rafters are installed on the Mauerlat.

This includes metal corners of various sizes, LK mounts, which securely fix the rafters, installed with the help of a notch, without damaging it with fastening screws or nails.

• LK mountings are produced in several dimensional variants, therefore they can be selected for any thickness of the bar or board. The thickness of the metal from which this fastening elements are made, is 2 mm, no matter what size nor had. Depending on the size, the fastening parts have a different designation.

Designation	Dimension in mm
LK-1L	40 × 170
LK-2P	40 × 170
LK-3L	40 × 210
LK-4P	40 × 210
LK-5L	40 × 250
LK-6P	40 × 250

It should be noted that these fasteners are suitable not only for connecting rafters on the Mauerlate - they are used for fixing the units of "beams overlap - Mauerlat".

The main advantage of this fastening details - is the maximum rigidity and the reliability of the connection of wooden elements.

• Fastening the rafters with with cutting on the Mauerlate using corners is carried out on both sides, which provides rigidity for .

There are corners designed to fasten the rafters without cuts .They have higher shelves and are screwed with a large number of self-tapping screws. They are made of metal thickness of 2;2.5 or 3 mm.

Designation	Dimension ( length, height, width, thickness of metal) in mm	Designation	Dimension ( length, height, width, metal thickness) in mm
Reinforced corner	105 × 105 × 90 × 2	Strengthened corner KP5	140 × 140 × 65 × 2.5
Reinforced corner	130 × 130 × 100 × 2	Reinforced corner KP6	105 × 172 × 90 × 3,0
Reinforced corner	105 × 105 × 90 × 2	Reinforced corner KP7	145 × 145 × 90 × 2.5
Reinforced corner	50 × 50 × 35 × 2	Reinforced corner KP8	145 × 70 ×90 × 2,5
Reinforced corner	70 × 70 × 55 × 2	Reinforced corner KPL1	90 × 90 × 65 × 2
Reinforced corner	90 × 90 × 40 × 2	Reinforced corner KPL11	90 × 90 × 65 ×2
Reinforced Corner KP1	90 × 90 × 65 × 2.5	Reinforced Corner KPL2	105 × 105 × 90 × 2
Reinforced Corner KP11	90 × 90 × 65 × 2.5	Reinforced Corner KPL21	105 × 105 ×90 × 2
reinforced corner KP2	105 × 105 × 90 × 2.5	reinforced corner KPL3	90 × 50 × 55 × 2
reinforced corner KP21	105 × 105 × 90 × 2.5	reinforced corner KPL4	70 ×70 × 55 × 2
Reinforced corner KP3	90 × 50 × 55 × 2.5	Reinforced corner KPL5	50 × 50 × 35 × 2
Reinforced corner KP4	70 × 70 × 55 × 2.5	Reinforced corner KPL6	60 × 60 × 45 ×2

On some corners, of the given in the table, it is necessary to say a few words in addition, as their description requires refinement:

- KR 11 and KR21 are advanced corners marked often, to K P1 and KP2 .In these elements there is a hole for the anchorage, which has an oval shape, which reduces the risk of the bolt in case of shrinkage of the structure.

- KR5 and KR6 are the angles used for fixing the elements to which a large load-bearing load falls. Angle of to To P6 also is equipped with oval hole, and it is recommended to use when creating a truss system in a new house that will still shrink. These models are in demand for the installation of structures that have a high weight.

- Angle to To M produced from perforated steel and used for fastening rafters with a large cross-section. Especially it is well suited for wooden buildings. This corner fixes the very construction elements reliably , and when it is used it is not required to cut the rafters into the - Mauerlat enough to cut the right angle first.

series

- Corner KMRP is used for fastening rafter system parts at right angles, including rafter with mauerlate. It also differs from ordinary corners with its outstretched hole, with which the can the displacement when shrinking without damaging the of the fastening bolt. It can be used in a design where one element can not be embedded in another.

KMRP corners are produced from steel with a thickness of 2 mm. Three versions are available:

Angle designation	Dimensions in mm
a	b	with
KMRP1	60	60	60
KMRP2	80	80	80
KMRP3	100	100	100

• Another option for fixing rafters on the Mauerlate is to install them between two boards cut under the defined by the angle, and in addition at the bottom of the fixedusing metal corners or LK mounts.

Such fastening of rafters gives good rigidity and reliability .This method is well suited in cases where the rafter needs to be fixed at the right angle, lifting it above the horizontal plane of the Mauerlat, but fixing it to the vertical outer side.

• The method of fastening the rafters to the Mauerlat, made of a bar not too large section. is carried out by reinforcement of the bar using wooden pads having the required thickness.

The pieces of boards are attached to the Mauerlat with nails or screws, in places where the rafter legs are installed.

In this case, cutouts of the required configuration and depth are made in the rafters. Reliable fixes the rafter's feet to the wall with a steel wire, which is fixed to the hammered steel crutch.

• In addition to the above-described fastening methods, the rafters are nailed to the Mauerlat with staples. It should be noted that this method is enough is distributed by and has been used for a very long time. With the correct attachment of these elements, the rafter system will last for many years.

Brackets can be of different size, they are driven in different places of connection.

• More one mounting element that is used as an auxiliary - is a perforated strip TM . Its is used to amplify the of the fastening node, if necessary, to fix it further.

comes to the aid. In some cases this element can be irreplaceable, therefore it also can not be excluded when installing rafter legs on the Mauerlat.

Next, the is advisable to consider the construction of rafter systems - so it will be easier to understand which attachments are more suitable for them and why.

Features of

rafters The rafters are selected depending on the location of the bearing walls of the building. Each of the systems has its own additional retaining or tightening elements.

Asphalt rafters

System with stitched rafters differs in that it has one or more reference points, except for bearing walls. In connection with the with this, with the of the side walls a significant part of the load is removed.

bulk partition. In the form of additional retaining elements, side racks and "tailstocks" are used, supporting the ridge and fastened to the joists. And the beams, in turn, simultaneously serve as tightening for the construction, and also facilitate the load from the rafter system to the bearing walls.

Asprofile rafters are fastened to the Mauerlat with sliding joints that can move when shrinking or deforming the walls, leaving the roof structure unharmed. This is especially important to take into account in new buildings, since any newly built building necessarily gives shrinkage due to temperature fluctuations and ground movements.

Hanging rafters

Hanging rafters are called due to the fact that they do not have other supports, in addition to two side bearing walls. It turns out that they seem to hang over the inner space of the structure. In this case, all the load from the structure of the roof frame falls exactly on the Mauerlat.

For fastening to the Mauerlat of the suspended rafters rigid fasteners with no degree of freedom of movement are used, as the frame structure has only two points of support.

The suspension system of the rafters is spacer, therefore it exerts great pressure on the walls.

To remove some of the load from the walls of the building, additional elements such as struts, "tailstocks" and bolts are used that pull the system to the ridge bar and evenly distribute the load to all walls. The crossbars are installed parallel to the joists and the rafters pull together. Without these additional details, the design can become an unreliable .

Calculation of rafters

To ensure that the roofing system was reliable and strong, in addition to the optimal method of connection, you need to choose the right step for the rafter feet. This parameter is selected depending on the size of the rafters( their cross-section and length between the support points), and also from the roof structure.

In this table, you can obtain information on the required parameters for mounting the robust truss system.

Step of rafters in mm	Length of rafter feet in mm
3000	3500	4000	4500	5000	5500	6000
600	40 × 150	40 × 175	50 × 150	50 × 150	50 × 175	50 × 200	50 × 200
900	50 × 150	50 × 175	50 × 200	75 × 175	75 × 175	75 × 200	75 × 200
1100	75 × 125	75 × 150	75 × 175	75 × 175	75 × 200	75 × 200	100 × 200
1400	75 ×150	75 × 175	75 × 200	75 × 200	75 × 200	100 × 200	100 × 200
1750	100 × 150	75 × 200	75 × 200	100 × 200	100 × 200	100 × 250	100 × 250
2150	100 × 150	100 × 175	100 × 200	100 × 200	100 × 250	100 × 250	-

Several rules for fastening the rafters to the Mauerlat

In order for the fasteners to be reliable , it is necessary to observe a number of rules that are provided for this process:

• If metal fasteners are used for fastening, they must be attached to the wooden connecting elements with the utmost care- quality screws of the required length.
• If the rafters fit the cuts into the in the Mauerlate, then the dimensions must be precisely verified. This will ensure the tight robust rafter installation in the prepared sawlog, which should have a depth of ⅓ mauerlat. However, it should be remembered that such a rule will be valid only if the Mauerlatt is made of a powerful bar having a cross-sectional dimension of at least 150 × 150 mm.

• To avoid weakening the Mauerlat, most often the cuts are made in the very rafter at the right angle, and then the knot is then fixed with corners. The saw should not in this case exceed ¼ of the thickness of the rafters. This fastening - rigid and can be applied in the suspended roofing system.

• rafter. When using bolts to fasten the rafters to slopes, tightenings and other wooden elements, you must always install a washer or metal plate on the bolt, to prevent the nut from being flooded into the wood and, consequently, to weaken the structure.
• Attaching the rafters to the Mauerlat only with nails or screws is considered as an unreliable , therefore it is necessary to use corners or other metal fastening elements of different configurations.

• When installing rafters on wooden walls, be it hanging or , a stratified system, it is recommended to fasten them to the Mauerlat with a sliding fastening, especially if the roofing material is sufficiently heavy.

Video : several examples of fixing rafters to Mauerlat

The construction of the roof will be strong and will last for a long time without deforming by a wide variety of external influences, if calculations of of all elements produce correctly , correctly select and correctly mount all fastening nodes.