For many people, using their own terrace is simply part of using the garden from spring to autumn. But while the sun is generally welcome, too much can quickly spoil the joy of being outside. Parasols provide a remedy. These find a secure hold in ground sockets. You can find out how to properly set these ground anchors in concrete in our step-by-step instructions.
Step by step to the concrete ground anchor
Just as there is no such thing as one parasol, there is of course no one universal method of setting the parasol stand in concrete. While the screen size mainly affects the required foundation size, the design of the screen mount has a major influence on how the connection between the foundation and screen looks.
1. The vertical restraint
The common way of setting the rod of the parasol in a prepared sleeve is well known. From a static point of view, the force is transmitted here by what is known as clamping, i.e., essentially over the length of the umbrella shaft located in the sleeve. While temporary ground anchors can be hammered in or screwed in, a tubular sleeve is inserted directly into the foundation for permanent ground anchors. The screen can then be adjusted directly into this.
2. The point-like connection via screws
If, on the other hand, the parasol is not “stuck” into the ground, a solid anchor plate, similar to a post base, is concreted into the foundation instead. The base of the umbrella is then built onto this plate using screws. This method is mainly used for large-format umbrella constructions such as traffic light umbrellas that span terraces. Depending on the size and construction, type-related static calculations by the manufacturer are used as a basis, which provide very precise information on the size of the foundation and any reinforcement that may be required. In addition, individual ground anchors tailored to the specific type of umbrella are usually offered, regardless of which of the two variants is now used, the step-by-step implementation of the foundation construction, including the necessary tools and materials, is largely the same:
- Spade or pickaxe
- Tear-proof fabric tarpaulin
- Trowel or garden shovel
- Bucket or small concrete tub
- Spirit level
- Square timber, length approx. 1 to 2 meters (depending on the size of the foundation)
- Wooden stick with the same diameter as a parasol handle, e.g., broomstick
- Scraps of wood to put under
- Hammer, pliers, nails
- Drilling machine with metal drill, approx. 5 millimeters
- Ground sleeve or post support to match the existing or planned parasol
- Gravel or split as bagged goods
- Concrete, e.g., ready-mixed dry concrete for direct mixing with water, as bagged goods, also ensure that it is suitable for outdoor use!
- possibly: structural steel according to the specifications of the parasol system manufacturer
Determine the foundation size
Before the first groundbreaking ceremony, you should consider how big your foundation needs to be. This is the only way you can prepare and procure the work and the necessary materials accordingly.
1. “Commercial” parasols:
For the classic parasol from the hardware store or from the discounter, the manufacturers usually do not specify any foundation dimensions. The matching ground socket is also rarely included. Instead, you use standardized products that are suitable for a large number of umbrellas.
- Concrete cover around the sleeve at least 10 to 15 centimeters
- Foundation width of 40 x 40cm is usually sufficient
- Depth depends on ground socket, height of ground socket + 10cm
2. Large size parasols:
If, on the other hand, umbrellas with large spans and thus large forces are used, the manufacturer’s information on the dimensions of the foundations should be observed. At terrace-spanning systems can easily have dimensions of 1.00 x 1.00 m in order to create a sufficiently large mass and an adequate abutment for the screen.
- Width: as specified by the manufacturer
- Depth: usually at least 0.80m for a frost-free foundation
Note: Care and maintenance are often easier with large-format parasols, as they were designed for durability and provide for dismantling.
TIP: Strictly speaking, even with small parasols, a frost-free foundation, i.e. a foundation to a depth of around 80 centimeters, should be carried out. The problem with a floor that freezes in winter, however, is primarily the irregularity with which this happens. Flat foundations can be raised unevenly in case of doubt and then sink again later. As a result, the umbrella will be inclined in the future. In the case of small foundations, this risk is negligible, so that a significantly smaller depth can be aimed for.
Step 1 – The excavation
First of all, of course, it is a matter of making a suitable hole for the foundation, in which later concrete can be poured.
- Stake out the foundation evenly in all directions from the planned umbrella location
- Cut off the lawn and store it on the side in sod
- Loosen the soil with a pickaxe or spade and store on a fabric tarpaulin for later disposal
Step 2 – the preparations
Before the concrete is actually poured, a few things still need to be prepared. Incidentally, formwork for the foundation is not one of them. The concrete is poured directly against the ground, so that a good interlocking of the ground and foundation increases the possible power transmission.
- Cover the foundation base with 10cm split or gravel and level off the surface
- Provide the ground sleeve (if not available) at the lowest point with a hole for the rainwater to drain off
NOTE: Since the parasol and the ground socket are in the open, water can get into the ground socket when it rains. The sleeve is provided with a hole so that it can escape from there. The gravel packing under the foundation allows the water to drain and seep away. If the water drainage is not provided, rust or an undesirable biotope of bacteria, insect brood and other things can arise in the long run.
Step 3 (optional) – structural steel
If structural steel has to be built into the foundation, this is done now, i.e., before the umbrella stand is aligned.
- Insert steel in the foundation hole according to the manufacturer’s instructions
- Ensure that there is sufficient distance to the ground on all sides (at least 3 to 5 centimeters)
- Place small stones or pieces of wood underneath as spacers
- Knock at least two vertical steel rods along the steel grating or cage into the ground and attach the reinforcement to it with wire (buoyancy protection with Concrete)
Step 4 – Aligning the post base or ground socket
As the last step before pouring the concrete, the core, i.e., the ground anchor, is inserted and aligned.
With ground socket:
- Insert the wooden stick into the sleeve as a replacement for an umbrella
- Place the sleeve on the gravel bed and, if necessary, adjust the height by removing or adding gravel – the top edge of the sleeve is the same as the top edge of the lawn
- Place square timber next to the “umbrella replacement” over the hole
- Align the bar vertically on all sides with a spirit level and fix it to the squared timber
With screw-on anchor plate:
- Fix the anchor plate with nails through screw holes from below on the squared timber
- Place squared timber with anchor plate over the foundation hole and place in the middle
- Adjust the height using wooden supports and align horizontally on all sides using a spirit level
TIP: The longer the timber, i.e., broomstick and squared timber, the more precisely the anchor plate and ground sleeve can be aligned. While a deviation of 5 millimeters is easily overlooked at 50 centimeters, it has an effect of 2 centimeters at a length of 2.00 meters and is much easier to see!
Step 5 – concreting
Now the time has come, the foundation is created and the future position of the umbrella is literally poured into concrete.
- Mix concrete according to the manufacturer’s instructions, paying particular attention to the right consistency
- Pour concrete layer by layer into the foundation hole and repeatedly “shake” it with a stick
- Fill concrete up to 5 centimeters below lawn level and smooth the surface
- Cover the concrete with foil or cardboard and protect it from excessive drying from the sun and rain
- After a few hours, pour water over large-format foundation areas
NOTE: The purpose of vibrating the concrete is to bring air bubbles to the surface. If you remain in the concrete, voids are created which can reduce the resistance in extreme cases. Incidentally, you do not have to hit the concrete with force, a moderate movement with a stick up and down in the concrete is sufficient.
Now it’s done. You can usually remove the wooden structure above the anchor after a day at the latest. However, depending on the concrete used, it can take two to around 14 days to achieve sufficient strength to safely accommodate even large loads. Finally, you can cover the foundation with garden soil and sow new lawns, or you can replace the sod that you removed earlier. This makes your foundation almost invisible and blends in harmoniously with the garden. As soon as the sun gains strength, you can now simply set your parasol in the ground socket or screw larger structures onto the anchor plate.