Loads and load-bearing capacity of a raised deck terrace - what is worth knowing?

Different types of loads act on the terrace, which must be considered already at the design stage to ensure that the structure will not be damaged.

What is the load-bearing capacity of a terrace?

The load-bearing capacity of a terrace is the maximum load that the terrace can "carry" without damaging any of its components.

It is one of the key parameters determining the safety and durability of the entire structure. Proper system design must account for both live loads, point loads, and operating conditions.

Despite its lightweight construction, a raised deck system can transfer very high loads, but only if the pedestals are correctly selected and spaced.

If you want to learn the basics:

See also: What is a raised deck terrace

What loads act on a terrace?

During design, several types of loads that will affect the terrace must be considered:

Live loads

These include:

  • foot traffic
  • garden furniture
  • standard terrace use

Point loads

  • planters
  • pergolas
  • jacuzzis
  • heavy furniture elements
Terrace with light large-format pavers with lavender and vegetation.

Dynamic loads

  • movement of many people
  • moving heavy elements
Roof terrace made of composite with pergola roof.

Environmental loads

  • snow
  • wind
  • water

What does the load capacity of a raised deck terrace depend on?

The load capacity of the system does not depend on a single element; it is the sum of several factors:

  • pedestal strength
  • type of surface (pavers / boards)
  • pedestal spacing
  • quality of the substrate
  • correct installation

Each of these elements must be matched to each other so that loads are properly transferred from one element to the next.

See also: Substructure of a raised deck terrace - what does it consist of and how to design it?

Pavers on pedestals with a weight simulating the load. Wooden stairs and exotic terrace covered with snow in winter. Construction of a wooden terrace at a modern house in winter. Outdoor café on a wooden terrace next to an office building. Leisure zone on a raised deck terrace with gres tiles. Built-in garden jacuzzi on a wooden terrace surrounded by forest.

Load Capacity of Terrace Pedestals and Support Pads

Both pedestals and support pads are the primary elements that transfer loads.

Depending on the series:

  1. Support pads - support up to 1000 kg
  2. Pedestals from the SPIRAL series - support up to 2000 kg
  3. Pedestals from the STANDARD series - support up to 1000 kg
  4. Pedestals from the MAX series - support up to 1500 kg
  5. Pedestals from the CLEVER LEVEL series - support up to 500 kg
  6. Pedestals from the RAPTOR series - support up to 1000 kg
  7. Pedestals from the ALU series - support up to 3000 kg

However, it is worth remembering that the key factor is not just the parameter of a single pedestal, but the load distribution across the entire system. For residential terraces, a load of up to 500 kg per pedestal is usually completely sufficient.

Below is a video showing the strength of the pedestals:

Pedestal spacing, or the key to safety

Spacing of supports directly affects the load-bearing capacity and safety of the terrace.

Typical rules:

  • 60×60 cm pavers - supported at 4 corners
  • larger formats - additional supports in the middle and on the sides
  • thin or brittle pavers - additional support in the middle

In the case of heavy loads, the number of pedestals is increased, their spacing is tightened, or more durable pedestals are selected (e.g., pedestals from the MAX series).

Finishing the side of a raised deck terrace using an edge clip. Finishing the side of a raised deck terrace using an edge clip. Terrace pavers on Spiral pedestals with ballast.

Load-bearing capacity of the surface - pavers vs. boards

Although the pedestals are the main element carrying the loads, the upper surface must also be resistant to sudden dynamic loads.

Raised floor on adjustable pedestals for terrace pavers. Elevated terrace on pedestals with XPS insulation. Layout of terrace pedestals for ceramic and concrete pavers. Project layout and list of DD Pedestals terrace pedestals.

Gres / concrete pavers

Due to the material they are made of, they are significantly more susceptible to chipping or cracking. However, when choosing pavers from a reputable manufacturer, we can be sure that they will be resistant to compression, weather conditions do not affect them as much as they do deck boards, and they better retain their shape.

Nevertheless, they require proper, stable support so that the entire pedestal head adheres to the paver.

More here:

See also: Elevated terrace with ceramic pavers - 2 cm ceramic tiles

See also: Elevated terrace with concrete pavers - a durable solution for outdoor applications

Boards (WPC / natural)

Boards, in turn, are more exposed to weather conditions, but they work more flexibly, so they do not crumble or crack.

However, they require a substructure of joists that transfer loads to the pedestals.

We describe this topic in more detail here:

See also: Elevated terrace made of composite decking (WPC)

See also: Elevated terrace made of natural wood planks - the elegance of wood in a modern system

Laying light terrace pavers on support pads on a gravel base by the pool. Installation of concrete pavers on adjustable terrace pedestals

The Importance of the Substrate

Even the best system will not function properly without a stable substrate, which ultimately bears the loads.

The substrate must primarily be:

  • load-bearing and stable
  • evenly distribute loads
  • not subject to settling
  • not shift
  • be sufficiently hard
Wooden terrace in front of the house in the garden. Installation of composite joists on adjustable terrace pedestals.

Loads in commercial buildings

In public spaces, the requirements for load-bearing capacity are significantly higher, and an increased fire resistance class is often also required.

The loads should include:

  • intensive pedestrian traffic
  • high point loads
  • building standards

Regarding fire resistance - our series of pedestals from the ALU series has class A1, however, many pedestals from other series are also produced in the NRO series, with class B-S1D0.

See also: Raised deck terraces in commercial buildings

Most common mistakes

To prevent damage to the terrace, avoid:

  • excessive spacing of pedestals
  • not accounting for point loads
  • using components that are too weak
  • lack of a stable base
  • ignoring manufacturer recommendations
Modern rooftop terrace with a city view. Modern reception and concierge area in a commercial building.

Summary

The load-bearing capacity of a raised deck terrace depends on the entire system, not just one component.

The most important factors are:

  • proper selection of pedestals
  • correct spacing of pedestals
  • matching the surface
  • stable substrate
  • consideration of loads

A well-designed system allows for safely transferring both standard and very large loads for many years of use.

Advantages of raised deck terrace vs. glued terrace. Adjustable pedestal MAX for terrace pavers Moss and dirt in the gaps between terrace pavers. Installation diagram of pavers on adjustable pedestals. Stairs made of terrace pavers on finishing clips. Wooden terrace in the garden with an olive tree. Modern terrace with concrete pavers and garden furniture.