Creating a shelter for a vehicle is not just a matter of comfort, but a necessity that extends the life of the body and protects it from aggressive environmental influences. Proper calculation of a carport allows you to avoid collapse of the structure under the weight of snow or gusts of wind, which is especially important in unstable climates. Mistakes at the design stage can cost expensive repairs or even complete replacement of expensive equipment.
Before purchasing materials, you need to clearly determine the type of construction that will be optimal for your site. There are single-pitch, gable and arched options, each of which has its own characteristics of load distribution. Engineering approach the choice of roof shape directly affects the stability of the entire structure and the amount of materials required.
In this article we will analyze key design aspects, from choosing a location to the nuances of attaching supports. You will learn how to correctly calculate the snow load and choose the section of beams so that your canopy stood for decades without the need for major repairs.
⚠️ Attention: SNiP and SP standards are regularly updated. Before starting construction, check the current snow and wind load coefficients for your region in official sources or contact relevant specialists.
Selecting a location and determining the dimensions of the structure
The first step in the design process is site selection. The place must be level, with solid ground capable of supporting the weight of the supports and the vehicle itself. If the soil is loose, additional strengthening or installation of a monolithic foundation will be required, which will significantly increase the project budget. Dimensions the future shelter should exceed the dimensions of the car by at least a meter on each side for comfortable entry and exit.
The standard canopy height usually varies between 2.3–2.5 meters. This is enough for most cars, crossovers and even small minivans. However, if you plan to park vehicles with a roof rack or a tall van here, the height should be increased to 3 meters or more. The width of the span depends on the number of cars: for one car 3–3.5 meters is enough, for two – about 6 meters, taking into account the central support or reinforced beam.
⚠️ Attention: Do not place the canopy in close proximity to trees. Falling branches can damage the roof, and roots can deform the foundation over time.
When determining the length of the structure, consider not only the length of the machine, but also the approach angle. If entry is only possible at an angle, the length must be increased so that the rear overhang of the car does not remain in the open air during rain. It is also important to provide free space for opening the doors and trunk without the risk of hitting support pillars.
Calculation of snow and wind loads
The most critical stage is the calculation of the loads that the roof will experience. In Russia and the CIS countries, the main document regulating these parameters is SP 20.13330 “Loads and impacts”. The snow load is calculated using a formula that takes into account the weight of the snow cover on the horizontal surface of the earth and the coefficient of transition to the roof. For different regions, this figure can differ significantly: from 80 kg/m² in the south to 320 kg/m² or more in northern latitudes.
Wind load also plays an important role, especially for lightweight structures with large windage. It depends on the height of the building, the type of terrain (open or closed) and the wind speed in the construction area. Aerodynamic coefficients allow you to determine how the wind will flow around the structure, creating zones of rarefaction or excess pressure. Ignoring this factor can lead to roof failure during a storm.
To simplify calculations, ready-made tables are often used, but for complex or large structures it is better to contact design engineers. They will take into account all the nuances, including the possible accumulation of snow in the recesses or at the junctions of the slopes. Reliability farms or beams are checked for deflection, which should not exceed standard values (usually 1/200–1/250 of the span).
Use online snow load calculators, but always round up to create a safety margin.
Choice of materials: metal, wood or a combination
The material of the supporting structures determines the durability and appearance of the canopy. Metal structures made from a profile pipe or channel are characterized by high strength and relatively low weight. They require regular anti-corrosion treatment, but last for decades. Profile pipe rectangular section is the most popular choice for racks and purlins due to ease of installation and good load-bearing capacity.
Wooden awnings look more aesthetically pleasing and fit harmoniously into the landscape of a suburban area, especially if the house is also built of timber. However, wood requires careful treatment with antiseptics and fire-retardant compounds. When exposed to moisture and temperature changes, wood can dry out or rot, which requires more frequent maintenance compared to metal.
Combined options, where the racks are made of brick or stone, and the roof is supported by a metal or wooden frame, combine strength and beauty. Brick columns are not afraid of moisture and corrosion, but require a reliable foundation. The choice of roofing material is also important: polycarbonate is light and transmits light, corrugated sheeting is durable and cheap, and metal tiles are aesthetically pleasing, but heavier.
Material cost comparison
A metal frame with polycarbonate is the “golden mean” in terms of price and quality. Wood may be more expensive due to the need for high-quality processing and selection of grade. Brick supports significantly increase the cost of the project due to the cost of work and foundation materials.
Table of sections and spacing of supports for various spans
To ensure the stability of the structure, it is necessary to select the correct cross-section of the support pillars and the pitch of their installation. Below is an indicative table that will help you determine the parameters for standard conditions. The data is relevant for structures up to 3 meters high and with an average snow load.
| Construction type | Span (m) | Pipe section (mm) | Post pitch (m) | Roof type |
|---|---|---|---|---|
| Single-pitch | up to 4 | 80x80x3 | 3-4 | Polycarbonate/profiled sheet |
| Single-pitch | 4-6 | 100x100x4 | 3-4 | Profiled sheet/Metal tile |
| Gable | up to 6 | 100x100x4 | 4-5 | Any type |
| Arched | up to 6 | 80x40x2 (truss) | 3-4 | Polycarbonate |
It is important to understand that the data in the table are averages. The actual cross-section depends on the specific snow load in your area and the height of the structure. The higher the pillar, the larger its cross-section should be for bending. Using pipes with a thinner wall thickness than recommended may result in loss of stability.
When choosing a material, pay attention to the quality of the metal. For load-bearing elements it is better to use steel grade St3sp or St09G2S. Wall thickness pipes should not be less than 3 mm for main supports and 2 mm for secondary sheathing elements. Saving on metal is unacceptable here.
Never use pipes with a wall thickness of less than 2 mm for load-bearing structures, even if the span seems small - this is a safety issue.
Step-by-step instructions for installing the frame
Installation begins with marking the territory and laying the foundation. For metal poles, they most often use concreting in drilled holes or installation on ready-made concrete blocks with anchor fastening. The laying depth should be below the freezing depth of the soil so that heaving forces do not push out the supports in winter.
After installing the vertical posts, you need to check their verticality using a level and plumb line. Any deviations at this stage will lead to distortion of the entire structure and problems during installation of the roof. Then the racks are tied with horizontal beams (purlins) that will hold the roof. The elements are connected by welding or bolts.
☑️ Checklist before roof installation
Assembling trusses or installing floor beams is the next step. If an arched structure is used, the arches are installed at a certain pitch and connected by longitudinal connections. For single-pitched sheds, purlins are laid with a slope of at least 5-10 degrees to ensure water drainage. All welds must be cleaned of slag and coated with a primer.
Roofing installation and finishing
The roofing material is laid on the finished sheathing. For polycarbonate, it is important to use special thermal washers that compensate for the thermal expansion of the material. The sheets are laid with a protective layer facing outwards (usually it is marked with film), and the joints are closed with connecting profiles. Tightness connections prevents leaks and dust from getting inside.
Corrugated sheeting or metal tiles are attached with self-tapping screws with rubber washers to the lower part of the wave. It is important not to overtighten the screws so as not to deform the metal and damage the seal. The overlap of the sheets should be one or two waves to prevent water from flowing in during slanting rain.
Finishing includes painting the metal frame, installing a drainage system and, if necessary, side windbreaks. High-quality paint will protect the metal from rust and give the canopy an aesthetic appearance. The drain will divert water away from the foundation, preventing it from washing away.
The nuances of working with polycarbonate
When drilling holes in polycarbonate, use a sharp metal drill bit and low drill speed to prevent the edges of the hole from melting or cracking. Remove the protective film only after completing all work.
Frequently asked questions (FAQ)
Is it necessary to make a foundation for a light polycarbonate canopy?
Yes, even light structures require a foundation. The supports must be firmly fixed to prevent the wind from shaking the structure. Usually it is enough to concrete the pillars to a depth of 50-80 cm or use ready-made concrete blocks.
What is the minimum roof pitch for a canopy?
For corrugated sheeting, the minimum angle is about 8-12 degrees, for metal tiles - from 14 degrees. Polycarbonate can be mounted on slopes with a slope of 5 degrees, but it is better to do more for self-cleaning of snow.
Is it possible to weld a frame yourself without experience?
Simple structures can be assembled yourself if you have the skills to work with a welding machine. However, for complex truss systems or large spans, it is better to involve professionals, as errors in welds can be critical.
How to calculate the amount of snow on the roof?
It is necessary to multiply the projected area of the roof on the horizontal plane by the standard weight of the snow cover for your region (can be found in SNiP or the Internet). The resulting value will give the approximate load in kilograms.