Construction planning begins long before the purchase of the first pipe or sheet of corrugated sheets, because it is on paper or digitally that the future structure is born. Drawing of a garage made of metal profiles is the foundation of the entire project, determining not only the dimensions of the structure, but also its resistance to wind loads, snow and its own weight. Errors made at the design stage are almost impossible to correct without completely redoing the frame, so the creation of a detailed diagram must be approached with the utmost care and understanding of the physics of how metal works.
Modern technologies make it possible to create reliable car shelters using relatively lightweight materials, such as corrugated sheet C21 or H60, in combination with a profile pipe. However, the lightness of the structure does not mean that load calculations can be neglected, since the windage of walls and roofs made of thin metal is quite high. A well-drafted plan will allow you to accurately calculate the amount of materials needed, avoiding both shortages and unnecessary expenses on scraps, which often make up a significant part of the budget if not handled properly.
In this article we will analyze all the stages of creating working documentation, from choosing the type of foundation to the specification of bolted connections, so that you can independently develop or check the finished project. You will learn which nodes require reinforcement, how to correctly calculate the pitch of the racks and why it is important to take into account the wind rose in your region. The accuracy of metal cutting according to the drawing directly affects the tightness of corrugated sheet joints, which is critical for preventing corrosion.
Selecting the type of structure and dimensions of the building
The first step in developing documentation is to determine the functionality and dimensions of the future garage, since all further geometry of the frame depends on this. The standard solution for one passenger car is a span width of 3-3.5 meters, which allows not only to place the car, but also to ensure free exit from it with the doors open. If you plan to store spare parts, install a workbench or park a motorcycle, it is advisable to increase the width to 4 meters or more, which will require recalculating the load-bearing capacity of the trusses.
There are two main types of structures that are most often found in private construction: detached garages and home extensions. A detached building requires a full cycle of work, including the construction of four walls and an autonomous roof, which gives more freedom in choosing a shape, for example, a gable or shed roof. The extension rests on the existing wall of the building, which simplifies installation, but requires careful waterproofing of the joint and coordination of loads on the foundation of the main building.
- 🚗 A one-section garage is a classic solution for one car with minimal costs for materials.
- 🚙 Two-section option - suitable for a family with two cars or to accommodate a storage area and workshop.
- 🏠 Extension to the house - saves space on the site and simplifies the supply of communications, but requires attention to the load-bearing wall.
- 🚜 A garage with increased height is necessary for SUVs with expeditionary trunks or minibuses.
The height of the gate opening also dictates the overall height of the frame; standard gates have a height of 2.1–2.2 meters, but for comfort and installation of automatic systems it is better to lay 2.5 meters. During development drawing of a garage made of metal profiles It is important to immediately take into account the thickness of the insulation and internal lining if year-round operation is planned, so that the internal space does not become critically small.
Design of the foundation and lower trim
Metal profile is a lightweight material, but the windage of the structure and the need for rigid fixation of the bottom dictate their requirements for the base. Most often, for such garages, a shallow strip foundation or a monolithic slab is chosen, which provide stability and protection from ground moisture. At the drawing stage, it is necessary to clearly indicate the anchor attachment points, since their location must strictly correspond to the pitch of the vertical frame posts.
The lower trim is made of a larger cross-section profile pipe, usually 100x100 mm or 80x80 mm, and serves as the base for the entire frame. In drawings, this element is often designated as a “channel” or “I-beam” if rolled products of this shape are used, but a profile pipe is more convenient for joining with vertical posts. It is critically important to include in the project a waterproofing barrier between concrete and metal, usually a layer of roofing felt or bitumen mastic, to prevent capillary suction of moisture.
⚠️ Attention: Never attach a metal frame directly to concrete without waterproofing, even if galvanized metal is used. Capillary rise of moisture will lead to corrosion of the lower trim within 2-3 years, which will require expensive repairs.
When designing the attachment points for the lower trim to the foundation, you should use chemical anchors or drive-in pins with a diameter of at least 12-14 mm. The documentation must indicate the number of fasteners per rack; usually these are two studs at the edges of the pipe, which provides the necessary rigidity under wind loads. If the soil on the site is heaving, the drawing should include elements that compensate for soil movements, for example, sliding fasteners or reinforced reinforcement in the foundation.
Use a laser level when marking the foundation for anchors: a deviation of more than 5 mm over a length of 6 meters will make installation of the frame extremely difficult and require digestion of the nodes.
Frame diagram: racks, purlins and trusses
The load-bearing frame of the garage is assembled from a profile pipe of rectangular or square cross-section, the dimensions of which depend on the wind load in the region and the span of the roof. Vertical racks are usually made from pipes 80x80 mm or 100x100 mm, and their installation step varies from 2 to 3 meters, which is the optimal distance for attaching corrugated sheets. The horizontal purlins connecting the racks have a smaller cross-section, usually 60x40 mm or 40x20 mm, and are located in increments of 1-1.5 meters.
A garage roof made of metal profiles is most often made single-pitch for ease of installation or gable for better snow load and aesthetics. Roof trusses are calculated separately, and in the drawings they are shown as separate units indicating the angles of inclination and length of the elements. For spans up to 6 meters, triangular trusses made of 40x20 mm or 50x30 mm pipes are often used, where the upper chord experiences compression and the lower chord experiences tension.
| Frame element | Recommended pipe size | Installation step | Connection type |
|---|---|---|---|
| Vertical racks | 80x80 mm or 100x100 mm | 2.5 - 3.0 m | Butt welding or T-welding |
| Bottom/Top trim | 80x80 mm or 100x100 mm | Along the perimeter | Welding with gussets |
| Roof trusses | 40x20 mm or 50x30 mm | 2.0 - 2.5 m | Welding of node connections |
| Roof purlins | 40x20 mm | 1.0 - 1.5 m | Welding or bolts |
In the frame design, special attention should be paid to the gate opening, which is the weakest point of the structure. Gate opening pillars often require reinforcement with additional vertical elements or diagonal braces to prevent deformation when opening heavy doors. Usage stiffening braces in the plane of the walls and roof significantly increases the spatial stability of the entire building, turning a set of pipes into a single strong system.
☑️ Checking the frame drawing
Mounting points and specification of materials
The quality and durability of the garage directly depend on how the joints of the frame elements are designed. In modern construction practice from metal profiles, the welded connection dominates, which ensures the monolithic structure, however, for transportable garages or temporary structures, bolted connections on flanges can be used. In the drawings, each unit must be detailed: it must be indicated exactly how the pipes are joined (end-to-end, in a T-joint, with trimming), and what reinforcing elements (kerchiefs) are needed.
A bill of materials is a table that lists all profiles, their length, quantity and total weight. The presence of such a specification allows you to order metal exactly to size, minimizing the amount of waste, which when working with a profile pipe can reach 15-20%. When compiling a list of materials, it is important to take into account technological allowances for cutting and welding, especially for truss elements where the cut angles may not be straight.
⚠️ Attention: When designing bolted connections, be sure to indicate the strength class of the bolts (not lower than 8.8) and the need to use Grover washers to prevent self-unscrewing from vibrations.
To protect the metal from corrosion, the specification includes items on priming and painting. Often the drawings will specify surface preparation requirements such as degreasing and removing rust to a degree St3 according to ISO standard. High-quality anti-corrosion treatment included in the project will extend the life of the garage for decades, especially in an aggressive external environment.
Calculation of the weight of metal structures
The weight of one linear meter of a profile pipe 80x80x4 mm is approximately 9.3 kg. For a 6x4 meter garage you will need about 300-400 kg of metal just for the frame, not counting the roof and walls.
Sheathing with corrugated sheets and roofing
The final stage, which is also reflected in the working drawings, is the layout of the corrugated sheets. The sheets are laid with an overlap in one or two waves, depending on the angle of the roof and the type of profile, which must be clearly recorded in the documentation for the correct calculation of the amount of material. Wall corrugated sheeting is usually used for walls. S8, S10, S21, and for the roof - more rigid NS35, N60 or the same S21 with a reduced sheathing pitch.
The sheets are fastened with special self-tapping screws with EPDM washer, which are matched to the color of the coating. The roof drawings indicate the step of fastening the screws: in the plane of the sheet it is usually 2-3 waves, and along the perimeter and in overlap areas - in each wave. This ensures the tightness of the coating and prevents the sheets from being torn off by strong winds, which create significant lifting forces on flat surfaces.
- 🌧️ Overlap of sheets - with a roof angle of less than 12 degrees, an overlap of two waves and sealing of the joint is required.
- 🔩 Fastening step - at the ends of the building and along the ridge, self-tapping screws are screwed into each wave for reinforcement.
- 🌬️ The wind strip is a mandatory element that covers the ends of the roof and prevents the roof from being undermined.
- ❄️ Snow guards - necessary on metal roofs with a slope angle of more than 5 degrees for safety.
An important element of the drawing is the drainage diagram, including gutters and downpipes. Even for a small garage, organized drainage is important, as it prevents soil erosion around the foundation and splashes on the lower part of the walls, where the risk of corrosion is highest. Correct installation of the drainage system begins with the correct calculation of the slope of the gutters at the design stage.
Saving on the sheathing pitch or using too thin corrugated sheeting for the roof can lead to deformation of the sheets under the weight of snow, so strictly follow the calculated values in the project.
Typical mistakes when designing yourself
Independent development of drawings often leads to errors that become noticeable only at the installation or operation stage. One of the most common problems is ignoring the snow load characteristic of the construction region. A lightweight frame, designed without taking into account the weight of snow, can collapse in the first winter, so the use of current SNiP snow load maps is mandatory.
Another common mistake is the lack of diagonal connections in the plane of the walls and roof. A rectangular frame without braces is not a rigid system and can collapse like a house of cards in the event of a side impact or strong wind. Introduction to the circuit cross ties from reinforcement or profile pipe of small cross-section transforms the structure into a stable geometrically unchangeable system.
⚠️ Attention: Do not use pipes with a wall thickness of less than 3 mm for load-bearing elements of the frame, even if calculations show that 2 mm is sufficient. Corrosion and possible mechanical damage require a safety margin, which is provided by the wall of 3-4 mm.
They also often forget to provide technological openings for ventilation and installation of gates, which leads to the need to cut the already assembled frame, violating its integrity and anti-corrosion coating. All openings, lighting brackets and electrical supply points must be included in the drawing in advance. Careful elaboration of details on paper saves you from nerves and additional costs at the construction site.
Why does a new garage rust?
Often the reason lies not in the quality of the metal, but in the incorrect design of components where moisture and dirt accumulate, for example, horizontal shelves of profiles facing upwards, without holes for water drainage.
Is it necessary to make insulation in a metal profile garage?
Insulation is necessary if you plan to work in the garage in the winter or store temperature-sensitive materials there. Metal has high thermal conductivity, so without insulation (mineral wool, polystyrene foam, PIR boards) it will be cold inside, and condensation will form on the walls, causing corrosion of the car.
Which foundation is better for a 6x4 meter garage?
The best option is a monolithic slab 15-20 cm thick, which also serves as a floor. It evenly distributes the load and protects against rodents. A strip foundation is cheaper, but will require a separate floor and may be subject to movement on heaving soils.
Is it possible to assemble a garage from metal profiles without welding?
Yes, prefabricated bolt-on garages exist. They are more convenient to transport and install without special equipment, but require more precise manufacturing of parts and regular checking of bolt tightness. The welded version is stronger and more durable, subject to high-quality anti-corrosion treatment of the seams.
How to calculate the amount of corrugated sheeting for a garage?
You need to calculate the total area of the walls and roof, then divide by the usable area of one sheet (taking into account the overlap). It is recommended to add 10-15% of the margin for trimming and scrap, especially if the roof has a complex shape or has many junctions.
Is a permit required to build such a garage?
According to the legislation of the Russian Federation, a garage for personal use that is not used for business activities and is not a permanent structure (or stands on a foundation that does not require registration under the new rules) often does not require permission. However, the rules may change, and before construction it is worth checking the information with the local administration or MFC.