10 MgO BOARD
Magnesium Oxide board should be stored in a dry, ventilated building, in a horizontal position, without contact with excessively humid surfaces. If the board is outdoors for some time (e.g. on sites), it should be stored under a shelter to protect it from direct rainfall. Carry the board in a strictly vertical position, avoid mechanical damage and soaking the surface. Wet boards must be dried before installation (visually inspect for a uniform, bright surface, without darkening). Before starting the installation, if necessary, cut the board with a knife or circular saw (jigsaw). If the surface of the plate is dusty, remove the dust.
For the inside fittings the mounting of a board should be carried out during finishing works (in wintertime with a heating system on), prior to finished floors in "normal" humidity conditions, when all the "wet" processes are done and the wiring of electrical and plumbing systems is completed. At the same time indoor temperature should not be below 15°C. Before installation MgO board should be adapted indoors (at least 3 days). The heating period is 4-5 days if the storage and transportation of the board were at temperatures below +5°C. Install only the dry board.
The vapour permeable properties of the material must be taken into account when installing the magnesia boards. Therefore, if the front side of the board is finished with a low vapour-permeability material, which prevents the absorption of water vapour from the surrounding air (ceramic tiles, vapour barrier paints, wallpaper, etc.), the back side of the board should also be given similar properties. For this purpose it is recommended to protect the back side of the MgO board with a vapour barrier film, fixing it on the frame, or to cover the surface and ends of the board with primers (paints) to form a vapour barrier film.
The distance between purlins for the profile system is based on the size, thickness of the board and the rigidity requirements of the finished construction. The thinner the board, the less the distance between purlins is. The main carriers are installed with 401, 481, 602 mm distance for wall cladding and partitioning. The distance of the supplemental carriers for the suspended ceiling frame is 401 mm. When using the board as the base for stone gluing, the distance between purlins narrows down to 301 mm, and for the floor base constructions, it is necessary to establish in addition lateral profiles with a step of 301-451 mm.
The MgO board should be fixed to the profile system (framing) with piercing or drilling self-tapping screws with a countersunk head (with notches on the conical part). Parts of the metal profile system and self-tapping screws must have an anti-corrosion coating, in addition thin-walled profile elements must be at least 0.55 mm thick. The installation of the plate to the frame must be carried out from the middle of the board to the edges. The step of the screws is 200-250 mm in the middle part and 150-200 mm along the perimeter of the plate, the distance from the edge of the board to the place of screwing is 15-20 mm.
For the inside works in dry and well-ventilated areas, the gap between the boards must be maintained between 4 and 5 mm, in wet areas and in outside it is 5 to 6 mm. The gap between the ends of the MgO board and the enclosure structures (in places adjacent to the floors, walls, ceilings) is 6-10 mm.
Before filling the joints and applying a leveling compound, the entire surface of the board and its ends should be applied with a primer (for example, Ceresit CT-17) two times, using the “wet on wet” method.
Fill the joints not earlier than 3 days after the end of the installation. Use the tape for reinforcement of the joints made of high-quality interlining or fiberglass and spackle. In rooms with “dry” and “normal” conditions, gypsum-based fillers modified with polymeric additives are used for sealing joints, for example: “KNAUF” - “FUGENFULLER”, “UNIFLOT”; "SEMIN" - SE-78, SE-86; Snowball - ACRYL-PUTZ ST10. For the “humid” conditions you need polymer-cement fillings as “Snezhka’s” ACRYL-PUTZ FD12. In rooms with significant fluctuations in temperature and humidity, to fill the joints between MgO boards and the wall, ceiling (along the perimeter of the connection), as well as on the facades, it is advisable to use permanently elastic polymer putty (e.g. "Fibrelastic" and "Sem Light" from the manufacturer "SEMIN".
Gypsum (gypsum-polymer) putties are used for full filling of the surface in rooms with "dry" and "normal" conditions, as for the "humid" ones - polymer and cement-polymer putties. For the filling on the facades of the building, only cement-based fillings with reinforcing additives modified with polymers are used. (e.g. Ceresit CT-225; ACRYL-PUTZ FD12 FASAD by “Snezhka” company).
It is recommended that the MgO board be painted with vapour-permeable paints that do not interfere with the free absorption and return of moisture (except as specified in §3)