The harness in the frame house is designed to ensure the joint operation of the main load-bearing structures. The lower one plays the role of a grillage with a columnar or pile foundation, and the upper strapping of an individual frame house takes on the function of a Mauerlat. Proper installation of these elements ensure high reliability of the building. Each species needs to be considered separately.
The lower harness of the house
The lower harness is most often a wooden beam with a cross section of 150 by 150 or 200 by 200 millimeters. The dimensions of the section can be selected by calculation, but they should not be less than the thickness of the walls of the building. The main function of the lower harness is to ensure the joint work of the detached supporting structures of the house, therefore, with a strip foundation, it is not needed.
The grillage can also be made of rolled metal, but this is usually prevented by the following points:
- the large dead weight of metal elements puts a high load on the foundations, which increases their cost;
- the difficulty of doing it yourself because of the large mass of products;
- high cost of steel compared to wood.
In addition, it is best not to combine wood with steel elements due to the difference in the physical properties of these materials.
When the strapping device can be neglected
In some cases, the device of the lower harness in the house will become an unnecessary event. These options include:
- arrangement of houses on strip foundations;
- construction using Canadian-American technology;
- frame and panel construction.
When building a house in the second case, SIP panels (sandwich panels) are used. The system involves quick assembly of the house by type of designer. The disadvantage of this technology is the inability to build a house with your own hands.
Harness Requirements
When doing DIY, carefully monitor the following points:
- quality of lumber (for supporting structures, softwood of the first or second grade is used, humidity according to regulatory documents should be 12%);
- compliance with geometric dimensions;
- reliable connection of all strapping elements, including high-quality fastening to the foundation elements;
- reliable waterproofing in the places of fastening of the binding to concrete or metal foundations;
- obligatory treatment with flame retardants (fire fighting compounds) and antiseptics (prevent the appearance of mold and fungus on the wood surface), which is carried out for each element separately before the start of installation work.
Material selection
As already mentioned, the lower trim of the frame house can be made of wood or metal. The tree is better suited, but when it is used, the choice problem again arises. There are two options for wood beams:
- solid timber;
- glued beam.
The second option is characterized by increased strength and the ability to use at high loads or spans. The price is higher than for a beam of a similar section made of solid wood. For the construction of a home with your own hands, the use of expensive glued wood is most often economically inexpedient, since for ordinary frame structures an ordinary beam is enough.
In the end, we can conclude that for the construction of an individual house, the best option would be a solid bar as a strapping.
Fastening the harness to the foundations
When the foundation of the house is made of concrete or brick, anchor fastening is used. At the stage of construction of foundations, they include anchor bolts with a diameter of 12-16 mm.
The length is selected so as to ensure sufficient fastening of the strapping beam. It should enter the wood by at least 8-10 cm, but it is better to provide for through fastening.
The timber can be fastened to piles through with bolts with a diameter of at least 12 mm. As the second version of the fastening elements, metal studs of the same cross section can be used. Fasteners are recommended to be treated with protective compounds to prevent corrosion.
Straightener joints
When doing DIY, it is necessary to ensure a reliable connection of the grillage at the corners, at the junctions of the external and internal walls. With a sufficiently large length of the building, the standard length of lumber may not be enough and a connection of the strapping beam along the length will be required. Connections can be made in the following ways:
- "In the paw" and "in the floor of a tree" suitable for extension of length;
- "dovetail" (the most tight, but difficult to perform) is suitable for adjoining the inner walls to the outer;
- Root spike best used for corners;
- Butt - the simplest type of connection, characterized by low reliability.
The length of the joints “in the paw” and “in the floor of the tree” is selected depending on the cross-section of the strapping beam. The size of the joint should be within 2-3 beam heights. For reliable fixing, additional use of pins.
Floor of a frame house
A rational and economical solution will be to use the lower harness as an element of the floor of the frame house. The beam plays the role of load-bearing beams, between which an effective insulation is laid. On top of the frame is mounted a pie on the first floor floor.
The required thickness of the insulation is taken depending on the area of construction. On average, its value is 150-200 mm. The calculation is carried out according to the joint venture Thermal Protection of Buildings.
Upper harness
This beam is necessary to evenly distribute the weight of the roof and the snow load transmitted by the rafters to the walls. To simplify the work with your own hands, the upper and lower strapping are made of the same material of the same cross section. Beams are bonded to each other in the same way as in the previous case.
Fastening the harness to the racks of the frame
Mounting can be done using notches or steel corners. When using the first method, it is necessary to calculate the height of the racks in advance, taking into account the cut.
In the strapping beam, special grooves are provided for each rack, and they must coincide with the grooves for fastening the racks in the lower harness. Additionally, the structure is fixed with nails. When fastening with your own hands using the corners of the rack, they are fixed with screws.
Attaching rafters to the upper harness
Mauerlat perceives vertical and horizontal load from the rafter system. He evenly distributes the horizontal to the walls. Horizontal load is a spreader.
Fastening is most often done by cutting. After that, the structure is additionally fixed with two nails on both sides. It may be possible to secure with corners.
When tying the frame structure with your own hands, it is mandatory to control the quality of the source material and the reliability of the joints.
This ensures reliability and durability of the structure. Subject to the technology, the beam will reliably connect all the stand-alone frame elements into a single solid system and ensure the stability of the wall racks and the even distribution of the load on the foundations from the house and on the walls from the roof.