Gap or joint on an external terrace - how to choose the right width?

The choice of grout for an outdoor terrace depends on many factors - for a traditional terrace (with glued tiles), the choice of grout width ranges from 1 to 10 mm. For raised deck terraces, the matter is much simpler - we are guided by the material from which the paver is made - we have spacers available in widths of 3 or 5 mm.

If you want to learn the basic difference between these technologies, read:

→ See also: What is a raised deck terrace

Grout in traditional See also: Roof terrace - how to build a raised deck terrace step by step is a specially left gap between adjacent terrace pavers. It sets even spacing between the tiles - one from another.

The main task of grout is to compensate for thermal stress related to the expansion of pavers under the influence of temperature. Additionally, it should drain moisture from the substrate - so that it does not accumulate under the surface of the pavers.

More on structural and operational differences:

→ See also: Elevated terrace vs traditional glued terrace

See also: Elevated terrace vs traditional glued terrace

Types of grout and their thickness

There are many types on the market: cementitious grout, epoxy grout, and even recently popular - flexible grout (polyurethane). Each of them reacts differently to weather conditions and UV radiation.

Another important issue is the aesthetics that grout gives to the terrace through its width and color matching to the surface of the pavers (a completely different grout will be chosen for white ceramic tiles, and another for large-format natural stone slabs).

Although grout can be done from 1 mm, it is not recommended on outdoor terraces - this is due to the weather conditions that grout is exposed to (moisture, frost, sunlight), therefore on this type of terrace a minimum thickness of 3 mm is recommended.

The choice of grout width depends on: the size and material of the pavers, and the type of grout, below we show generally accepted values, however it is always worth checking the manufacturer's recommendations regarding the width.

Paver format and grout widths dependent on it:

30x30/40x40:

Cementitious 4 mm

Epoxy 3 mm

Flexible 3 mm

60x60:

Cementitious 4-5 mm

Epoxy 4-5 mm

Flexible 4-5 mm

80x80/120x120

Cementitious 5-8 mm

Epoxy 5-8 mm

Flexible 5-8 mm

Unfortunately, choosing too narrow grout, or its inaccurate execution leads to a number of complications

Unfortunately, the process of filling joints is often very problematic, and doing it incorrectly can have long-lasting consequences. Above all:

1. The grout used to fill the gaps must be made absolutely tight, while also being vapor-permeable - if water gets into the grout, or accumulates underneath, it will result in cracking of the pavers
2. During installation, specific temperature and humidity conditions must be met. The grout must set and harden in the right time, not too quickly but also not too slowly, and this is often difficult to achieve (especially in winter).
3. The grout must guarantee durability and resistance to weather conditions (watch out for discoloration from the sun, leaks due to expansion in winter, and compensation of paver stresses)
4. With traditional terraces, terraces are created flat (which causes standing water on the terrace) or with a slope, which makes the entire terrace surface inclined.

If you are interested in where standing water on terraces comes from, see:

→ See also: 5 reasons why water remains on the terrace after rain

See also: 5 reasons why water remains on the terrace after rain

With See also: Raised deck terraces – installation systems and technology for professionals, the gaps between the pavers are not filled, and therefore the entire grouting process is omitted. The spaces between the pavers remain empty.

With a raised deck terrace, the top surface can be completely level while the substrate is sloped — this, combined with the elimination of standard grout, allows for very rapid water drainage. Additionally, the empty spaces allow for free thermal expansion of the tiles and air circulation.

Additionally, the empty spaces allow for free thermal expansion of the tiles and air circulation. More about raised deck terraces:

→ See also: How does a raised deck terrace work

The spacer can be a built-in or additional part of the pedestal, and it creates an even gap relative to adjacent pavers. It is sometimes called a spacer leaf/butterfly, spacer insert, spacer, or shim.

Unlike traditional mortar joints, whose width is difficult to determine, raised deck terraces offer two widths to choose from—3 mm and 5 mm. They were designed specifically to easily and systematically set a specific gap width. Thanks to them, each paver is laid evenly (unlike with grouted joints, where widths often vary), and installation time is significantly reduced.

3 mm or See also: Joist adapter STANDARD h=28 mm Installing whole discs significantly speeds up the paver laying time.

For the STANDARD series, See also: Cross spacer 3 mm are dedicated, working similarly to [spacer discs.

In short, both the joint spacer disc and the spacer crosses can be described as 4 joint spacers combined into one element. This solution significantly speeds up the work. We don't have to make 4 movements to insert 4 separate spacer leaves - with one movement we have 4 gaps set. See how this speeds up the installation time:

Installing joint spacers on an adjustable terrace pedestal

In the case of adjustable pedestals from the See also: Elevated terrace vs traditional glued terrace, See also: Standard, and See also: Max series, the spacer widths are selected individually. When placing the order, we choose whether the joint spacers are to be 3 mm or 5 mm, and we receive them with the order. We can install them directly on the pedestal head as well as on the self-leveling head.

More about pedestals, heads, and accessories:

→ See also: Raised deck terrace system components

Are joint spacers visible?

In the case of raised deck terraces, you don't have to worry about which joint color to choose. Although the joint spacers are black, they are small enough that they are not visible.

Installed in a 3 or 5 mm gap, they become invisible. Their height is also small in relation to the thickness of the terrace pavers.