Application of ceramic tiles and natural stones on exterior façades PREPARING THE LAYING SURFACE
The walls suitable for covering are in concrete or in cement-based plaster. Direct application on any type of brick is not permitted. In general, the laying surface must be as flat and solid as possible. The plaster must have a minimum adhesion to the substrate of 1.0 N/mm²; it must be resistant to abrasion, free from cracks, efflorescence and dusty or flaking parts. Other finishes are not allowed on the plaster, such as renders, finishing plasters, paints, etc. The plaster can be trowelled but not scraped. The concrete substrate must be clean from oils and release agents and loose parts. Any gravel nests, irregularities or missing parts may be restored with RASOPLAN, RASOPLAN FLEX and RESISTO LEVEL renders or mortars such as RESISTO depending on the thickness and characteristics of the substrate. Any reinforcement rods exposed must be cleaned and passivated in advance with STRATO 4900 or STRATO AB or STRATO FER before being covered with compensated shrinkage mortar of the RESISTO series.
PREPARATION AND LAYING OF THE ADHESIVE AGENT (when using COVERCOL AB RAPID)
It is a two-component adhesive and needs to be mixed with the proportion of 15 kg of powder with 5 kg of latex, pouring the powder slowly and mixing with a low RPM mechanical mixer until you obtain a paste with no lumps. The adhesive must be laid correctly by spreading a contact smooth surface of the adhesive on the bottom, using the smooth stainless steel spatula. This achieves the best anchorage to the bottom; then one proceeds to spread the adhesive with a toothed trowel, fresh on fresh. Even the flip side of the tiles must be coated with the adhesive (double coating) so that the contact surface is 100% and to prevent any interstitial cavities that may cause damage due to water infiltration (freeze-thaw cycles) or the formation of condensation. For small sizes with surface = 50 cm², minimum consumption of adhesive is about 4 kg/m² using a trowel with 6×6 mm teeth. For laying sizes >50 cm² follow the table shown at the side.
LAYING THE TILES
The tiles are applied by exerting sufficient pressure to ensure good contact with the adhesive and by moving them in one direction so that 100% wettability is always achieved. It is essential to check the available laying time, before starting to position the tiles. If there are high temperatures and wind, do not spread the adhesive over an area of more than 1-2 m².
TILE JOINTS
Closed joint installation, i.e. with the tiles in continuous contact is not permitted. It is best to lay the tiles with joints of a minimum width of 4 mm to 10 mm for larger sizes. Lower tile grouting joint widths are allowed with glass mosaic panels, and this is generally of at least 2 mm. Grouting should be carried out at least 24 hours after laying the tiles. To obtain better adhesion and waterproofing, use two-component epoxy grout FUGOPOX COLOR AB. Alternatively use the single component high-adhesion, waterproof grout FUGOFLEX 2-12.
EXPANSION JOINTS
Fraction joints must be performed at least every 30 m², corresponding to horizontal joints at least every 6 m and vertical joints at least every 5 m. Outward or inward corners can be sealed using appropriate mastics, or by placing corner profiles with compressible materials incorporated. The top stop sections of the vertical surfaces must be protected with frames or cap strips in order not to allow the rainwater to infiltrate under the coating.