The CLAYTEC clayboard is a dry lining board for internal use made of reed-reinforced

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1 5.2 Clayboards Wall construction Dimensions Article No. CLAYTEC e. K Viersen Issued Valid for 12 months, thereafter see The CLAYTEC clayboard is a dry lining board for internal use made of reed-reinforced 5.2 clay and is building board and clay plaster in one. Clayboards are suitable for cladding internal walls, for lining the internal face of timber constructions, for suspended ceilings and roof spaces. Their excellent sorption characteristics and the accompanying beneficial effect on the room climate, especially in combination with CLAYTEC clay plasters, make them a natural alternative to other drywall building boards. Clayboards are made of earths and clay, reed stems and jute as well as other organic and mineral additives. They are 20 or 25 mm thick and measure 1.50 m m. They are easy to cut, fix and build on and require no special tools. Clayboards can be used by professional drywall contractors and self builders alike. Clayboards also have excellent sound protection properties. Noticeable sound insulation improvements can be achieved with comparatively simple constructions. This also contributes to a healthy living environment. 1 Clayboard t = 20 u. 25 mm / Insulation 3 Supporting construction 4 Flax joint reinforcement tape b = 10 cm Clay fine-finish topcoat plaster t = 2 3 mm

2 Building materials Clayboards are 20 mm (CLAYTEC ) or 25 mm thick (CLAYTEC ) and are mounted on a supporting construction with clayboard fixing screws (CLAYTEC ). Joints between boards are reinforced with flax joint reinforcement tape, b = 10 cm (CLAYTEC ) or with a similar tape made of jute or fibreglass. Approximately linear metres of scrim tape are required per m². After applying reinforcement tape, the entire surface is plastered with a thin layer of clay fine-finish topcoat plaster (CLAY- TEC ). A 30 kg sack is sufficient for 5-7 m² at a thickness of 3 mm. Very smooth finishes (surface finish quality Q3) can be achieved using clay surface filler (CLAYTEC ). A 10 kg sack is sufficient for 20 m. For such applications, a fibreglass mesh (CLAYTEC ) is used across the entire surface. 3 mm 2 mm Per 30 kg sack Mortar coverage in m² surface area for different plaster thicknesses Supporting construction Supporting constructions for walls and ceilings lined with clayboard can be constructed as normal for drywalling. The distance between supports should be 37.5 cm (centres) for 20 mm and 25 cm clayboards on walls and ceilings/sloping roofs. The distance can be extended to 50 cm centres for 25 mm clayboards mounted on walls. Supporting constructions can be battens or studs, or metal studs such as the resource-efficient PRO- TEKTOR MAXI-TEC. The supporting construction should be constructed perpendicular to the longitudinal direction of the boards so that a 25 mm board spans three spaces (150/3 = 50 cm) and a 20 mm board spans 4 spaces (150/4 = 37.5 cm). Should the boards be mounted parallel to the supporting construction, for example between ceiling beams, the distance between supports should not exceed cm (=62.5 cm/2). Butt joints at the short end of the boards should be arranged to meet at the supporting construction. Boards that meet mid-way between supports should be secured as shown on the next page. The long sides do not need additional fixing. If the supporting construction is erected before the boards are delivered, take into account the dimensional tolerances of the boards. Clayboards should not be fixed directly to structural elements such as posts or rafters as movement in the structural frame can lead to cracks forming in the wall surface. Instead, a separate supporting construction should always be constructed. Surfaces that will be coated with a coloured clay plaster (for example YOSIMA clay design plaster), or will receive another kind of high-quality surface treatment need a particularly stable supporting construction. Wall Ceiling Clayboard 20 mm 37,5 cm 37,5 cm Clayboard 25 mm 50,0 cm 37,5 cm Spacing (centres) of the supporting construction for wall and ceiling lining Boards are mounted perpendicular to the supporting construction Cutting Cutting and fixing clayboards Clayboards can be cut using a jig-saw or hand-held circular saw. A hardened steel blade is recommended for circular saws. Oscillating cutting machines (e.g. a FEIN-MultiMaster) can also be used. Clayboards can be fixed to a wooden supporting construction with clayboard panel screws (CLAYTEC ), to metal stud profiles thicker than 0.7 mm with, for example, WÜRTH Febos window drilling screws mm (countersunk head, tapping screw thread, zinc-plated and blue passivated), to PROTEKTOR MAXI-TEC profiles with WÜRTH Assy 3.0, 4 30 mm or 4 35 mm. The screws should be tightened so that they are flush with the board surface or maximum 1-2 mm beneath. In bathrooms and other wet rooms, corrosion-free fixings must be used; zinc-plated screws and washers are not sufficient. Clayboards can be screwed through right up to the edge. Fixing 2

3 The board should be fixed at 3 points on each supporting batten with the screws about cm apart (centres). For a 20 mm thick board, 15 screws are required, for a 25 mm thick board 12 screws. Staple fixings with certified broad back staples b = 25 mm (for example Haubold BK 2550 C. Staple spacings between 50 and 100 mm, distance to edge > 20 mm, penetration depth > 20 mm). When joints between earth building boards do not meet at the supporting construction, a backing strip made of plywood (min. 8 cm wide, 10 mm thick) should be used to fix the free ends of the boards. The backing strip should extend behind adjacent panels and be screwed to them. Building boards are always mounted with staggered joints: vertical joints should not be arranged above one another (horizontal joints likewise when the boards are mounted vertically). The boards should be staggered by at least 30 cm, better cm. Horizontal and vertical joints should not line up with the edges of window or door openings; instead the boards should be cut into an L-shape. Joints between boards are not glued. Stapling Board joints mid-way between supports Staggered joints Do not glue joints Finishing The major advantage of drywall construction is that boards can be finished immediately. Gaps of greater than 1 mm that can be filled with clay topcoat fine plaster (granularity mm) should be filled with this mortar prior to applying scrim tape. To reinforce the board joints, the areas along the board joints are wetted with a fine spray of water or with a slurry of diluted clay fine-finish plaster. The flax textile mesh of the reinforcement tape is then applied to the still wet surface and fixed in place by brushing over with a slurry of fine-finish plaster. Care should be taken not to add too much moisture. The edges of the reinforcement tape should be worked in especially carefully. If using jute reinforcement tape, it must be applied in a thin bed of mortar and rubbed in as thinly as possibly. Every extra millimetre leads to an unnecessarily thick layer of finishing plaster in order to avoid the tape being visible in the final wall surface. For this reason, joint tape runs should not overlap where they cross each other, but be cut to fit precisely. The reinforcement tape allows the plaster to bridge the board joints, but cannot, or only to a limited degree, accommodate movement in the substrate. If the supporting construction is not entirely stable, a reinforcement mesh should be applied to the entire surface in the first coat of a two-coat application of clay fine-finish plaster. This is also strongly recommended when the surface is to be coated with CLAY- FIX coloured plaster finish, particularly as a layer of fine-finish topcoat plaster must be applied anyhow to equalise the surface s suction characteristics. Walls and ceilings coated with clay filler should be reinforced with fibreglass textile mesh. Before any subsequent layers are applied, the slurry or plaster mortar used to bed the reinforcement mesh must be fully dry. The entire surface is then carefully wetted. This prolongs the working time and improves the adhesion of the subsequent thin coat of fine-finish plaster. The application thickness of clay fine-finish topcoat plaster is 2-3 mm. This can be directly coated with a clay primer and CLAYFIX Clay Direct or with YOSIMA clay design plaster. The application of a clay surface filler is just sufficient to close the pores of the clay finefinish topcoat plaster and has a thickness of 0.5 mm. The surfaces can be sanded and then given a second thin skim coat. This corresponds to a surface finish quality Q3. A coarse clay topcoat plaster is not suitable for plastering clayboards. Information on internal plasters made of clay and their finishing options are given in 6.1. Joint reinforcement Full-surface reinforcement Allow to dry Lightly wet the surface Surface finish quality 3

4 Installations and fixings Services for gas, water and heating can be routed within the cavities of drywall constructions as usual. Openings for recessed electrical socket boxes can be cut with a conventional core drill. For better stability when boring several adjacent sockets, mount a pre-drilled strip of plywood on the reverse side of the clayboard. Pictures, shelves and the like can be fixed with screws and wall plugs (e.g. cavity anchors). For heavy loads such as radiators, hanging cupboards etc., a horizontal board or scantling can be integrated into the wall construction as a supporting construction. Installations Wall fixings Material properties and technical data Table 5.2.1: Full declaration and material values Full declaration of contents Dimensions Bulk density λvalue* µ-value* Earth, clay, perlite, reed stems, hemp, jute mesh, cellulose fibres, starch < 1% 150 x 62,5 cm x 25 mm (D25), 150 x 62,5 cm x 20 mm (D20) 700 kg/m 3 0,13 W/mK 18 * λ - and µ based on measurements for a D25 clayboard. The corresponding values given in the DVL Lehmbau Regeln (German earth building code) are: λ= 0,21 W/mK, µ= 5/10 Table 5.2.2: Sound insulation improvement and sound reduction index Rw for building elements made with clayboards* in db according to measurements undertaken by the SWA-Institut, Aachen, Germany (extrapolated from measured values and theoretical assumptions) Wall linings ¹ (improvement) Cavity, ~6 cm Cavity, ~8 cm Cavity, ~10 cm No infill Unfired bricks Insulation Insulating 8 8 (DF format) (N format) (2DF format) Trennwände 2 (R w ) Cavity, ~6 cm Cavity, ~8 cm 47(R w,p ) 46 (with DF format) (R w,p with NF format) 53 (R w,p ) 56 (R w,p ) *Values based on measurements for a D25 clayboard (09.002), also applicable for a D20 clayboard (09.004) 1 Clayboard with clay fine-finish plaster, cavity, wood-based board (e.g. OSB or similar) 2 Clayboard with clay fine-finish plaster, cavity, clayboard with clay fine-finish plaster ³ NF = Normal format ( cm), DF = Thin format ( cm), 2DF = Twice thin format ( cm) 4

5 Clayboard as sound insulation CLAYTEC clayboards are a simple means of creating partitioning walls and wall linings with excellent sound insulation properties. Test certificates are available on request. Fire performance The CLAYTEC clayboard D25 has been classified according to DIN 4102 as building material class B1 (difficult to ignite). A simple internal wall and a ceiling construction were tested and accorded fire resistance class F30. Test certificates are available on request. To achieve an F30 fire classification, the supporting construction and means of fixing also need to fulfil specific criteria. See the precise description in the test certificate. Please note: The information provided in this worksheet is the product of extensive experience of earth building work and the use of our products. Nevertheless, this technical information cannot be regarded as legally binding. These notes assume a sufficient level of craftsmanship skills and experience, and knowledge of the relevant building trades. The most recent valid edition of this worksheet is always available from www. claytec.com. Reproduction and publication of these notes or parts thereof is not permitted. Copyright CLAYTEC e.k. Figure 5.2.1: Mounting clayboards on the studs of a frontwall installation Figure 5.2.2: Clayboard lining of a sloping roof on a separate supporting construction of battens 5

6 Figure 5.2.4: Pre-wetting the joints between the boards with a fine water spray Figure 5.2.5: Applying a slurry of diluted Claytec fine-finish topcoat plaster Figure 5.2.6: Working in the joint reinforcement mesh taking special care to bed the edges Figure 5.2.7: Applying a fine filler layer to the entire surface with Claytec fine-finish topcoat plaster 6