Terraces - installation methods
In the case of terraces, there are two installation methods - traditional (adhesive) and raised deck (laid on pedestals), which differ not only in installation technology, but above all in the behavior of the structure over the long term of use. The choice between these solutions should not be based on aesthetics, but on technical conditions, loads, weather conditions, and the expected durability of the system.
Differences in terrace construction
In traditional bonded terraces, the pavers are permanently glued to the substrate using adhesive mortars. After the tiles are bonded, the gaps between them are tightly filled with grout. The entire surface, including the paver, adhesive, grout, and concrete substrate, is inseparably connected.
Below, the terrace substrate is protected with two different materials - torch-on membrane (on the left) and liquid membrane (on the right)
Problems with glued terraces
The space under the glued paver must be completely filled with adhesive mortar. Any empty space can cause problems in the future. The entire surface then works as a closed, rigid layer system in which the paver, adhesive, grout, and concrete substrate are inextricably connected.
Furthermore, ceramic terrace pavers have a rigid structure, unlike the building, which constantly moves and settles over the years. Stresses develop in the paver layer that can lead to cracking of the porcelain tile and the grout between them. Ultimately, this leads to permanent destruction of the flooring:
In a raised deck terrace, the surface:
- rests pointwise on pedestals,
- is not permanently glued to the substrate,
- forms a system of freely laid elements.
Thanks to this, the structure does not directly transfer stresses between layers.
If you want to start with the basic definition of the technology and its applications, go here:
Weather Resistance
Moisture constantly present in the atmosphere as well as temperature changes (sun / frost) cause water to accumulate in the gaps left between bonded pavers (vapor condenses).
Over time, accumulated water expands in volume under the influence of repeated freezing and causes irreversible damage. Pavers detach, grout crumbles, and the entire flooring needs to be replaced. This is one of the most common causes of failures in bonded terraces – water becomes trapped in the structural layers and has no possibility of freely evaporating.
In a raised deck terrace, water flows through the gaps between pavers directly to the waterproofing layer from which it is drained. In this system, we do not use adhesive or mortar, so water has no possibility of penetrating deep into the structure. The ventilation space beneath the pavers enables air circulation and accelerates the drying of all terrace layers.
The width of the gaps between pavers matters for water drainage and the movement of materials. More:
→ See also: Gap or joint on an external terrace - how to choose the right width?
Durability and strength over the years
In the case of a traditional terrace, if water penetrates deep into the structure, the only thing we can do to repair the flooring is to replace all materials - the entire existing flooring. Leaving a damaged glued tile floor for a longer period generates extensive damage. In the long run, it leads to permanent damage to all layers of the terrace. In such a situation, repair involves removing and replacing each layer of the flooring/ceiling: tiles, adhesive mortar, waterproofing, and drying the concrete layer. In practice, this means very high costs and a long period of the terrace being out of use.
In a raised deck terrace, the lack of permanent connections means that the surface can work independently of the substrate, which significantly extends its lifespan.
Below we present an example of a terrace covered with tiles fixed to the substrate with adhesive. However, after some time of use, the flooring was damaged. Despite the poor condition of the flooring, the terrace was successfully repaired, but it was done using a different method - a raised deck terrace.
Repair and revisions of the flooring
Both in the case of a raised deck terrace and a glued terrace, it is important to conduct systematic technical inspections of the terrace. If the repair of a glued terrace is carried out quickly after the damage occurs, it can be done under the aforementioned conditions. Only if water does not penetrate the lower layers of the ceiling is it possible to replace just the top layer. A glued terrace is a practically non-serviceable structure.
The biggest advantage of the pedestal technology is that at any time we can easily replace each paver individually. We can easily lift it, clean the substrate under the terrace, and lay it back in the appropriate place. A raised deck terrace allows point access to each layer of the system without destroying the rest of the surface - in the case of damage to one paver, we only replace that one paver.
If you are considering a terrace renovation (replacement of the surface without interfering with the waterproofing), see:
Differences in installation and maintenance
An adhesive-bonded terrace requires significantly longer installation time - primarily waiting for suitable weather conditions and drying. In contrast, laying pavers on a raised deck terrace is simple and possible in almost any weather conditions, even with high humidity. With this technology, we do not wait for mortar or adhesives to set. "Dry" installation shortens the construction time and significantly reduces the risk of errors.
If you are looking for step-by-step installation instructions (including construction details), see:
→ See also: Installation of a raised deck terrace - step-by-step instructions
Limitations of raised deck technology
In the case of raised deck terraces, we must ensure that the appropriate substrate rigidity parameters are maintained, and that point overloads are not allowed. By following the guidelines, the pedestals will not sink into the substrate over the years, and consequently, there will be no risk of damage to the terrace.
Remember not to place pedestals on unhardened ground.
A suitable substrate can be, for example:
- concrete screed with roofing felt (or without it if there are no rooms beneath the paver) - this is most common on balconies
- extruded polystyrene min. XPS200
- solid or open-cell concrete pavers
- concrete blocks
- or even old concrete sidewalk pavers, e.g., from demolition.
Comparison: glued paver terrace vs. raised deck terrace
RAISED DECK TERRACE vs. TERRACE WITH GLUED PAVERS
Installation time:
RAISED DECK TERRACE 1 day | TERRACE WITH GLUED PAVERS 4-10 days
Material costs for a 20 m2 terrace with 60x60 cm pavers (excluding labor days and pavers):
RAISED DECK TERRACE from PLN 720 | TERRACE WITH GLUED PAVERS PLN 350-1000
Possibility of using the surface immediately after installation:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - NO
Possibility of DIY installation:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - YES
100% resistance to freezing, water absorption:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - NO
Possibility of combining several types of pavers on one house terrace:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - YES
Possibility of replacing a single paver without damaging the remaining surface:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - NO
Terrace levels out substrate unevenness:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - NO
Hidden drains and installation under the terrace:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - NO
Flat usable surface after finishing:
RAISED DECK TERRACE - YES | TERRACE WITH GLUED PAVERS - NO
Possibility of installation in various weather conditions:
RAISED DECK TERRACE - YES | TERRACE WITH ADHESIVE-BONDED TILES - NO
No permanent connection between substrate layers:
RAISED DECK TERRACE - YES | TERRACE WITH ADHESIVE-BONDED TILES - NO
Long-term durability:
RAISED DECK TERRACE - YES | TERRACE WITH ADHESIVE-BONDED TILES - YES if bonded with extreme precision
Choosing a raised deck terrace protects the building and structural elements from penetrating moisture. It also offers simplicity and aesthetics - quick installation time of pavers with even joints and hidden installation elements. A raised deck terrace also provides the comfort of using a flat surface. Before starting the project, it is worth analyzing what matters most to us in order to make a good decision.
If you already know the practical differences between a raised deck terrace and a traditional adhesive-bonded terrace, the next step is to understand how exactly the raised deck terrace system works.
