Designing a raised deck terrace - key principles and guidelines : Solver

Raised deck terrace - what makes it stand out?

Designing a raised deck terrace is a stage that determines the durability, functionality, and safety of the entire structure. Proper planning of layers, slopes, loads, and details helps avoid costly construction errors.

Unlike traditional glued systems, a raised deck terrace requires a systematic approach—every element of the structure must be consistent with the others.

terrace pedestal or support pad
surface layer - paver or joist with boards
gap through which water is drained
waterproofing
load-bearing layer or ground

If you want to learn the basics:

Where to start designing a terrace?

Designing should begin with an analysis of conditions, such as:

type of substrate (ground / concrete / roof)
available construction height
drainage method
expected loads
intended use of the terrace

Based on this, the type of pedestals and their layout are selected, as well as the type of surface that will be used.

Slope and water drainage

One of the most important elements of the design is proper drainage.

The correct slope is at least 1.5-2%, i.e., 1.5 - 2 cm per every 100 cm. In a raised deck terrace, the slope is created in the base layer so that the upper surface can remain level.

Water in the raised deck system:

flows through the gaps between the pavers,
reaches the waterproofing membrane,
is drained according to the slope.

System selection - pedestals and support pads

A key element of the design is selecting the appropriate system:

1) adjustable pedestals - for greater heights and uneven surfaces, for pavers and joists

2) support pads - for low-level construction, without adjustment, for pavers

The selection depends on:

the desired construction height
slopes
loads on the terrace
type of substrate
type of surface

Terrace pedestals and support pads described in more detail:

Pedestal spacing and load capacity

For a terrace with joists and decking boards, pedestal spacing of 40-50 cm under the joists is typically used.

For a terrace with pavers, pedestal spacing depends on:

1) paver format

2) paver thickness

3) anticipated loads

For the most commonly used 2 cm porcelain pavers, under standard load (without additional planters, very high foot traffic), the following spacing is assumed:

60×60 cm pavers - support at the corners (every 60 cm)
90x90 cm pavers - support every 45 cm, also in the center
60x120 cm pavers - support every 60 cm,

For both paver and decking board terraces, it is worth consulting the pedestal spacing with the manufacturer of the joists and the pavers.

In commercial projects, it is necessary to account for significantly higher foot traffic, and therefore greater loads.

Surface selection

It is worth analyzing what visual effect we want to achieve on the terrace, what budget we have, and how much time we will be able to devote to impregnation or cleaning.

On a raised deck terrace, a wide variety of surfaces can be laid, such as:

porcelain pavers
concrete pavers
stone pavers
composite decking boards (WPC)
natural decking boards
other materials - e.g. artificial grass grates, mosaic grates

If we want a natural, warm look, natural decking boards will be the best choice. However, they are expensive and require proper impregnation.

If we want a low price and quick cleaning - concrete or porcelain pavers will be a better solution.

Design details - key areas

Most problems often arise in unusual areas of terraces, such as:

door thresholds
roof drains
corners
terrace edges
expansion joints at walls
curves

These are areas that require special attention - it is worth designing them before starting installation. In the instructions, we describe the critical points of the terrace and how to solve them.

Terrace accessories can also be helpful, as they systematically solve many problems:

Wind protection

In designs of terraces on roofs, tall buildings, or in places where very strong wind gusts occur, the following should be analyzed:

wind suction forces
weight of the surface
method of additional securing of the pavers

Design and execution

The best design will not work without proper execution. It is very important to adhere to the design assumptions, as well as to use system solutions that have been specifically designed for this purpose. Using substitutes does not guarantee proper execution and can be risky.

The most common design errors are:

lack of slope or wrong drainage direction - the slope should be designed towards gutters, drains, or the ground
underestimating loads - analyzing whether heavy planters, pergolas, or jacuzzis will be placed
incorrect selection of system height - remember to subtract the height of the paver or board with joist from the total height (from the substrate to the planned top surface)
lack of expansion joints - expansion joints are necessary both between flooring elements and at walls
not considering details - lack of protection for terrace sides, stairs, or other elements

We describe the above issues in more detail here:

Summary

Designing a raised deck terrace is a key stage that primarily affects the durability of the structure and safety of use.

Proper terrace design eliminates most problems even before installation begins.

Thanks to a good design, installation will be much easier, and consequently, it will be easier to achieve an aesthetic and clean terrace finish that is easy to maintain.