Unit Masonry AHA (Activity Hazard Analysis / Job Hazard Analysis)
Updated 2026-06-23
A Unit Masonry AHA (Activity Hazard Analysis / Job Hazard Analysis) is the plan that keeps the crew building unit masonry safe from the masonry-wall stability and collapse, from the mortar caustic contact and cutting silica, and around the scaffold access and material handling. Unit masonry lays masonry units in mortar to build walls — combining the masonry-wall-stability and collapse hazard, the mortar-caustic-contact and cutting-silica hazard, and the scaffold-access and material-handling hazard. This guide walks through building a Unit Masonry AHA that names the masonry-wall-stability/collapse, mortar-caustic-contact/cutting-silica, and scaffold-access/material- handling hazards and assigns the stability, contact/silica, and access controls that hold up in the field.
Why unit masonry needs its own AHA
Unit masonry is the construction of walls and structures by laying masonry units (brick, concrete block, stone, tile) in mortar — the core masonry-laying activity, building up courses of units bonded with mortar into walls, partitions, and structures. This is the general unit-masonry AHA heading the specific unit-type activities (clay, brick, veneer, tile, terra cotta, concrete block) that follow. The defining feature is the masonry-wall construction: the critical stability of the wall as it is built (an unbraced fresh masonry wall can collapse, especially under wind), the caustic mortar and the silica from cutting units, and the scaffold access and heavy repetitive material handling. The hazards combine the masonry-wall-stability and collapse (building up the masonry wall — the wall-stability/collapse hazard (a freshly laid, unbraced masonry wall can collapse, especially under wind or before the mortar cures — the defining masonry-construction hazard)), the mortar-caustic-contact and cutting-silica (the caustic mortar (cement burns) and the silica from cutting masonry units), the scaffold- access and material-handling (building from scaffolds and the heavy, repetitive handling of units and mortar — the fall and ergonomic hazards), and the falling-material. The masonry-wall-stability/collapse and the mortar- caustic-contact/cutting-silica justify a dedicated AHA.
Breaking unit masonry into steps
The steps for a Unit Masonry AHA follow the laying:
- Set up scaffold access and material staging
- Mix and spread the mortar (caustic contact)
- Lay the masonry units in courses (handling, ergonomics)
- Brace the wall as it is built (wall stability)
- Cut units as required (silica control)
- Manage the stability, contact, and access hazards
- Point, clean, and cure the masonry
- Complete
Each step carries a hazard, and the masonry-wall-stability/collapse, the mortar-caustic-contact/cutting-silica, and the scaffold-access/material-handling are where the most significant risks concentrate.
The hazards step by step
Masonry-wall-stability and collapse
Building up the masonry wall — the wall-stability/collapse hazard (a freshly laid, unbraced masonry wall can collapse, especially under wind or before the mortar cures — the defining masonry-construction hazard). The controls are bracing masonry walls during construction (a freshly laid masonry wall is not stable until the mortar cures and it is braced — unbraced masonry walls collapse, especially under wind, so bracing per the requirements limiting unbraced masonry wall height, and a limited access/exclusion zone behind a wall being built or braced), and the wall-stability controls. The masonry-wall-stability/collapse is the primary defining hazard — unbraced fresh masonry walls collapse. (These follow the masonry-wall-bracing fundamentals.)
Mortar-caustic-contact and cutting-silica
The caustic mortar (cement burns) and the silica from cutting masonry units. The controls are preventing skin contact with the caustic mortar (gloves, skin protection — masons work with mortar constantly, and it causes cement burns), silica control for cutting masonry units (cutting brick/block/stone generates respirable silica — wet cutting/dust extraction, respiratory protection), eye protection, and the contact/silica controls. The mortar-caustic-contact/cutting-silica is a defining hazard — mortar is caustic and cutting units generates silica. (These follow the cement-contact and silica fundamentals.)
Scaffold-access and material-handling
Building from scaffolds and the heavy, repetitive handling of units and mortar — the fall and ergonomic hazards. The controls are safe scaffold access (properly erected masonry scaffolds, fall protection), safe material handling and ergonomics (the heavy, repetitive lifting of units and mortar — hoisting to the scaffold, staging, ergonomic management), and the access/handling controls. The scaffold-access/material-handling is a defining hazard — masonry is at height and heavy repetitive work. (These follow the scaffold and material-handling fundamentals.)
Falling-material
The falling material (units, tools, mortar from the scaffold/wall) carries the falling-object hazard. The controls are falling-object protection (toe boards, controlled access below, hard hats), and the falling-material controls. (These follow the falling-object fundamentals.)
A simple 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 masonry units in courses (handling) | project |
| Brace | Wall collapse | Brace the wall as it is built (wall stability) | OSHA 1926.706 |
| Cut units | Silica | Cut units as required (silica control) | OSHA 1926.1153 |
| Point/clean | Contact | Point, clean, and cure the masonry | project |
Masonry-wall stability and mortar-contact/silica control
A Unit Masonry AHA centers on masonry-wall stability and mortar-contact/silica control. The masonry-wall stability addresses the wall as it is built — controlled by bracing masonry walls during construction (limiting unbraced wall height, exclusion zones behind a wall being built), since unbraced fresh masonry walls collapse, especially under wind. The mortar-contact/silica control addresses the caustic mortar and the cutting dust — controlled by preventing skin contact with the caustic mortar and silica control for cutting units. And the scaffold access, material handling, and falling material get access, handling, and falling-object controls. An AHA built on masonry-wall stability and mortar-contact/silica control, with access controls, addresses the hazards that define unit masonry.
From the field: what actually goes wrong
In fourteen years across federal, heavy civil, and industrial projects, unit masonry lays masonry units in mortar to build walls, and it is the general unit-masonry AHA heading the specific unit-type activities in this batch. Its defining hazards are the core masonry hazards, with wall stability the one carrying catastrophic potential. The masonry-wall-stability and collapse hazard is the primary defining concern — as a masonry wall is built up course by course, a freshly laid masonry wall is NOT stable until the mortar cures and the wall is properly braced or supported, and unbraced masonry walls under construction can collapse, most dangerously under wind loads, which can topple a tall, freshly laid, unbraced wall and kill workers on or near it. Masonry wall collapse from wind on an unbraced wall is a recognized and repeated masonry-construction killer, which is why there are specific requirements limiting the height of unbraced masonry walls and requiring bracing. So bracing masonry walls during construction and keeping people out of the area behind a wall being built or braced (a limited access/exclusion zone) are the critical controls. The unbraced fresh wall's vulnerability to collapse is the defining unit-masonry hazard.
The mortar-caustic-contact/cutting-silica and the scaffold-access/material-handling are the other defining hazards. On the projects I have run, masonry is built on mortar, which is cement-based and caustic, and masons work with it constantly and in close contact, so prolonged skin contact causes cement burns (gloves and skin protection), and cutting masonry units generates respirable silica (the same high-silica cutting hazard as the concrete-cutting cluster — wet cutting or dust extraction and respiratory protection). And the scaffold-access/ material-handling hazard is that masonry is built from scaffolds (safe scaffold access with fall protection) and is heavy, repetitive work (constantly lifting units and mortar, bending, reaching — a major ergonomic strain, controlled by safe material handling and ergonomic management). The falling material from the scaffold and wall rounds it out. The AHA built on masonry-wall stability and mortar-contact/silica control is the one that protects the masonry crew.
The bottom line
A Unit Masonry AHA names the masonry-wall-stability/collapse, the mortar-caustic-contact/cutting-silica, and the scaffold-access/material-handling hazards with specific controls — bracing masonry walls during construction (an unbraced fresh masonry wall can collapse, especially under wind, a recognized killer), preventing caustic mortar contact and silica control for cutting units, and safe scaffold access with managed material handling. The masonry-wall stability and the mortar-contact/silica control are the defining concerns. The AHA that manages both is the one that protects the crew.
Frequently asked questions
Why is masonry-wall stability the defining hazard?
As a masonry wall is built up, a freshly laid wall is NOT stable until the mortar cures and it is properly braced, and unbraced masonry walls under construction can collapse — most dangerously under wind loads, which can topple a tall, freshly laid, unbraced wall and kill workers on or near it (a recognized and repeated masonry-construction killer). Controls are bracing masonry walls during construction (per the requirements limiting unbraced masonry wall height, a limited access/exclusion zone behind a wall being built or braced), and the wall-stability controls.
What mortar and silica hazards apply?
Masonry is built on mortar, which is cement-based and caustic, and masons work with it constantly, so prolonged skin contact causes cement burns; cutting masonry units generates respirable silica. Controls are preventing skin contact with the caustic mortar (gloves, skin protection), silica control for cutting masonry units (wet cutting/dust extraction, respiratory protection), eye protection, and the contact/silica controls.
What access and handling hazards apply?
Masonry is built from scaffolds (fall hazard) and is heavy, repetitive work (lifting units and mortar, bending, reaching). Controls are safe scaffold access (properly erected masonry scaffolds, fall protection), safe material handling and ergonomics (hoisting to the scaffold, staging, ergonomic management), and the access/handling controls.
What is unit masonry?
Unit masonry is the construction of walls and structures by laying masonry units (brick, concrete block, stone, tile) in mortar — the core masonry-laying activity, building up courses of units bonded with mortar into walls, partitions, and structures. Because an unbraced fresh masonry wall can collapse, mortar is caustic and cutting units generates silica, and the work is at height and heavy, those hazards apply.
Related AHAs and JHAs
- Concrete Unit Masonry AHA — the concrete-block masonry detail
- Clay Unit Masonry AHA — the clay-unit masonry detail
- Common Work Results for Masonry AHA — the masonry work fundamentals
- 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.