NVQ Diploma in Bricklaying (Construction) Decorative, Curved and Specialist Masonry Syllabus

What is a centre (former) and what are its main parts?

A centre is a temporary built-up timber framework supporting an arch during construction. Main parts: ribs (curved profile boards), ties/cross-bearers, struts/laggings (boards across the ribs forming the curved surface the bricks rest on), and folding wedges beneath for striking.

Why are folding wedges placed under a centre?

They allow the centre to be eased and lowered ('struck') gently and evenly after the arch mortar has set, so the arch takes up its load gradually without shock — and they let the centre be removed without damaging the arch.

When may an arch centre be struck (removed)?

Only after the arch mortar has gained sufficient strength to be self-supporting (typically allow the mortar to set/cure — often at least 24 hours or longer in cold conditions). Striking too early can cause the arch to drop or collapse.

How do you set out a semicircular arch?

The radius equals half the span; place the compass/trammel point on the centre of the springing line and strike the semicircle. The rise equals the radius (half the span). Voussoirs are set out radiating from this single centre point with equal taper.

How is a segmental arch set out, and how does its centre differ from a semicircular arch?

A segmental arch is part of a circle whose centre lies below the springing line. The rise is less than half the span, so the radius is larger than for a semicircle and is found by geometry/trammel; voussoirs radiate from that lower centre and the arch springs from inclined skewbacks.

Why must arch joints (between voussoirs) radiate to the centre of curvature?

So each joint is perpendicular ('normal') to the curve. This makes the voussoirs act as true wedges transferring load in compression through the ring to the abutments; non-radial joints create slip planes and weaken the arch.

Why should an arch have an odd number of voussoirs?

An odd number lets a single keystone sit centrally at the crown, giving a symmetrical appearance and locking the two halves of the arch evenly.

How do you set out a radial (curved) wall on the ground?

Establish the centre point of the curve and the radius; use a trammel (rod/line pinned at the centre) or string compass to scribe the inner and outer faces of the wall on the foundation, then dry-bond bricks around the curve to set joint widths before building.

How are bed and cross joints arranged on a curved (radial) wall?

Cross (perpend) joints are set radial — pointing toward the centre of the curve — so they are wider at the convex (outer) face and narrower at the concave (inner) face. Tight curves may require purpose-made/cut radial bricks to keep joints within limits.

What governs whether standard bricks can be used on a curved wall or whether radial bricks are needed?

The radius of curvature relative to brick size. A large radius allows standard bricks with slightly tapered (wedge-shaped) mortar joints; a tight radius would make outer joints too wide or inner joints too thin, so purpose-made radial (voussoir-shaped) bricks are required.

What is a brick-on-edge coping and what is its purpose?

A capping course of bricks laid on their long edge along the top of a wall (e.g. boundary or parapet wall) to finish it and protect the brickwork below from rain penetration by shedding water away from the wall top.

How does brick-on-end differ from brick-on-edge?

Brick-on-end (soldier) units stand vertically on the header face — used for soldier courses, copings and sills. Brick-on-edge units lie on their long edge with the bed face vertical — common for copings and the top course of sills/cappings.

What features make a coping more weatherproof than a capping?

A true coping oversails (projects beyond) both faces of the wall and incorporates a drip/throat groove on the underside of the overhang, plus often a damp-proof course beneath it, so water drips clear of the wall face. A capping sits flush with the wall faces and offers less protection.

Why should a damp-proof course (DPC) be bedded under a brick-on-edge coping?

To stop rainwater that penetrates the porous coping from travelling down into the wall below, preventing saturation, frost damage and staining of the brickwork.

How is a brick-on-edge sill set out to throw water clear of the wall?

The sill bricks are laid on edge with a forward fall (slope/weathering) and project beyond the wall face with a drip groove on the underside, so rain runs off the sill and drips clear instead of running back into the wall below the window.

Define corbelling in brickwork.

Corbelling is building successive courses to project (oversail) progressively beyond the face of the wall below, each course stepping out to form a bracket, ledge or decorative feature.

What is the general rule limiting how far each course may corbel out?

As a guide each course should oversail by no more than about one quarter of a brick (roughly 25–30 mm), and the total projection should not exceed the thickness of the wall (the centre of gravity must stay within the supporting wall) to remain stable without falling forward.

What is a dentil course?

A decorative course in which alternate headers (or bricks) project and recess, creating a regular tooth-like pattern of light and shade along the wall — often used in eaves, cornices and feature bands.

What is a string course (band course)?

A continuous horizontal band running across an elevation, formed by projecting bricks, a different brick type/colour, or special units, used decoratively to break up a wall and often to mark floor levels; a projecting one also helps shed water.

What is diaper work?

A decorative diamond, lozenge or repeating geometric pattern created across a wall face using bricks of contrasting colour (e.g. burnt/vitrified headers) within the bond, common in Tudor and Gothic Revival brickwork.

What does 'polychromatic brickwork' mean?

Brickwork using bricks of two or more colours arranged deliberately to form patterns, bands or motifs in the wall face — popular in Victorian architecture (e.g. red brick with contrasting blue, buff or white bands).

What planning is needed before building a patterned (diaper/polychromatic) panel?

Set out the pattern fully — often dry-bonded or drawn on a setting-out rod/grid — to fix brick positions and colours, ensure the pattern centres on the panel and aligns with bond and perpends, and check the contrasting bricks are sized/sorted before laying.

What is a soldier course and why must it be carefully set out?

A course of bricks stood vertically on end (brick-on-end) with the long face showing, used over openings and as a feature band. It must be plumbed individually and gauged so the perpends are even, because any leaning or irregular joints are very obvious in a vertical course; it usually needs support (lintel/angle) as it has little inherent strength.

What is a feature panel in decorative brickwork?

A defined area of brickwork built with special bonding, projecting/recessed units, contrasting colours or patterns (e.g. basketweave, herringbone, diaper) set within plain surrounding brickwork to create a decorative focal point.

What is a chimney breast and how does it relate to the stack?

The chimney breast is the projecting masonry within the building that contains the fireplace opening and flue. The stack is the part of the chimney that rises above the roof line. The breast carries the flue up through the structure to the stack.

What is the minimum brickwork (thickness) generally required around a flue, and why?

Flues are usually surrounded by at least half-brick (102 mm) thick masonry, with flue liners inside, to contain combustion gases, resist heat, and prevent fire spread and gas leakage into the building. Withes/midfeathers separate adjacent flues.

What is a flue liner and why is it used?

A flue liner (clay/ceramic or pumice/concrete socketed pipe) is built inside the flue to provide a smooth, heat- and acid-resistant, gas-tight passage for combustion products, protecting the surrounding brickwork and improving the draught.

Which way up are socketed flue liners installed, and why?

Liners are built socket (rebate) uppermost so that condensates and tar run down the inside of the joint and stay within the flue, rather than soaking into the surrounding brickwork.

What is a gather in a chimney?

The gather is the tapering section above the fireplace opening (throat) that narrows the wide fireplace recess down to the size of the flue, smoothly funnelling smoke and gases into the flue to maintain an effective draught.

What is a flue offset (bend) and what limits its angle?

An offset is a change of direction in the flue (e.g. to clear an obstruction or position the stack). It should be as gradual as possible — typically not more steeper than about 45° from vertical (some guidance limits to 30°) — so the draught and the ability to sweep the flue are maintained.

What are the main parts of a fireplace opening at the hearth?

The constructional (back) hearth and superimposed (front) hearth of non-combustible material, the fireback, the throat and gather above, the lintel/arch over the opening, and the surrounding jambs of the chimney breast.

Why must a hearth be built of non-combustible material and project beyond the opening?

To prevent heat and falling embers from igniting the floor; building regulations require a solid non-combustible hearth of specified thickness that extends in front of and to the sides of the opening to protect surrounding combustible flooring/structure.

What is chimney weathering and how is flashing used at the roof?

Weathering is shaping the masonry (and flaunching) to shed water. At the roof intersection, flashings (front apron, stepped side flashings and a back gutter/soakers, usually lead) are dressed between the stack and the roof covering to make the junction watertight and stop rain entering the building.

What is flaunching and what is a chimney capping/pot arrangement?

Flaunching is the sloping (weathered) mortar bed on top of the stack that beds the chimney pots and sheds water off the stack top. The capping/pot finishes the flue: pots or terminals raise the outlet and improve draught, while the weathered flaunching and any capping prevent rain entering around them.