How to Patch Insulation Holes in Plaster Walls (UPDATED: April 2020)

Owners of older homes often find themselves getting in “behind the walls” to add improvements that weren’t part of the original construction.

While some of these upgrades required the removal of huge sections of plaster, smaller projects such as blowing in loose insulation usually call for numerous four inch round holes to be cut into the wall.

The problem with cutting into lathe and plaster is that in removing the lathe, you’ve lost the support that will hold your plaster repair patch in place.

Before you can re-plaster the opening created by the installation of your new insulation, we at The Swindon Plasterer, recommend that you should create a new frame work that will provide your plaster with grip.

These instructions will show you how it’s done…

Materials Required: Patch Insulation Holes in Plaster Walls

A small roll of galvanised wire mesh with a measurement of 1/4 square per inch.

Wire mesh is available at all hardware and Home Improvement stores.

Other tools and supplies you will need include some small gauge wire (crafting wire OK); wire snipping tool; dowels cut into 4-5″ sections; patching plaster; a one inch putty knife; broad knife; ruler; compass with pencil; and a piece of paper for creating a cutting guide for the mesh.

A Step-by-Step Guide: How to Patch the Insulation Holes…

Step 1: Measure the size of the opening to be patched.

Step 2: Use the compass and paper to create a circular pattern for the wire mesh. Your paper pattern should measure about 1.5 inches in diameter larger than the area to be patched.

Step 3: Place the pattern on a corner of the wire mesh. Using your wire snipping tool and the paper pattern, cut out a circle shaped piece of mesh

Step 4: Cut an eight inch piece of crafting wire. Loop it through the centre of the mesh, so that both ends of the wire are on the same side of the screen. For the remaining steps, these two wires must face outwards towards you.

Step 5: Place the circular piece of mesh directly over the area to be patched. Use your fingers to press the centre of the mesh into the opening. Continue pressing until the edges of the mesh have dropped behind the old plaster.

Step 6: Pull the wire towards you, stopping when the wire mesh is flush with the back of the old plaster. Wrap the ends of the wire around a section of dowel to create a handle.

Step 7: Before plastering, brush the edges of the opening to remove loose plaster, then dampen the edges with a spray mister. The moisture will help improve the adhesion of the patching plaster.

Step 8: Hold the mesh in place by firmly pulling the handle towards you with the left hand. Use to right hand to fill in the hole with patching plaster, working from the edges to the centre. Leave the area around the wire slightly lower than the edges to allow room from snipping the wire. Run the broad knife around the perimeter of the hole to make sure that the patch is flush with the existing wall.

Step 9: Let dry for 24 hours.

Step 10: Unwind the dowel and clip the visible parts of the wire. Apply a second application of plaster to fill in the area around the clipped wire. Use the broad knife to smooth out the patch so that it is level as the wall.

Step 11: Let dry another 24 hours, then lightly sand before applying a prime coat.