Appendix
HPL composite elements or HPL-Compact are suitable for wall claddings. HPL-Compact are available in different thicknesses and a minimum thickness of 6 mm is recommended (standard 8 mm), so that the sheets do not sag and adequate spacing for the fastenings can be selected. In rooms with increased moisture (spray water, steam, etc.), special measures for edge protection are required for HPL composite elements. Due to the response to moisture of HPL composite elements or HPL-Compact, these products should always be installed with rear ventilation so that they are exposed to the same climate on both sides. Depending on the building situation or application, the panels should be conditioned for a certain time before installation. HPL composite elements as well as HPL-Compact have different expansion properties lengthwise and crosswise and should therefore always be installed in the same direction.
Wall surface
The wall subsurface, especially fresh concrete walls, as well as brickwork and plaster, must be dry before installing any panels. The floor has to be strong enough to allow a solid connection to the substructure in order to absorb the weight of the panels and the distortion caused by climate influence.
Substructure
The substructure is required due to the different expansion behaviours of the wall materials and panels. This requires the substructure to be designed to let air circulate vertically. This is usually achieved with vertical battens of at least 2 cm thickness. Required horizontal battens have to be sufficiently interrupted to allow air circulation. Battens can be made from e.g. wood or sections of composite elements or HPL-Compact, or from metal profiles. Planed wooden battens with a cross section of 24 mm × 48 mm or 30 mm × 50 mm are often used. In most cases, it is practical to install a substructure of battens (horizontal or vertical) and counter battens. The counter battens are mounted on the first set of battens rotated by 90°. This makes it easier to obtain an evenly aligned substructure. Regardless of the structure, the surface of the battens has to form one level, using adjustment blocks if required to avoid unnecessary tensions. The substructure is fastened to the wall with suitable fasteners, e.g. screws and wall anchors. The fasteners have to be selected to suit the wall and the weight of the wall panels. In dry-wall constructions, the substructure has to be anchored in the profiles.
Fastening options for wall panels
The panels can be hung on the substructure, adhered invisibly or screwed / riveted on visibly
Hanging
The preferred method is to attach the wall panels by suspending them from the substructure, whereby vertical rear ventilation is ensured. The advantage of a hanging system is that the boards can be removed quickly and easily, which is important for expanding or adapting pipe and supply systems. It also allows the wall elements to be mounted without tensions. The panels can be suspended using Z-profiles made of metal (occasionally wood or HPL- Compact). Metal systems can be purchased from specialist retailers/stores. The number of suspension points results from the thickness of the panels and the application requirements. The structure has to be strong enough to bear the weight of the panels. The gap at the ceiling required for lifting and lowering the elements either remains visible as a shadow joint or is covered with a profile without impeding the rear ventilation.
Bonding
For bonded wall panels, vertical battens have to be attached for rear ventilation. The adhesive is applied vertically across the entire height. In addition to simple adhesive application, bonding systems with spacer tape (e.g. 2 mm thickness) are available to ensure that a minimum thickness of adhesive is applied throughout, allowing dimensional changes to be absorbed. Silane-modified polymer adhesives or PUR construction adhesives have proven successful as adhesives in this case. The technical data sheets from the adhesive manufacturers must be observed and, if in doubt, the adhesive manufacturer has to be consulted.
Screws, rivets
This visible installation method is not recommended for sophisticated wall panels for visual reasons. Direct fastening to the wall has to be declined.
Oval-head screws and countersunk screws are not suitable for direct fastening of the panels, unless appropriate washers are used. Screw and rivet heads should rest flush. Holes in the panels have to be drilled down to the attachment point, with a diameter approx. 2 mm larger than the screws (rivets), so the panels can react to climate changes. At the attachment point, the hole diameter corresponds to the screw diameter. The attachment point has to be placed as centrally as possible and is used for positioning the panels. The screws have to be applied in horizontal and vertical direction in a grid of 60 – 80 cm and only tightened finger-tight. The thicker the panels and the more balanced the climate in the panelled room, the larger the spacing can be.
The above instructions generally apply for installation with rivets. The rivet shaft should have a minimumdiameterof 5 mmand the rivet should be applied with a gauge, so that the tightening force is not too high and expansions of the panels due to climate changes can be absorbed.
Joints:
Lateral joints
Except for the visible fastening of the elements on the surface, it is important to install the edges securely. Loose or weak edges can result in the elements distorting along the longitudinal edges, which in turn leads to warping. There are numerous connection types and systems for implementing vertical and horizontal joints between the edges. It always has to be ensured that the joints provide the elements with room for expansion. The required expansion joints are dimensioned depending on the building situation and the sealing materials. The maximum width for installation without joints is approx. 3 m. On wall connections, the joint width should be at least 8 mm. Sealed joints have to be at least 5 mm wide. Adhesion along both flanks must be ensured. When working with sealing compounds, the technical processing information from the manufacturer has to be observed.
Corner joints
Corners and their secure fastening is of special importance for most wall panels. The elements forming the outer corners have to be securely fastened to the substructure and connected to each other so they can resist impact. For external corners, metal profiles are recommended for edge protection, especially on HPL composite elements. Compact formed parts or postforming elements are a good alternative. Depending on the structure, we recommend prefabricating corner elements. Sealed joints have to be at least 5 mm wide. Adhesion along both flanks must be ensured.
Ceiling connections
Ceiling connections of wall panels made of HPL composite elements or HPL- Compact always require a gap of at least 1 – 2 cm to ensure rear ventilation. Installation of the wall panels with suspension systems require a certain distance between the panels and the ceiling for attaching the panels. This gap can be concealed for visual reasons or expanded to accommodate ventilation screens
Bath connections
Tub and basin connections are subject to particularly intensive exposure to water. The prescribed sealing work therefore has to be carried out with particular care in this area. HPL-Compact is resistant to water and therefore particularly suitable for wet rooms. In addition, the installation and sealing instructions supplied by the manufacturers of the sanitary devices have to be observed and sealing compounds have to be used. Narrow areas (especially for HPL composite elements), cutouts and drilled holes have to be permanently sealed against moisture.
Floor connections
Depending on the subsequent intended use of the room, the wall panels can be joined to the floor in different ways. To ensure rear ventilation, a gap of at least 1 – 2 cm is required. If this is not possible for hygiene reasons, the gap can be extended to e.g. 10 cm. To protect the wall, a skirting board made from tile or a strip of HPL-Compact (e. g. 3 mm thick) should then be adhered full-surface using e. g. a universal silane-modified polymer adhesive. The skirting board has to be sealed against water towards the floor using a sealing compound. HPL-Compact is ideal for wall panels in wet rooms. If other materials are used, edges have to be protected against moisture.
Installation through or on the panels
In rooms with increased moisture, it is important that the structure is protected against water. As HPL-Compact has a high resistance to moisture, it is more suitable for these rooms than HPL composite elements. However, all openings in both variants have to be sealed appropriately. Different systems areavailableforthis, e. g. water pipe openings with special permanently elastic collars. Alternatively, the diameter of the hole is adapted so that a gap of at least 5 mm is created which can be filled with sealing compound. Cold water pipes in particular have to be insulated, as condensate could be generated which would damage the wall surface. The sealing work has to be carried out with great care as the quality and service life of the structure depend on them. Direct threaded connections into the panels have to be sealed with sealing compound and permanently elastic sleeves.
