Processing KLB decoration blocks
Creation of an optically elegant, practically mainte-nance-free wall surface
The 5 cm thick KLB decorative blocks are used to create claddings for room-side wall surfaces. KLB decoration blocks
- create an optically elegant, practically maintenance-free wall sur-face,
- improve the sound insulation and the room’s acoustic climate,
- improve heat protection,
- work as buffer for room humidity,
- and are not flammable including mortar (construction material class A1).
They consist of porous aggregate light-weight concrete as regulated in DIN 18152. The blocks in gross density class 0.60 and strength class 2 correspond to the octametric grid according to DIN 4172 with a joint width of 10 to 12 mm.
The cladding of wall surfaces on the room side does not affect public safety and order. No generally recognised rules of technology (standards, approvals) are required based on current, national understanding for manufacturing, application and execution. The main requirements that must be generally observed for finishing building materials and constructions are complied with in cladding with KLB decoration blocks.
KLB decoration blocks can be processed according to the construction principles of the national standards DIN 18515-1 “Exterior Wall Claddings; Mortared Tiles or Slabs” or DIN 18515-2 “Exterior Wall Claddings; Mortared Attachments on Standing Surfaces”. The decision about a principle depends on the building conditions. It is important that each of the principles is adhered to consistently. Replacing individual details leads to defects or damages in our experience.
Cladding may generally only be implemented if the materials used and the work area have a minimum temperature of + 5 °C. The weight of the cladding must be taken into account in the static calculations. This must in particular be observed when cladding for non-load-bearing interior separation walls is added afterwards.
Pursuant to DIN 18515-1 a lower standing surface is not considered in contrast to the other two standards. As these claddings are normally subject to the effects of weather and are exposed to wind suction, particularly high demands result for the cladding, the joint and setting mortar as well as the base. With exclusive room-facing cladding using KLB decorative blocks these high demands do not exist.
The cladding materials according to DIN 18515-1 are limited in their area (≤ 0.12 m²), side length (≤ 0.40 m) and thickness (≤ 0.015 m) and are characterised by a thick texture. In order to achieve sufficient adhesion between the cladding and the setting mortar, cement mortar is required for laying in the thick bed (d = 15 mm). It distinguishes itself by a high tendency towards shrinking. The setting mortar attaches each tile or panel independently, and there is no disc effect within the cladding layer. However, it occurs indirectly through the setting mortar layer, which is why movement joints become necessary at specific intervals within the cladding layer.
The requirements for the area (maximum 0.09 m²) and side length (maximum 36.5 cm) are adhered to by the KLB decoration blocks. While with a thickness of 5 cm they exceed the permitted thickness of 1.5 cm, they always have an area weight of tiles and panels of 30 kg/m².
Wall claddings mounted on the outside on standing surfaces are regulated in DIN 18515-2. The thickness of the cladding lies between 55 and 90 mm. It is directly exposed to the weather and is subject to wind suction. The resulting demands on cladding and joint mortar as well as the base are not present for room-facing claddings.
Anchoring working in the surface is implemented. The butt joint forces and compressive strength affecting the cladding are passed on through the shell joint to the underground. The anchorage can absorb tensile forces at any point of the cladding by means of suspended bracket loads, see DIN 4103-1.
While the cladding needs no standing surface according to DIN 18515-1, the standing surface required for the remaining processes must be able to take the load of the cladding itself. This means that requirements similar to those for a foundation must be set. The cladding is therefore placed directly onto the steel concrete ceiling. A floating floor or a wood beam ceiling as standing surface is not suitable.
For execution according to DIN 18515-1 the contact area must be such that it can take on the weight of the cladding itself. Chalk or gypsum plaster are not suitable for placement areas. The placement area must be free of dust, separation means, scum and contaminants.
Cladding is exposed directly to any occurring deformations of the base from e.g. shrinkage and crawling. A special tear bridging effect cannot be attributed to the cladding. Therefore the construction principle according to DIN 18515-1 is the preferred application for old buildings for claddings with KLB decoration blocks. It can be used for new construction if there is a sufficiently long period of time between completion of the shell construction and the attachment of the cladding. Just like with a plaster application, the time period should be at least 6 months.
Due to their porous aggregate structure and the favourable water retention ability, KLB decoration blocks display high bond shear strength and adhesive pull strength. For cladding according to DIN 18515-1, masonry mortar according to DIN 1053 is not suitable. Tile-setting mortar for the thin-bed and medium-bed process, which has improved adhesion, is suitable for this.
Grouting with a jointing iron cannot take place until the setting mortar has set sufficiently and is dried. For heated rooms or a medium temperature of approx. + 20°C this is generally the case after 7 days. For low temperatures the wait time must be increased appropriately, for a medium temperature of + 5°C to at least 28 days. Masonry mortar of mortar class II and IIa according to DIN 1053 are suited for the joint mortar. Mortar group III should not be used due to the strong tendency for the mortar to shrink. To guarantee a uniform appearance of the joints the use of KLB decorative joint mortar or ready-mix dry mortars is recommended.
The visible surface of the joints can be freely designed to a large extent. Due to the lack of weathering stresses, recessed joints can also be carried out.
Formation of the already laid block sliding, placed onto the mortar bed.
For cladding according to DIN 18515-2 use normal mortar of group II or IIa or the KLB decorative face masonry mortar. The construction principle requires a full joint execution of the butt and horizontal joints. Therefore smooth joint lines must be typically used.
The purpose of the shell joint is to transmit impact and pressure forces from the cladding to the substrate. Its thickness should be between 15 mm and 25 mm. It is filled with plastic mortar in layers.
Expansion joints in the masonry must be incorporated at the same location into the cladding. Additional expansion joints for claddings according to DIN 18515-2 are to be aligned at the vertical wall edges, at the upper wall edge and in the cladding surface at a distance L ≤ 2 ∗ H.
In particular for new construction, field limit joints become necessary in the cladding. According to DIN 18515-1 the horizontal and vertical distance of 3 to 6 m should not be exceeded.
The cladding has a tear-bridging effect, similar to the plaster layer. For reasons of tear safety, the limit recommended for the relationship of wall length to wall height should be maintained with L/H ≤ 2 in the dimensions. For reasons of tear safety of the cladding itself the overlap dimension of ü/h ≤ 0.4 must be adhered to.
Permanently elastic connection joints must be provided at connections between cladding and components with other deformation behaviour (window and door frames, wood, metal and plastic components). They should have a width of at least 10 mm. Fixtures, like windows and doors, must not be attached to the cladding. Attachments of heavy objects are as a rule only possible on the load-bearing base.
The cladding must be attached according to DIN 18515-2 with at least 5 wire anchors/m² with a diameter of 3 mm to the load-bearing wall. For room-facing cladding, according to DIN 18333 it is sufficient if the wire anchors merely have anticorrosive protection. Instead of the Z wire anchors other anchor types may also be used if they are able to take a tensile force of at least 1 kN with a slip of 1 mm at most.
In addition to the anchoring in the surface 3 anchors per m edge must be aligned along the free edges (openings, expansion joints, upper wall edge). As the anchors are only loaded in case of a pull, the anchoring occurs in the cladding in the front third of the cladding layer.