How to Use Plaster Arch Formers

Plaster arch formers consist of pieces of metal lathe or mesh panels that cover an opening in a wall. The arch formers consist of four pieces, two per each side of the opening in the wall. Some will have an extra piece or extender for wider openings. They can be installed on new wall beams or existing wall openings during your remodelling projects. Use plaster arch formers to create neat curved archways in your home.

Put on your safety goggles and face mask. Prepare the opening on the wall where you are going to install the arch by removing any paint, wallpaper and plaster down to the brick with an electric sander.

Position the arch former segment against the opening in the wall, so that it is snug and extending 1/2-inch up onto the wall on all sides. Nail the arch segments into the wall with the provided masonry nails. Position the nails 1 inch apart on the former.

Cut a 1-inch piece of galvanised wire tie with tin snips. Insert the wire at the ends of the arch pieces, right against the end of the wall with half of it sticking out. Press the arch against the wire with a pair of pliers. The wire will be a support link for the sections.

Place the connecting arch drywall bead between the right and left sides of the arch to join the pieces together. If your wall is less than 6 inches thick, use the provided Soffit and self-tapping screws to make the arch thicker. Do this by overlapping the provided Soffit pieces against the wall and securing them into it with the self-tapping screws, then place the arch segments over the Soffit and nail into the wall.

Add the other half of the arch formers to the other side of the opening in the wall in the same manner.

Cut another 1-inch section of galvanised wire tie. Insert the tie in between the two arch formers where they intersect, halfway up from the bottom of the formers. Twist the wire tie to secure it in place, then bend the ends down into an opening in the lathe with a pair of pliers. Do the same for the other corner of the arch.

Nail standard angle bead onto the vertical corners that lead up to the arch with galvanised masonry nails spaced 1 inch apart.

Install the PVC arch nosing. Place the end of the arch nosing at the bottom of the joint where the arch and the vertical corner angle bead meet. Run the arch nosing up along the arch, and press the ends into the arch forms with your thumb to snap them into place. Trim excess nosing with tin snips.

Apply a 1/4-inch thick coat of plaster to the arch former. Wait overnight for the plaster to dry into a rough hard surface.

Use a plaster float to add a 1/8-inch layer of the finishing plaster over the hardened metal lathing plaster and smooth it to a level even surface. Wait 48 hours for the plaster to dry before sanding and painting it.


Arch formers are not intended to bear loads. If you are making a new opening in your walls, you will need to install a lintel to bear the load of the ceiling or the arch will crack. Wear safety goggles and a face mask when sanding to protect yourself from plaster dust.

Things You'll Need

  • Safety goggles
  • Face mask
  • Electric sander
  • Electric screwdriver
  • Hammer
  • Standard vertical corner bead
  • Galvanised wire ties
  • Tin snips
  • Pliers
  • Hardwall/metal lathing plaster
  • Plaster float
  • Finishing plaster
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About the Author

Alexis Rohlin is a professional writer for various websites. She has produced works for Red Anvil Publishing and was one of the top 10 finalists in the 2007 Midnight Hour Short Story Contest for Rohlin holds a Bachelor of Fine Arts in English from Madonna University.