A guide to buying plant protection grills

Buying Guide: How to Choose the Best Tree Guards and Protection for Street Furniture

In urban redevelopment projects, along tree-lined avenues, in squares, public parks and pedestrian areas, the presence of trees must be correctly integrated with paving and transit routes. tree-saving grids horizontal and vertical plant savers. These street furniture elements are designed to protect the base of the tree and the trunk from trampling, accidental impacts, and other stresses typical of public spaces. Horizontal grates also allow water to drain to the ground and help maintain a tidy environment around the trunk, while vertical guards act as a barrier against potential mechanical damage. The catalog of Holity.co.uk offers tree grates in cast iron, galvanized steel, painted steel, and Corten steel, available in square, rectangular, and circular configurations and in numerous sizes. This purchasing guide analyzes types, center hole sizing, materials, installation methods, accessibility requirements, and cost parameters to help designers, engineering departments, businesses, and public green spaces managers choose the most suitable model.

1. Types of protection: Horizontal flush grids vs. vertical tree guards

Tree protection can involve both the base and root area as well as the trunk. The most appropriate solution must be chosen considering the installation location, the intensity of pedestrian traffic, the presence of vehicles, and the tree's characteristics:

Horizontal Plant Protection Grids (Flush with the Floor): They are installed around the base of the tree and, when properly installed, blend in with the surrounding paving. The open structure helps protect the soil from direct traffic and allows water to reach the root zone. The grates can be used on sidewalks, squares, parks, avenues, and other public spaces. However, compatibility with vehicular loads must be verified on the individual product's technical data sheet and cannot be deduced from the presence of the metal structure alone.
Vertical Tree Protectors (Corsets and Trunk Protectors): These structures are installed around the trunk to reduce the risk of impact and damage from moving vehicles, bicycles, lawn maintenance equipment, and other stresses found in public spaces. The catalog offers steel or metal models with different configurations and heights, including versions approximately 1400-1500 mm high and more compact solutions. It's important to choose a protection that leaves the trunk the necessary space for growth and doesn't rub against the bark.
Integrated Systems (Horizontal + Vertical): In areas particularly exposed to impacts, it may be useful to combine a horizontal grid with a vertical trunk guard. Some vertical tree guards can be anchored to the ground or combined with a compatible base grid. However, not all models are designed to be directly connected to each other: before purchasing, it is therefore necessary to check the fastening methods, dimensions, and compatibility between the components.

2. Shapes, Geometries and Sizing of the Central Hole

The external shape of the grid must be chosen in relation to the paving and the urban furniture project, while the dimensions of the central hole must be evaluated considering the current diameter of the trunk and its development over time:

External Shape: Square vs. Round

Square (and Rectangular) Grids: They integrate easily with modular paving, sidewalks, squares, and paths made with pavers, slabs, or other geometric elements. The catalog includes numerous sizes, from compact 60x60 cm and 80x80 cm models to 100x100, 120x120, 150x150, and 200x200 cm grids, as well as rectangular configurations such as 162x122 cm and 202x122 cm. The correct size must be chosen considering the available space and the desired permeability around the tree.
Round / Circular Grills: They represent an alternative to square versions and can be used in parks, plazas, public gardens, and urban design projects where a circular shape integrates better with the paving. The catalog includes models with different diameters, from compact solutions of approximately 600-800 mm to versions measuring 1500 mm and beyond. In these cases, too, both the external dimensions and the central opening must be considered.

Center Hole Sizing and Choking Prevention

The central hole must leave adequate space around the trunk. Too little internal light can become insufficient as the tree grows, causing the trunk to come into contact with the grid. For this reason, it's important to consider not only the tree's diameter at the time of installation, but also its future growth, and to plan for periodic inspections.

Growth franc rule: As a guideline, it is advisable to provide a central hole with a sufficient margin compared to the current diameter of the trunk. A total clearance of approximately 100-150 mm compared to the trunk diameter It can serve as an initial reference, but the final sizing must take into account the tree species, age, growth rate, and expected maintenance. For trees expected to grow rapidly, more space may be necessary.
Inner rings and openings of different sizes: Some models are designed with central openings of different sizes or with modular elements that facilitate the adaptation of the grille to the floor plan. This feature can simplify maintenance over time, but it is not present on all models. It is therefore advisable to check the technical data sheet for the actual dimensions of the opening and whether it can be modified or enlarged.

3. Construction materials: Cast iron vs. galvanized steel and Corten

The material affects the weight of the grate, its aesthetics, its weather resistance, and its maintenance requirements. The choice must be made based on the urban context and the characteristics declared for the individual product:

Cast iron: It is one of the most commonly used materials for tree guards for squares, sidewalks, avenues, and public parks. The heavy weight of the products contributes to the stability of the structure, while the possibility of creating decorative elements allows them to be incorporated into both traditional and contemporary settings. The Holity catalog also includes models in G20 cast iron and items composed of multiple assembled sections. Cast iron can be treated with protective coatings and finishes; corrosion resistance, finish, and maintenance requirements must be assessed based on the specific product and installation environment.
Hot-dip galvanized steel: Steel allows for the creation of grilles with shapes, decorations, and openings, including laser cutting. Hot-dip galvanizing, when performed according to the product's specifications, protects the steel from atmospheric corrosion and can be combined with subsequent paint finishes. The catalog includes galvanized and painted steel grilles, some complete with a hot-dip galvanized frame. In particularly aggressive environments, it is still necessary to verify the protective cycle and maintenance conditions indicated by the manufacturer.
Corten Steel: It's used in projects where you want to integrate tree protection with an aesthetic characterized by the material's typical rusty brown tones. The Holity catalog features both products made of Corten steel and grates made of galvanized and painted steel with a Corten-like finish: the two solutions should not be confused. It's therefore important to check the product sheet to see if the product is actually Corten steel or a finish that mimics its appearance.

4. Installation guidelines, support frames and pedestrian accessibility

Correct installation helps ensure the stability of the tree grille, the safety of pedestrian routes and the protection of the tree. Installation methods, support frames and fixing systems may vary depending on the model and should always be checked in the product's technical documentation.

Use of a support frame: many professional tree grilles are supplied with a perimeter support frame or can be installed with a separately available frame. This provides a stable seating surface for the grille and helps achieve correct alignment with the surrounding paving. A support frame is not required or supplied with every model, so the manufacturer's recommended configuration should always be checked and the base prepared accordingly before installation.
Assembly of individual sections: many tree grilles consist of 2, 4, 8 or more sections, making them easier to install around existing trees. Depending on the product, the connection system may use brackets, screws, bolts or other fixing components. Only the components and assembly methods specified for the selected model should be used.
Preparation of the area around the tree: the ground beneath the grille should maintain suitable conditions for root development and allow effective water drainage. During installation, excessive soil compaction should be avoided, the grille should not exert pressure on the trunk, and soil settlement and tree growth should be checked periodically. Drainage layers and filling materials should be selected according to the site conditions and project requirements.
Pedestrian accessibility and safety: when a tree grille is installed along a pedestrian or accessible route, the design should minimise trip hazards and allow comfortable passage for people with reduced mobility, wheelchair users and people with visual impairments.
- Openings and slots: their size and geometry should minimise the risk of wheelchair wheels, walking canes, heels or other mobility aids becoming trapped. Where elongated slots are used, they should preferably be positioned across the main direction of travel.
- Flush installation: the grille should be properly aligned with the surrounding paving and should not create protruding edges, hazardous level changes or unstable surfaces. For installations in public spaces or accessible routes, the applicable national and local accessibility standards should also be checked.

5. Regulatory Framework: Load, Accessibility and Durability Checks of Materials

For supplies intended for public spaces, it is not correct to automatically assign the same standards or load classes to all tree guards. The required documentation must be identified based on the intended use, construction characteristics, and project or specification requirements:

Tree design and protection: The grid must be sized to allow the tree to grow without interfering with the trunk and must provide adequate space for water, air, and maintenance of the basal area. The UNI 11038 standard is not a standard for urban tree care and should therefore not be used as a reference for tree protection grids. For public procurement or landscaping projects, it is advisable to refer to the agronomic and technical requirements actually applicable to the project and the instructions of the appointed professional.
Classification of Loads according to the EN 124 Standard: The EN 124 series specifically concerns guttering and closing devices for manholes, drains, and inspection chambers and cannot be automatically applied to a tree protection grate. If a specific reference has actually been tested or classified according to this standard, the manufacturer's documentation must expressly indicate this:
- Class A15: Within EN 124 it identifies devices intended for areas used exclusively by pedestrians and cyclists, with a test load of 15 kN.
- Class B125: Within the same standard, it identifies devices intended for, among other applicable contexts, comparable pedestrian areas and parking lots, with a test load of 125 kN. These classes should not be assigned to a tree grate without a specific product declaration or certification.
Hot-dip galvanizing and eco-sustainability: For hot-dip galvanized steel products, EN ISO 1461 may be relevant when the declared treatment falls within its scope. Steel and cast iron are recyclable materials, but the percentage of recycled material, paint characteristics, absence of certain substances, and compliance with Minimum Environmental Criteria must be documented by the manufacturer and cannot be automatically attributed to all products in the category.

6. Dimensional Parameters and Economic Planning

The assortment available in the Holity.co.uk catalog includes numerous configurations for parks, squares, avenues, sidewalks, and other public spaces. At the time of review, the category includes over one hundred items and falls roughly into a price range between €105.22 and €2,343.00 + VATPrices, availability, and promotions may vary over time, so it's always advisable to check the updated product sheet.

Metric development and catalog shapes:
- Square and rectangular measures: Compact formats of 60x60 and 80x80 cm are available, numerous versions of 100x100, 120x120, 125x125 and 150x150 cm and models up to 200x200 cm, as well as rectangular configurations such as 162x122 and 202x122 cm.
- Diameters of the round versions: The catalogue includes various circular formats, from compact models with an external diameter of approximately 600-800 mm up to 1500-1520 mm grids and other intermediate sizes.
- Dimensions of the useful central hole: They vary significantly depending on the model. Openings range from approximately 200 mm in diameter to over one meter in diameter in the larger models, as well as versions with a square opening. The opening must be chosen considering the diameter of the trunk and its future development.
Breakdown of spending bands:
- Entry level (approximately €105.22 - €300.00 + VAT): It primarily includes compact and medium-sized cast iron grates, square and circular models, and some essential solutions for tree protection. This range includes, for example, 60x60, 80x80, and 100x100 cm grates with different central openings.
- Mid-range (approximately €300.00 - €850.00 + VAT): It includes numerous grates in cast iron, galvanized steel, painted steel, and Corten, as well as various vertical tree guards. Price is influenced by size, material, weight, decorative workmanship, frame, and construction complexity.
- Top of the range range (approximately €850.00 - €2,343.00 + VAT): It primarily includes large-scale grids and steel structures intended for more complex street furniture projects, with formats up to 200x200 cm or significantly larger rectangular configurations. The high price does not automatically imply a higher load class: any structural performance must be verified in the product's technical documentation.

Request a personalized quote on Holity.co.uk

Protect trees and integrate greenery into public spaces with tree guards available on Holity.co.uk. In the catalog, you can compare horizontal and vertical guards, square, rectangular, or circular models, and solutions made of cast iron, galvanized steel, painted steel, and Corten steel. Before purchasing, check the external dimensions, central opening, material, frame, and mounting options for each product.

Are you a landscape architect, an agronomist, a designer, a municipal technical office official, or do you need to manage supplies for public bodies and administrations? Request a personalized quote The Holity team can assist you in choosing the right size, materials, and configuration, and provide technical data sheets, information on installation systems, and available documentation for individual products. When submitting public tenders or specifications, it's advisable to check the certifications, performance, and requirements for each specific product beforehand.

Frequently Asked Questions (FAQ)

What is the fundamental difference between a horizontal plant guard and a vertical plant guard?
The horizontal trellis is installed around the base of the tree and helps protect the ground from direct traffic, while also providing water drainage and integrating the plant area into the surrounding paving. The vertical tree guard, on the other hand, is a structure that surrounds the trunk and protects it from potential impacts from vehicles, bicycles, garden maintenance equipment, or other stresses. The two types can be used separately or, when technically compatible, combined in the same project.

How do you calculate the correct diameter of the central hole of the grill so as not to damage the tree?
The hole must be larger than the current trunk diameter and must take into account the tree's future growth. As a starting point, a margin of approximately 10-15 cm from the trunk diameter can be considered, but this is not a universal value: species, age, growth rate, and expected duration of the installation may require larger openings. It is also advisable to periodically check that the trunk is not approaching the grid and intervene before any contact points arise.

Why might it be useful to install a tree guard with a subframe?
The frame creates a defined support for the grating and can facilitate proper alignment with the surrounding flooring, contributing to the stability of the installation. However, not all gratings require the same system: some Holity models include the frame in the delivery, while for others it is available upon request or not included. Therefore, it is necessary to follow the installation instructions for the specific model rather than considering the subframe mandatory for every grating.

What characteristics must the grid have when inserted into an accessible route?
Ministerial Decree 236/1989 establishes that gratings inserted into pavements must have a mesh that cannot be penetrated by a 2 cm diameter sphere; when the elements are parallel, they must also be arranged perpendicular to the direction of travel. The grating must be installed without creating obstacles or dangerous differences in level with respect to the surrounding pavement. When designing accessible routes, both the geometry of the openings and the correct installation of the structure must be considered.

When is it better to choose cast iron over galvanized steel or Corten?
Cast iron is often chosen for sturdy, heavy-duty grates intended for plazas, avenues, sidewalks, and traditional urban design. Galvanized steel, on the other hand, allows for easier workability, even with laser-cut decorative motifs, and can be further painted. Corten steel is particularly popular when the project calls for the characteristic rust-brown finish. The catalog also features galvanized and painted steel products with a Corten finish, which should not be confused with products made entirely of Corten steel.

How does the price range in the category (€105.22 - €2,343.00 + VAT) correlate with the dimensions and materials of the grill?
The price depends on several factors, including size, material, weight, aesthetic finish, number of elements, presence of a frame, and the complexity of the structure. The entry-level range primarily includes compact and medium-sized cast iron grates; the mid-range offers numerous models in cast iron, galvanized steel, painted steel, or Corten steel, as well as various vertical guards. Higher prices primarily concern large steel grates and solutions intended for more complex urban design projects. However, price and dimensions do not constitute a certification of load capacity, which must be verified separately upon request.