How to Fill Anchor Holes in Brick

In this Build It, Ask This Old House mason Mark McCullough teaches Kevin O’Connor how to patch holes in a tough surface.

Anchor holes in brick are more common than you might think. As Mark McCullough points out, they come from all sorts of sources: holiday lights, hanging stockings, exterior signs on commercial buildings, and even decorative elements around fireplaces. The good news is that with the right color-matched product—whether a pre-tinted putty or a custom-dyed mortar mix—most homeowners can tackle this repair themselves.

Pro Tip: Mark McCullough cautions that when mixing mortar with dye for color matching, thoroughness is essential: “If you don’t mix this stuff over and over and over, the dye clumps up and you’ll get a heavier set in certain locations.” He also advises being careful not to add too much water to the mix.

In the episode, Mark McCullough explains that there are two methods he really likes for filling anchor holes in brick. The first involves matching your brick color using a tinted putty that comes pre-colored—just add water. The second uses a standard mortar and sand mix with dye added to achieve the right color match. As Mark notes, color matching is a critical part of getting the repair right: “Because this is such a difficult task, it’s never gonna be perfect. So if I can’t get as close as I would like, I do have other methods that are gonna bring me closer to what I want.”

Steps for Patching Holes in Brick

1. Find a mortar mix or compound that matches the existing brick as closely as possible (an exact match isn’t likely)
2. Using water sparingly, mix the compound or mortar mix to a thick putty-like consistency. It’s better to add small amounts of water a little at a time than trying adding material to a wet mix.
3. With a bit of the compound on a trowel, use a hex key or something similar to pack small amounts of the compound into the hole until the hole is filled to be slightly proud of the brick surface.
4. Use a trowel to flatten the compound against the brick. Press down and use a small circular motion—don’t drag the trowel across.
5. Using a damp sponge, press the sponge against the patched hole and then lift it straight off the brick to mimic the rough surface of the brick.

Pro Tip: Before applying your patching compound, lightly dampen the inside of the hole and the surrounding brick with water. A dry brick will suck the water out of new mortar, causing it to crack rather than cure properly. A light spray or a pass with a wet brush is all you need—you don’t want standing water, just a damp surface.

While doing a patch job, you have to make sure that you push the mortar in as far as possible, because you don’t have the opportunity to lay a bed joint the way you normally would when building a wall. Also keep in mind that fresh mortar will appear darker than the surrounding brick—but after about 28 days when the mortar fully cures, it should blend in and match the existing surface much more closely.

Shopping list

• Mortar mix or putty
• Dye for mortar
• Sponge
• Bucket

Tools