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Building With Clay Brick

Mortar: what materials do I need?
Cements for use in mortar should be common cements complying with SABS EN 197-1 and masonry cements complying with SABS ENC 413-1. CEM 1 32,5 (ordinary portland cement) and CEM 11/A (S, V or W) 32,5 (portland cement 15) may be used in mortar. It is not advisable to use CEM 111/A 32,5 (PBFC). Unless the mortar sands are good quality, mortar with common cement lacks plasticity, may bleed and will be harsh to work with. This deficiency in properties may be overcome by using masonry cement. The use of lime in mortar mixes is beneficial but is difficult to obtain. Masonry cements are readily available.

Sand for mortar should comply with SABS 1090 and be well graded from 5mm downwards. Sand should be evenly graded and should not contain excessive dust or other fine material. The use of fine sands of more or less uniform particle size, though contributing to workability, frequently leads to excessive shrinkage and cracking of the joints. Sands containing high percentages of clay tend to give a conveniently plastic mix, but also lead to undue shrinkage.
  • Crusher sand, because of the shape of the particles (broken edges) yields a rather harsh concrete, but it is fairly consistent and contains no clay.
  • River sand is generally clean and free from clay, the rounded particles pack together easily for good workability Pit sand contains excessive proportions of clay, but may be well graded otherwise. This is therefore not fit for concrete work.
  • Beach or sea sand must be washed. Unwashed beach sand must not be used for mortars as its high cloride content will corrode steel reinforcement and cause excessive efflorescence.
  • Dune sand is generally clean but poorly graded.
  • Mine dump sand is generally unsuitable because it is too fine and may be contaminated with harmful chemicals.
The addition of lime to mortars is a highly desirable and recommended practice and building limes complying with SABS 523 are available from builders merchants. Lime imparts the properties of plasticity and water retention to mortar. The latter property is important as it prevents mortar drying out, resulting in the incomplete hydration of the common cement.
Lime used in mortar is hydrated lime (commercial bedding lime) and not quicklime or agricultural lime. Lime give the best results when used with coarse sands. Lime with clayey sands can make the mortar over-cohesive and difficult to use. Lime should not be used with masonry cement.
Mortar: what are my mixing quantities?
The amount of water added to a mix must be enough to make the mix workable and plastic Use cement that has the SABS mark (SABS ENV 197-1). Masonry cement that complies with SABS ENV 413-1; strength class 12.5 or higher may be used for mortar and plaster.
A builder's wheelbarrow has a capacity of 65 litres
MORTAR:
  • For laying bricks and blocks in normal applications (SABS Class II)
  • To lay 1000 bricks = 3 bags cement + 0.6 cu. m. sand
  • 1 Bag of cement to 3 wheelbarrows of building sand
PLASTER:
  • For exterior and interior work
  • To lay 100sq.m. (15mm thick) = 10 bags cement + 2 cu. m. sand
  • 1 Bag of cement to 3 wheelbarrows of plaster sand
Measure with a container such as a bucket, drum or tin. MORTAR:
  • 1 unit of mortar to 5 units of mortar sand.
PLASTER:
  • 1 unit of mortar to 5 units of plaster sand and stone.
What are the basics of laying bricks?
  • Plan site layout e.g. position of building, material stores, access etc.
  • Store and protect all materials to minimise saturation and contamination.
  • Control the wetting of bricks in hot, windy weather.
  • Do not lay surface saturated bricks.
  • Set out at ground level to locate all openings before commencing bricklaying.
  • Lay out dry and minimise broken bonds.
  • Prepare and take care of gauge rods - they are important quality control equipment.
  • Work all levels from one datum.
The best treatment is to prevent it from getting dirty in the first place - so protect the wall as work progresses from mortar droppings. After the first course of bricks has been laid - protect the base of the wall by laying sand, straw, sawdust or plastic sheeting along the ground. This minimises mud splashes and damage from mortar droppings.
As clay brickwork should be kept dry as possible during construction, cover the walls at the end of each day's work and during rain in order to keep brickwork free from mortar stains.
At the end of each working day clean the toe boards closest to the wall and turn the boards back to prevent rainfall from splashing mortar and dirt onto the brickwork.
  • Mix small batches of mortar to suit building rate and 20 minute initial set timing.
  • Bed all DPC's on fresh mortar
  • Blend face bricks from a number of packs to minimise colour bonding.
  • Plumb, level and square brickwork
  • Fill all mortar joints solidly to minimise water penetration.
  • Clean mortar dropping from cavities regularly
  • Pay attention to DPC details Incline brick ties downwards to the outer leaf.
What bonds or jointing should I use?
Bonding is required to strengthen and stabilise a brick wall and enable it to carry vertical and horizontal loads. There are basically three different bonds that are used in modern building construction.
Stretcher bond (alternate layers of stretchers)
English bond (alternate layers of stretcher and header courses)
Flemish bond (alternate stretchers and headers in the same course)
English Cross or Dutch Bond. English cross or Dutch bond is a variation of English bond which differs only in that vertical joints between the stretchers in alternate courses do not align vertically. These joints center on the stretchers themselves in the courses above and below.
There are two methods used in starting the corners in Flemish and English bonds. Figure 3 shows the so-called "Dutch corner" in which a three-quarter brick closure is used, and the English corner in which a 2-in. or quarter brick closure, called a "queen closure", is used. The 2-in. closure should always be placed 4 in. in from the corner, never at the corner.
Should you wet clay bricks before using them?
Well-made clay bricks should never require wetting before laying except (rarely) under extremely hot and windy conditions.
Clay bricks purchased from non-accredited sources could have unacceptably high porosity and water absorption rates and might need to be soaked on site with water before being used. This slows down the rate of water from the mortar being absorbed by the brick and hence enable a better and stronger bond between the brick and the mortar.
How do I deal with Foundations?
Foundation trenches or excavations must be dug out so that the foundation will rest on hard ground with the trench width and depth that conforms to the drawings and dimensions of the local authority (or the National Home Builders Registration Council (NHBRC)
The trench sides must be straight and plumb and the bottom of the trench level, except in exceptional circumstances.
To ensure that the foundation is level and of uniform thickness, level pegs are to be placed in the trenches to indicate the concrete thickness. These levels are very  important as they represent the start of the brickwork.
When the ground slopes, the trench bottoms must be stepped so that the foundation itself does not slope but is stepped. The step should be equal to one or more courses of brickwork.
How do I deal with surface beds?
Generally a minimum of 75mm thick 15MPa concrete cast on a layer of compacted fill (or hard core) is required. In wet climates or low lying situations surface bed should be cast on a polyethylene sheet at least 0,25mm thick.
Top level must be to at least 150mm, or two brick courses about external ground level.
How is brickforce used in unreinforced walling?
Brickforce is a British product consisting of two main parallel wires joined by in-line welded cross wires. Main wires are manufactured to a flattened profile to simplify location into the mortar joint without steel build-up problems at lap positions corners/junctions or when used in conjunction with wall ties.
Masonry has excellent compessive qualities and the majority of buildings constructed using this material last for many years with little maintenance. However, masonry has no significant tensile strength and movement caused by substrata changes, moisture or thermal effects can cause cracking.
The use of masonry reinforcement is a very simple and cost-effective way of greatly enhancing the strength and durability of masonry construction by providing both structural and crack control benefits.
It ties the wall together thus providing stability. Over unsupported openings like windows ,doors etc., Brickforce strengthens the wall. If you are building on unstable ground (i.e. there is movement in the ground) it is always good practice to use brick force thus ensuring a very stable wall.
Various types of alternative masonry reinforcement products are also available including mesh and wire.
What brick do I use to build a fire wall?
Question continues: "The walls are 3m high by 4.5m wide by 0.2m thick, and supported at each end of the 4.5m I believe this will have a fire rating of 240 minutes? How do I support the wall for strength against wind? Are steel wire wall ties sufficient? "
ANSWER
I suggest a double skin masonry wall in standard imperial clay brick, with each leaf 106 mm in thickness. This will yield an overall wall thickness (unplastered) of 212 mm which will have a nominal fire rating of 240 minutes.
I would recommend supporting each 4 meter length of wall with a 340 x340mm brick pillar at each end, as well as using wire ties as suggested.
Chris Dickinson Corobrik
What is the recommended gap for clay pavers...
Question Continued: The recommended gap between bricks in a pavement is 2 – 6 mm which is a wide range. What is ideal? Most pavers seem to be laid with the ridges touching a neighbouring block creating points of contact. Should the gap be between the ridges or the paver faces?
Will expansion set up compressive stresses if the gap is insufficient?
Answer The gaps on the pavers are 2mm to 6mm, which are to account for both PA and PB pavers so that lines may be maintained. (see the tolerances in the spec's on both types of pavers)
The "nibs" technically are only to assist with laying and are not for any structural reason. Most nibs are offset so as not to end up contacting each other, but strictly speaking, the jointing material is designed to diffuse the lateral and vertical forces by transferring them through to the bedding sand and sub-bases layers.
It is highly recommended that the grade of jointing material is different to the bedding sand, to expand in the joints and create the lockup. It must also be vibrated so that it fills the joint to the bottom and in so doing allow the forces to be transferred through. Again, one of the more important issues in the design is the edge restraint which holds the whole system together, and patterns relevant to the usage are also critical.
Please download the "Movement of Brickwork" technical paper.
What are the duties of a Health & Safety Officer?
Attached are the answers from RFI 041 on the subject of the Duties of an HSE Officer in the Construction industry.
Dave Bass BuildSafe South Africa
Recommended practice for cavity wall construction
The insulation of external masonry walling in the RSA buildings is not mandatory in terms of the National Building Regulations. This Technical Note details the requirements for walling in terms of Regulation XA and SANS10400XA.
Thermal insulation or thermal resistance is achieved by means of three different mechanisms of attenuation of heat transfer: these define the three types of thermal insulation: resistive, reflective and capacitive, two of which are commonly present in insulated masonry wall assemblies. The third, reflective insulation, is often used in low mass (timber or light steel frame) walling constructions
Do I need Fire (Refactory) bricks for a fireplace?
Firebricks (or refractory bricks – correct term) are a frequent enquiry. In a domestic fireplace or braai they are really a total over spec. Refractory Bricks are normally rated from around 1600'C upwards. They are expensive and not easily available.
A braai will never reach these kinds of heat and all facebricks are fired to around 1000 – 1250'C. The heat in the fireplace must get higher than this to have any effect on the brick. Generally your mortar joint will fail before the brick. What I always suggest to people is the following.
Build the outer skin of the sides of the braai/fireplace with a standard mortar mix (1 bag cement : 3 Barrows Sand) with brickforce and cavity ties. Build the inner skin with a well burnt clay face brick using a weaker mix (1 bag : 6 Barrows Sand) – this allows more joint movement and reduces cracking from heating.
The base is normally the area that gets the most heat as the fire is resting on this. It is also normally made from concrete (cast or lintels) which cannot withstand these high temperatures. Here a clay paver or solid clay brick can be laid on a sand bed. Do not cement bed or grout – it must have some movement to allow for heating and cooling expansion / contraction. The bricks / pavers at the opening to the braai can be grouted in to form an edge restraint. The fire generally is never built right at the opening so they don't get as much heat. Grouting these prevents the pavers behind from falling out / working loose. It acts like a kerbing.

Mark Hunter-Smith Algoa Brick
How do I build a Cavity Wall?
A Cavity wall is superior both from a water penetration/dampness and an energy efficiency perspective.

The bonding pattern/layout of bricks around windows Please see attachment 1 for various options available.

The installation of lintels - 280 mm cavity wall) As per the drawing on attachment 2: You would need to use two lintels, one 106mm and the other 164mm as illustrated.

Installation and waterproofing of window sills Attachment 2 shows for various options

Closing, sealing and rain-proofing the tops of parapet walls. Two methods are shown on attachment 1 but I would suggest you discuss this with a waterproofing or roof specialist before implementing.

Recommended : wall-tie spacing

We recommend at least 3 wall ties per sqm of walling. I'm not sure which region of SA you reside in but in Cape Town these are readily available at nearly every building material supplier.
I need to stress that the drawings attached are only typical details and each projects detail need to designed around that specific applications. Therefore, I would strongly recommend that it be discussed with a qualified architect or engineer to see if they are best suited for your particular application.
All the best to you with this project.

The attachment are from "Building Construction and Graphic Standards" written by Andre Grobbelaar. For a more detailed referencing herewith the books details:
ISBN-13: 9780620077873 (ISBN-10: 0620077875)
Format: Paperback
Publisher: Anglo-Rand Publications
Publication Date: 01 Dec 2006
Country of publication: South Africa

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