BrickLaying

Images - Wix

Typically, a brick wall is a vertical element of construction that is made of bricks and mortar and is used to form the external walls of buildings, parapets, internal partitions, freestanding walls, retaining walls and so on. (Designing Buildings, 2021)

Bricklaying Terms

Arris - Any straight edge of a brick

Header - The end face of a brick (Fig 1)

Stretcher - The longer face of the brick (Fig 1)

Fig 1 Brick Positions, Image - Wikipedia

Bat - Part of a brick eg. half bat equals 1/2 a brick, quarter bat equals 1/4 brick

Bed joint - A horizontal joint in brickwork

Cross Joint - A vertical mortar joint between bricks

Plumb -The control of brickwork vertically

Course - A row of bricks laid in mortar

Racking back - A stepped diagonal line to be joined with later work

Quoin - The external corner of a wall (Fig 2)

Fig 2 Quoin, Image - Pinterest

Soldier - A brick laid vertically on end (Fig 3)

Fig 3 - Soldier Bricks, Image - builderbill-diy-help.com

Solid Concrete Block - Widely used in construction (Fig 4)

Hollow Block - Concrete block with voids (Fig 4)

Fig 4 - Solid & Hollow Concrete Blocks, Image - TJ O'Mahony.ie

Concrete - A mixture of sand, gravel, cement, and water that sets and hardens

Bond - The arrangement of bricks in a wall (Fig 5)

Fig 5 - Bond Patterns, Image - playbricks.com.au

Pier - Local thickening of a wall to improve its stiffness

Cavity Wall - A wall with two leaves (Fig. 6)

Fig. 6 - Cavity Walls, Image - cwinsulations.ie

Weephole - A hole through brickwork through which water can drain

Sill - The lower horizontal edge of an opening

Brick Sizes

Actual Size – Coordinating Size – Work Size

Work size is the size of a brick or block specified for its manufacture. Coordinating size is the size of space allocated to a brick or block including an allowance for mortar joints. Actual size of a brick or block is measured on site as bricks can vary in size. The standard size of a brick is 215mm x 65mm x 102.5mm. Brickwork must tie in with sizes of other components of the building project, most importantly height. This is referred to as gauge. (Fig. 7) Standard gauge for brickwork is 75mm per course or 4 courses to 300mm.

Fig 7 - Image wonkeedonkeetools.co.uk

If bricks are slightly more, or less than 75 mm tall, mortar joint depths will have to be decreased or increased accordingly.

Block Sizes

Concrete blocks come in different sizes and colours. The 100mm (100mm x 215mm x 440mm) solid concrete block is most widely used in construction, can be laid on its edge to give a 100mm thick wall or on the flat to give a 215mm thick wall. When calculating for brickwork always factor in a 10mm mortar joint eg. in a 100mm thick wall the block should be calculated as 450mm long by 225mm high .

To calculate the number of blocks per m2:

Find the area of 1 block - 0.45m x 0.225m = 0 .101m2

Then 1 ÷ 0.101 = 9.9 i.e. 1m2 = 9.9 blocks (rounded up to 10).

Cavity blocks are lighter than solid blocks, can only be laid on their edge and only used above ground level. They have the same dimensions as solid cavity blocks.

Filler blocks (stock bricks) are used for making up levels in block walls eg. around window or door openings. Their dimensions are 215mm x 65mm x 100mm.

215mm hollow blocks are used to build above ground level for example in houses, sheds, and boundary walls. There are 9.88 (rounded to 10)/m2. Standard size is 440mm long x 215mm high x by 215mm wide. Because cavity blocks are difficult to cut there are purposely made half-hollows or footballs which measure 215mm x 215mm x 215mm. As fairfaced blocks will not be rendered or plastered the jointing which will be visible must be of an excellent standard.

How to Set Out the First Course of a Concrete Block Wall:

**Always remember- plumb, level, in range and gauge**

1. Check foundation is level.

2. Set up a line from 2 deadmen (upright blocks).

3. Dry bond the first course of blocks leaving 10mm space between each one.

4. Starting at one end, spread a bed of mortar 15-18mm thick on the foundation, laying the first block on this bed joint. As there will be a pier at each end the block has to be laid flat with a second block on top to achieve the height of 225mm. Check level (lengthwise and widthwise), plumb and height. Fill the trowel with mortar and lay second brick on top of first one, tamp down, check levels, gauge (225mm) and plumb on both faces of the bricks.

5. This process is repeated at the opposite end. When the blocks are set up and checked for range the other blocks can be laid using the line, continually checking levels, plumb and gauge.

6. Using a trowel, a cross joint of mortar is placed against the first block. The joint should be thick enough (12-15 mm) to allow the mortar squeeze out when the next block is laid against it. Continue until all blocks of the first course are in place, laying to the line using the block beside it as a guide, checking for plumb before moving on to the next block. The perps can be jointed using a jointing bar to achieve a neat finish to the mortar.

Image - Concretebroker.com

Building a Lead for 2nd and Subsequent Courses

A lead can now be built at each end of the wall. When a 1/2 block is required an allowance of 10mm for the joint needs to be considered.

i.e.. 2 x ½ blocks plus 10mm joint = 440mm.

1. A block is cut at 215m using a lump hammer and bolster. The second half is cleaned off to achieve 215mm.

2. A bed joint is spread long enough for a block and 1/2.

3. Lay the half block first, put on a cross joint then lay the full block checking levels, gauge and plumb.

4. A second block is laid directly behind the joined half block and ½ of the full block checking levels, plumb, gauge, and range (diagonally across the two courses).

5. The lead for the third course is then laid as per the 1st, with two blocks laid on top of one another on the flat.

6. The opposite end of the wall is completed in the same way and the blocks in between run in against a line using the blocks below as a guide.

7. The line is then raised and run in for the third course. When the third course is complete a lead can be built at either end of for course 4, the last course run in using the line.

Lintels, Sills & Mortar

Concrete lintels (Fig 8) are used to span over openings in blockwork. They should be bedded in mortar at supports and propped at 1.2m intervals until the masonry has dried. Lintels should have minimum bearing on each side of 150mm for spans up to 1.5m, 200mm for spans 1.5-3m.

Figure 8, Image - Pinterest

Window sills (Fig 9) should be enveloped in DPC of suitable width (450mm) and extend 100mm longer each side of the opening. e.g., an 1800mm window should have a sill 2000mm wide.

Fig. 9, Image - manorstone.ie

Calculating volumes of mortar required: One tonne of building sand with cement and lime will lay 250 solid blocks on edge or 125 blocks flat. 1m3 of trowel-ready mortar will lay 1000 blocks on edge, 500 on flat.

Retaining Walls

Image - istockphoto.com

Retaining walls are built to retain masses of water (dams) or earth (revetment walls). They are constructed from brick , stone, or reinforced concrete. (Fig 10) Retaining walls must resist tendency to slide or fail when pressure is applied to them.

Fig. 10 - Image, Allanblock.co.uk

They must have sufficient weight to counter the pressure and weight of the materials it holds, foundations wide enough to provide friction against the ground and wide enough to resist shearing. Many retaining walls are rectangular in shape and are built using half brick offsets or battered face. The tapered design accounts for lower pressures at the top of the wall. If pressure is expected to build up from water large granular material and pipes can help drain from the earth behind the wall. Retaining walls with battering faces are constructed using plumb rules or adjustable vertical spirit tubes.

Curved Walls

Image - building.co.uk

The three most common ways of constructing curved brickwork are (a) using alignment with templates and leader boards, (b) plumbing points or (c) trammel.

Setting out Curved Walls

1. The centre of the circle which the curve is part of is established and marked out using a trammel or string line .

2. The curve of the wall must be set out in the foundation.

3. 1st Course - must be dry bonded first to ensure the cross joints are equal, and level so gauges can be taken from it over the entire height of the wall, helping maintain the levels during building.

4. Carefully bed the first course of bricks to the line of the radius marked in the screed, using the trammel to check the alignment.

Building Curved Walls

(a) Alignment with Templates & Leader Bricks

Leader bricks are built to serve as a gauge for the next layers of bricks. They should be leveled and plumbed on all sides against the first course and evenly spaced out all through the full length of the wall. The leader bricks are spaced apart the same length as the template which is then used to range the rest of the bricks. (Fig 11)

Fig 11, Image - markedbyteachers.com

In this scenario (Fig 11) the template is on the outside of the wall - both arrises of straight bricks must touch the template.

(b) Alignment using Plumbing Points

The middle of each brick in the first course has a plumbing point. These points are followed through the full height of the wall to keep the wall perfectly curved and plumb. The plumbing points are the only points where the courses should be checked for plumb. Perpends and gauge should be continuously checked plus levels as each brick is laid. (Fig 12) This is the most accurate way of building curved walls.

Fig. 12, Image - markedbyteachers.com

(c) Alignment using Trammel

The steel rod of the trammel is secured at the striking point and held at the height of the finished wall, plumbed and rigid. A thick rubber band is placed at the bottom of the trammel to keep it in place and level. (Fig. 13) Gauge and perps will be checked continually as the work progresses.

Fig. 13, Image - markedbyteachers.com

Bonding of Curved Walls

Bonds most suited are Header and Flemish bonds. (Fig. 14)

Fig. 14 - Image - building.co.uk

Curved walls can be built using straight bricks utilising wedge-shaped mortar cross joints. Curved walls are stronger than straight walls so can be built less thickly. The curved wall should be dry bonded first before beginning building which will help determine the most suitable bond and how much cutting will be required. For best results radial bricks can be used. (Fig 15) Using radial bricks allows the cross joints to have parallel sides rather than wedge shaped, giving best results but is the most expensive method.

Fig 15, Image - waterdriller.co.uk

Circular Ramps

Image - Pinterest

Circular ramps are used on boundary walls to form decorative features. A convex ramp curves outwards whereas a concave ramp carves inwards. A convex ramp can be set out when the centre of the curve (striking point) and radius are known. The radius of the curve is marked on a timber batten (trammel) and attached to the striking point using a nail.

How to Build a Convex Ramp (Fig 16)

Fig. 16, Image - Pinterest

1. Most importantly brickwork must be accurate (plumb, level, gauge, range, and perpends).

2. The trammel is secured at the striking point using a nail to allow rotation.

3. A pencil is then held at the opposite end of the trammel and the curve is marked on the bricks by rotating the trammel.

4. Once the bricks have been marked out for cutting, they should be numbered, removed from the brickwork, and measurements recorded in case the first cut is not accurately done.

5. Build the cut bricks back into the wall with a capping constructed from bricks on edge.

6. The cross joints in the capping will be V-shaped to accommodate the curve.

7. If the bed joint between the capping and cut bricks is kept at 10mm the curve on the top of the capping should be parallel to the curve set out with the trammel and cut bricks.

8. To measure the number of capping bricks required a measuring tape is bent around the curve.

Example:

(a) Length of curve = 1400mm

(b) Divide 1400 by 75mm (brick + joint) = 18.67 bricks, rounded up to 19 bricks

(c) Divide 1400 by 19 = 74mm - The spacing for the bricks on edge should be 74mm at the bottom

(d) V-shaped joints should measure between 6-10mm at the bottom. The joint in this case will be 9mm which is acceptable.

(e) However, an allowance must be made for an extra joint. 19 bricks = 20 joints

When measuring out the 9mm spacings for the capping joints randomly mark 9 of them at 8mm which will create 1 x 9mm for the extra joint.

How to Build a Concave Ramp - (Fig 17)

Fig. 17 - Image Pinterest

1. The ramp is built, and the trammel fixed at the correct distance for cutting the brickwork for the brick on edge capping.

2. After cutting the bricks the trammel is repositioned to allow for the brick on edge capping and laid using the trammel as a guide.

References:

Designing Buildings. 2021 Available at: https://www.designingbuildings.co.uk/wiki/Brick_wall [Accessed 10.04.2021]