How to conceal a steal RSJ ceiling beam

Concealing a steal (rsj) beam

If you're not into a more industrial, "loft-style" look, read this guide on how to conceal rolled-steel joists (RSJs) in your ceiling.

Here are a couple of ways you could hide an rolled-steel joist (RSJ) in your ceiling:

Camouflaging the RSJ

  1. Protect your work area with a dust sheet.
  2. Choose the paint colour that's closest to your ceiling colour.
  3. Take a wire brush to remove any rust from the surface.
  4. Use a mild detergent on all exposed surfaces of the beam and let the surface fully dry before proceeding to the next step.
  5. Add a primer over the entire RSJ beam then use a metal primer that will prevent rust from forming and bleeding through the painted finish.
  6. Add a 2nd coat of primer after the 1st coat of primer has dried.
  7. Obtain a paint that is suitable for metal and add the first coat of paint colour on the RSJ beam. Use a roller to start with and finish off with a paint brush to cover hard-to-reach areas.
  8. Let the paint colour dry before applying a second and third coat of paint.
  9. Apply a final coat of polyurethane paint when the coats of paint have fully dried.




    1. Protect your work area with a dust sheet.
    2. Measure the height, width and length of the RSJ beam you intend to hide.
    3. With this measurement, purchase the plywood or plasterboard and timber strips from a DIY shop. For an RSJ over 3m (10ft) long, you might want to cut the lengths of plywood or plasterboard to a smaller length and fix them individually.
    4. Secure timber strips onto the ceiling on both sides of the RSJ beam. Drill screws along the nailer strips, at 305mm (12in) intervals.
    5. Screw three pieces of plywood or plasterboard to make an open encasement.
    6. Apply liquid nails or similar to the edges of the encasement.
    7. Lift the encasement to the RSJ with the help of another person, and press it firmly to the nailer strips.
    8. Skew-nail the encasement to the timber strips.
    9. Fill any nail holes with wood putty and let it dry.
    10. With a caulking gun, apply caulk paste along the edge between the ceiling and the box.
    11. You can at this point paint the box to the colour of your choice.
  2. Boxing the beam

    If you have several RSJs supporting your ceiling, your best bet might be lowering the ceiling to hide them, a project for another day.

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