What You'll Need
Before you start, gather the following tools and materials:
- MgO boards (correct thickness for your application — typically 10mm or 12mm for interior walls)
- Tape measure, pencil, and straight edge
- Scoring knife or angle grinder / circular saw with a fine-tooth carbide blade
- Corrosion-resistant screws (stainless steel or hot-dipped galvanised, 25–35mm for 12mm board)
- Drill/driver
- Jointing tape and MgO-compatible jointing compound
- Safety glasses and dust mask (N95 recommended — MgO dust is an irritant)
- Level and chalk line
Step 1: Prepare Your Framing
MgO board can be fixed to timber or light-gauge steel framing. Ensure studs are plumb, straight, and set at consistent centres — 400mm or 600mm centres are standard. Any bowing or twisting in the framing will telegraph through to the finished wall surface.
Check that any electrical, plumbing, or insulation work behind the wall is complete before boarding begins.
Step 2: Measure and Cut the Boards
MgO board can be cut using two methods:
- Score and snap: Score deeply along your cut line with a carbide scoring knife (multiple passes), then snap over a straight edge. This works well for straight cuts on thinner boards (up to 12mm).
- Saw cutting: Use a circular saw or angle grinder with a fine-tooth blade for thicker boards or complex cuts. Always cut on the face side and support the board fully to prevent cracking. Work outdoors or in a well-ventilated area — fine MgO dust is generated during cutting.
Leave a 2–3mm gap at the floor and ceiling to allow for minor movement. This will be covered by skirting boards and cornice.
Step 3: Fix the Boards to Framing
Start from a corner or a plumb reference line. Fix boards with the long edge running vertically (parallel to studs) or horizontally depending on your project requirements — vertical orientation typically gives a cleaner finish with fewer horizontal joints.
- Fix screws at 200mm centres along edges and 300mm centres in the field (middle of the board).
- Keep screws at least 12mm from board edges to avoid cracking.
- Drive screws until the head is just flush or very slightly below the surface — do not overdrive.
- Stagger vertical joints so they do not align between adjacent rows.
Step 4: Tape and Joint the Seams
MgO board jointing uses a similar process to drywall, but use a jointing compound specifically compatible with MgO. Standard gypsum-based compounds can react with magnesium oxide compounds over time.
- Apply a first coat of compound over the joint, bed alkaline-resistant fibreglass mesh tape into it, and feather out the edges.
- Allow to dry fully (check manufacturer's recommended cure time).
- Apply a second coat, feathering wider than the first.
- Sand lightly when dry. A third skim coat may be needed for a very smooth finish.
Step 5: Prime and Finish
MgO board surfaces are slightly alkaline. Use an alkali-resistant primer before applying paint or other finishes. This prevents paint adhesion failures and colour bleed-through. After priming, the surface accepts most standard interior paints, tiles, and decorative finishes.
Common Mistakes to Avoid
- Using standard drywall screws — they will corrode over time due to MgO's chemistry
- Skipping the alkali-resistant primer before painting
- Over-driving screws and cracking the board face
- Using gypsum-based jointing compound — use MgO-compatible products only
- Cutting without respiratory protection
With careful preparation and the right materials, MgO board installs cleanly and produces a durable, high-performance wall surface ready for a wide range of finishes.