Clay Unit Masonry AHA (Activity Hazard Analysis / Job Hazard Analysis)
Updated 2026-06-23
A Clay Unit Masonry AHA (Activity Hazard Analysis / Job Hazard Analysis) is the plan that keeps the crew building clay unit masonry safe from the clay-unit cutting silica dust, from the masonry-wall stability and collapse, and around the mortar contact and scaffold access. Clay unit masonry lays fired clay masonry units in mortar — combining the clay-unit-cutting-silica-dust hazard, the masonry-wall-stability and collapse hazard, and the mortar-contact and scaffold-access hazard. This guide walks through building a Clay Unit Masonry AHA that names the clay-unit-cutting-silica-dust, masonry-wall-stability/collapse, and mortar-contact/scaffold-access hazards and assigns the silica, stability, and contact controls that hold up in the field.
Why clay unit masonry needs its own AHA
Clay unit masonry is the construction of masonry using fired clay units — clay brick, clay tile, and structural clay units — laid in mortar. This continues the unit-masonry cluster, focusing on clay units. The defining feature is the clay units themselves: fired clay is a hard, dense, high-silica material, so cutting clay units generates significant respirable silica (clay units have high silica content), on top of the standard masonry- wall stability, caustic mortar, and scaffold access. The hazards combine the clay-unit-cutting-silica-dust (cutting the fired clay units — the silica hazard (fired clay is dense and high in silica — cutting clay units generates significant respirable silica)), the masonry-wall-stability and collapse (building up the clay masonry wall — the wall-stability/collapse hazard (an unbraced fresh masonry wall can collapse, especially under wind)), the mortar-contact and scaffold-access (the caustic mortar and building from scaffolds — the contact and access hazards), and the material-handling/falling-material. The clay-unit-cutting-silica-dust and the masonry-wall- stability/collapse justify a dedicated AHA.
Breaking clay unit masonry into steps
The steps for a Clay Unit Masonry AHA follow the laying:
- Set up scaffold access and material staging
- Mix and spread the mortar (caustic contact)
- Lay the clay units in courses (handling)
- Brace the wall as it is built (wall stability)
- Cut the clay units as required (silica control)
- Manage the silica, stability, and contact hazards
- Point, clean, and cure the masonry
- Complete
Each step carries a hazard, and the clay-unit-cutting-silica-dust, the masonry-wall-stability/collapse, and the mortar-contact/scaffold-access are where the most significant risks concentrate.
The hazards step by step
Clay-unit-cutting-silica-dust
Cutting the fired clay units — the silica hazard (fired clay is dense and high in silica — cutting clay units generates significant respirable silica). The controls are silica control for cutting clay units (fired clay units are dense and high in silica, so cutting them (with a masonry saw or splitter) generates significant respirable silica — wet cutting, dust extraction, respiratory protection, per the silica standard's masonry-saw provisions), and the silica controls. The clay-unit-cutting-silica-dust is a defining hazard — cutting high-silica fired clay generates significant respirable silica. (These follow the silica fundamentals.)
Masonry-wall-stability and collapse
Building up the clay masonry wall — the wall-stability/collapse hazard (an unbraced fresh masonry wall can collapse, especially under wind). The controls are bracing masonry walls during construction (unbraced fresh masonry walls collapse, especially under wind — bracing per the requirements, exclusion zones behind a wall being built), and the wall-stability controls. The masonry-wall-stability/collapse is a defining hazard — unbraced fresh masonry walls collapse. (These follow the masonry-wall-bracing fundamentals.)
Mortar-contact and scaffold-access
The caustic mortar and building from scaffolds — the contact and access hazards. The controls are preventing skin contact with the caustic mortar (gloves, skin protection — cement burns), safe scaffold access (properly erected masonry scaffolds, fall protection), and the contact/access controls. The mortar-contact/scaffold-access is a defining hazard. (These follow the cement-contact and scaffold fundamentals.)
Material-handling/falling-material
The material handling and falling material (heavy repetitive handling of clay units and mortar, falling units/ tools) carries the handling/falling-object hazard. The controls are safe material handling and ergonomics, falling-object protection (toe boards, controlled access below), and the handling/falling controls. (These follow the material-handling and falling-object fundamentals.)
A simple Clay Unit Masonry AHA structure
| Step | Hazard | Control | Standard |
|---|---|---|---|
| Access | Fall | Set up scaffold access and material staging | OSHA 1926.451 |
| Mortar | Caustic | Mix and spread the mortar (caustic contact) | project |
| Lay units | Ergonomic | Lay the clay units in courses (handling) | project |
| Brace | Wall collapse | Brace the wall as it is built (wall stability) | OSHA 1926.706 |
| Cut units | Silica | Cut the clay units as required (silica control) | OSHA 1926.1153 |
| Point/clean | Contact | Point, clean, and cure the masonry | project |
Clay-cutting silica control and wall-stability/contact safety
A Clay Unit Masonry AHA centers on clay-cutting silica control and wall-stability/contact safety. The clay-cutting silica control addresses the high-silica fired clay — controlled by silica control for cutting clay units (wet cutting, dust extraction, respiratory protection, per the silica standard's masonry-saw provisions), since fired clay is dense and high in silica. The wall-stability/contact safety addresses the wall and the mortar — controlled by bracing masonry walls during construction (unbraced fresh walls collapse under wind) and preventing caustic mortar contact, plus safe scaffold access. And the material handling and falling material get handling and falling-object controls. An AHA built on clay-cutting silica control and wall-stability/contact safety, with handling controls, addresses the hazards that define clay unit masonry.
From the field: what actually goes wrong
In fourteen years across federal, heavy civil, and industrial projects, clay unit masonry lays fired clay masonry units in mortar, and it continues the unit-masonry cluster with clay units, whose distinctive characteristic is their high silica content. The clay-unit-cutting-silica-dust hazard is a primary defining concern — fired clay units (clay brick, structural clay tile) are hard, dense, and high in silica, so when they are cut to fit (with a masonry saw or splitter), the cutting generates significant respirable crystalline silica, more than some other masonry materials because of the density and silica content of fired clay. So silica control for cutting clay units (wet cutting to suppress the dust at the blade, or on-tool dust extraction, plus respiratory protection, per the silica standard's provisions for masonry saws) is a key control. Cutting fired clay is a real silica exposure, and the dense high-silica clay makes the dust control important.
The masonry-wall-stability/collapse and the mortar-contact/scaffold-access are the other defining hazards, and they are the shared unit-masonry themes. On the projects I have run, building up the clay masonry wall brings the same defining masonry-construction hazard as all unit masonry — a freshly laid, unbraced clay masonry wall can collapse, especially under wind loads, so bracing masonry walls during construction (per the requirements limiting unbraced masonry wall height, with exclusion zones behind a wall being built) is the critical control. And the mortar-contact/scaffold-access hazard is the caustic mortar (cement burns from skin contact — gloves and skin protection) and building from scaffolds (safe scaffold access with fall protection). The heavy, repetitive handling of clay units and mortar and the falling-material hazard round it out. The AHA built on clay-cutting silica control and wall-stability/contact safety is the one that protects the clay-masonry crew.
The bottom line
A Clay Unit Masonry AHA names the clay-unit-cutting-silica-dust, the masonry-wall-stability/collapse, and the mortar-contact/scaffold-access hazards with specific controls — silica control for cutting the dense, high-silica fired clay units, bracing masonry walls during construction (an unbraced fresh wall can collapse under wind), and preventing caustic mortar contact with safe scaffold access. The clay-cutting silica control and the wall- stability/contact safety are the defining concerns. The AHA that manages both is the one that protects the crew.
Frequently asked questions
Why is cutting clay units a significant silica hazard?
Fired clay units (clay brick, structural clay tile) are hard, dense, and high in silica, so when they are cut to fit (with a masonry saw or splitter), the cutting generates significant respirable crystalline silica — more than some other masonry materials because of the density and silica content of fired clay. Controls are silica control for cutting clay units (wet cutting, dust extraction, respiratory protection, per the silica standard's masonry-saw provisions), and the silica controls.
Why is masonry-wall stability a defining hazard?
Building up the clay masonry wall brings the same defining masonry-construction hazard as all unit masonry — a freshly laid, unbraced clay masonry wall can collapse, especially under wind loads. Controls are bracing masonry walls during construction (per the requirements limiting unbraced masonry wall height, exclusion zones behind a wall being built), and the wall-stability controls.
What mortar and access hazards apply?
The caustic mortar causes cement burns from skin contact, and building from scaffolds brings the fall hazard. Controls are preventing skin contact with the caustic mortar (gloves, skin protection), safe scaffold access (properly erected masonry scaffolds, fall protection), and the contact/access controls.
What is clay unit masonry?
Clay unit masonry is the construction of masonry using fired clay units — clay brick, clay tile, and structural clay units — laid in mortar. Because fired clay is dense and high in silica (cutting generates significant respirable silica), unbraced fresh masonry walls can collapse, and mortar is caustic with scaffold access, those hazards apply.
Related AHAs and JHAs
- Unit Masonry AHA — the general unit-masonry fundamentals
- Brick Masonry AHA — the brick masonry detail
- Glazed Structural Clay Tile Masonry AHA — the structural clay tile detail
- Masonry and Block Wall Construction JHA — the masonry-construction fundamentals
Written by Mustafa Tok, CSP, ASP, CHST — OSHA Authorized Outreach Trainer with 14+ years of international construction safety experience across federal, heavy civil, and industrial projects.