Mortar and Grout: Inspecting for Grout and Rebar - After the Wall is Built

The inspector didn’t show up on the job but you kept building – now you are being told to tear down the wall because no one knows if the rebars are in the right place and if the grout is solid. What do you do now?

Luckily you have some nondestructive options for “post-construction inspection.” Some methods are very simple, while others are high-tech and require expensive equipment with experienced operators. If you hire someone to evaluate your wall make sure they have good masonry experience. Many test labs are used to scanning reinforced concrete and can get confused by all the complexity of a masonry wall.

Sounding (tapping on the wall with a hammer) can be used to find solid grouted cells and near-surface voids.
Sounding (tapping on the wall with a hammer) can be used to find solid grouted cells and near-surface voids.

If you have a good ear, sounding (tapping on the wall with a hammer) can be used to find solid grouted cells and near-surface voids. If you want to verify your findings, just drill a small hole to see if you hit solid grout or a void. Drill into mortar joints to simplify repairs.

A pachometer is used to find metals in walls.
A pachometer is used to find metals in walls.

A pachometer (fancy metal detector) is used to find metals in walls, including veneer anchors, rebar, joint reinforcement, conduit, pipes, etc. Pachometers used for scanning reinforced concrete are good at finding bars up to 5 or 6 inches deep in the wall. The more expensive pachometers can tell bar size and depth of bars within walls.

Surface penetrating radar is sensitive to metals and can also be used to find solid grout and voids deep within masonry walls.
Surface penetrating radar is sensitive to metals and can also be used to find solid grout and voids deep within masonry walls.

Surface penetrating radar is sensitive to metals (such as rebar) and can also be used to find solid grout and voids deep within masonry walls. Scanning is carried out by rolling a radar antenna over the wall and interpreting reflections from metals, grout, voids, and other internal anomalies.

Infrared imaging using an infrared camera is a quick way to locate grouted cells in masonry walls.
Infrared imaging using an infrared camera is a quick way to locate grouted cells in masonry walls.

If temperature conditions are right, infrared imaging using an infrared camera is a quick way to locate grouted cells in masonry walls. A temperature differential of 20 to 30 degrees from one side of the wall to the other usually gives good results. This image is of a partially grouted wall was heated by strong sunlight for about 3 hours. Grouted cells have high thermal mass and take longer to heat up than empty areas.

Using Respirators for Silica Exposure
July 2025

Some in the masonry industry have expressed interest in respirator use as protection from harmful exposure to silica. This topic is of paramount importance due to its impact on our workers and the serious health effects of silica exposure. For those new t

From Bikes to Buildings: The Importance of Embracing Rainscreen Wall Designs and the New Building Codes.
July 2025

Have you ever been asked to do a project over the course of your lifetime? For example, when my kids were little, my wife asked me to assemble their bicycles. So, I opened the box, dumped out the contents, and cast aside whatever I thought was unnecessary

Laying the Foundation for Growth: Concrete Masonry Checkoff Unveils Five-Year Vision for Industry
July 2025

The Concrete Masonry Checkoff (CMC) put the finishing touches on an ambitious five-year vision for the industry, targeting a 20% increase in market share, driven by increased demand for concrete masonry products. “This is about building exquisite, enduri

Five of the Seven Chimneys Have Been Saved: Project Chimney Update
July 2025

In the wake of the devastating January wildfires that swept through Los Angeles's Pacific Palisades, a remarkable preservation effort is underway, spearheaded by Project Chimney, an initiative led by Evan Hall, founding director of the non-profit House Mu