Last reviewed 16 Sept 2026 · 10 min read
Masonry
Masonry is construction with individual units (stones, bricks, blocks) laid and bound together with mortar. Stone masonry is used for foundations, walls, retaining walls, piers, abutments, dams and architectural facings where good stone is locally available.
Technical terms
| Term | Meaning |
|---|---|
| Course | A horizontal layer of stones or bricks |
| Bed | The surface of a stone perpendicular to the line of pressure (its top/bottom in a wall); bed joint — horizontal mortar joint |
| Joint (cross/vertical joint, perpend) | Mortar joint perpendicular to the bed joints |
| Header | A stone (or brick) laid with its length across the wall (perpendicular to the face) |
| Stretcher | A stone laid with its length along the face of the wall |
| Through stone (bond stone) | A stone extending through the full thickness of the wall — ties both faces together |
| Quoins | Stones forming the external corners of walls, usually larger and dressed |
| Corbel | A stone projecting from the wall face to support a beam, cornice or other load |
| Cornice | A projecting ornamental course at the top of a wall (also sheds rainwater) |
| Coping | Covering course on the top of a wall/parapet to protect it from rain; weathered (sloped) and throated |
| String course | Horizontal course projecting from the wall face along its length (at floor or sill level) — appearance and weather protection |
| Plinth course | The top course of the plinth |
| Jambs | Vertical sides of a door or window opening |
| Reveal | The exposed part of the jamb between the frame and the wall face |
| Sill | Horizontal member at the bottom of a window opening (weathered to shed water) |
| Lintel | Horizontal member spanning over an opening |
| Hearting | The interior filling of a wall between the face and back stones |
| Spalls (pinnings) | Small chips of stone used to fill interstices in rubble masonry |
| Weathering | Sloping top surface of projecting courses to shed rainwater |
| Throating | A groove on the underside of a projecting course or sill so that water drips off and does not run back to the wall |
| Blocking course | Course placed above a cornice to weigh it down |
| Parapet | Low wall at the edge of a roof, terrace or bridge |
| Template | A stone/concrete block placed under a beam to distribute load on the wall |
| Arris | The sharp edge where two surfaces of a stone meet |
Classification of stone masonry
1. Rubble masonry
Stones of irregular sizes and shapes (as obtained from the quarry or roughly dressed) laid in mortar. Economical but lower strength than ashlar.
| Type | Description | Use |
|---|---|---|
| Uncoursed random rubble | Stones of irregular shape and size laid without regular courses; interstices filled with spalls and mortar; larger stones at corners and jambs; through stones at intervals | Walls of low-height buildings, compound walls, godowns, foundations |
| Coursed random rubble | Stones of irregular shapes brought to level courses at intervals (e.g. every 30–45 cm) | Residential buildings, public works — better than uncoursed |
| Uncoursed squared rubble | Stones roughly squared (hammer dressed) laid without courses | Ordinary buildings |
| Coursed squared rubble | Squared stones in courses of varying height | Better class walls |
| Regular coursed rubble | Squared stones with uniform course heights | Public buildings, residential buildings, piers and abutments of ordinary bridges |
| Polygonal rubble | Stones hammer dressed to polygonal (irregular polygon) faces fitting together | Decorative walls |
| Flint rubble | Flints (nodules of silica) as facing, with lacing courses of brick or stone | Regions where flint is available |
| Dry rubble masonry | Rubble laid without mortar, carefully packed with spalls | Retaining walls on hill roads, pitching, compound walls, revetments (allows drainage) |
2. Ashlar masonry
Stones finely dressed to regular shapes and sizes, laid in courses with fine, thin joints (often about 3–6 mm). Strong, attractive, but costly.
| Type | Face finish |
|---|---|
| Ashlar fine | Every stone finely dressed on all sides; very thin joints — superior facing, monuments, important buildings |
| Ashlar rough tooled | Bed and side joints finely dressed; exposed face rough tooled (with a margin chisel-drafted) |
| Ashlar rock (quarry) faced | Exposed face left rough as from the quarry, with chisel-drafted margins — rustic appearance, massive look |
| Ashlar chamfered | Edges of the exposed face chamfered (bevelled) to form grooves at joints — used for plinths, quoins |
| Ashlar facing | Ashlar stones used as facing with rubble or brick backing |
| Block-in-course | Intermediate between rubble and ashlar — stones squared and dressed, courses of uniform height (often 20–30 cm), joints thicker than in ashlar — heavy works (bridges, docks, retaining walls) |
3. Composite masonry
A combination of different masonry types or materials — e.g. stone facing with brick backing, stone and concrete — for economy and appearance while using cheaper backing.
General principles of construction
- Use hard, durable, well-seasoned stones free from defects; wet stones before laying to avoid absorbing water from mortar.
- Lay stones on their natural bed (bed perpendicular to the pressure); in arches the bed is radial; in cornices vertical.
- Provide through (bond) stones at regular intervals (commonly about 1.5–2 m apart in each course and at every course or alternate courses in height) or headers overlapping from both faces where full-length stones are not available.
- Break (stagger) vertical joints in successive courses — avoid continuous vertical joints.
- Face stones should tail well into the wall (length into the wall at least equal to height); hearting solidly filled with stones, spalls and mortar — no hollow spaces.
- Use the largest stones in the lower courses, at corners (quoins) and jambs.
- Use mortar of suitable proportion (commonly cement mortar 1 : 6 for rubble work); joints fully filled.
- Raise walls uniformly throughout their length — limit the height raised in a day; stagger (rack back) junctions for later work.
- Keep walls plumb and courses level; check with plumb bob and spirit level.
- Cure masonry by keeping it wet (commonly at least 7 days for cement mortar).
- Protect fresh work from rain, frost and hot sun.
- Provide weathering and throating on projecting courses; coping on parapets.