Recommendations for Good Brick Masonry Construction Practices
Madeh Izat Hamakareem
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Several recommendations for good site brick masonry construction includes practices for accuracy and tolerances, appearance, durability, structural performance, weatherproofing, thermal performance and accommodation of movements.
Recommendations for Good Brick Masonry Construction Practices
1. Accuracy and Tolerances
It is highly recommended to set accuracy requirements for the finished brickwork with regard to structural frames, designated openings, adjacent elements, and any other visual requirements.
It is required to establish all works properly for lines and levels before the beginning of the brickwork. Great cautions shall be practiced while shelf angles or other brickwork supports which are part or attached to structural frame, are installed.
It is possible to lay two dry courses of brick for the locations that high quality brickwork are needed. This will decrease brick cuttings and the bond could be compared with proposed openings further up the wall.
Clay bricks are available with different in size, that is why great skills are needed for the placement of these bricks. Due to clay brick size variations, all perps cannot be plumb and 10mm between all bed joints cannot be maintained.
So, if more accurate positioning of perps and bed joint width are needed for aesthetical reasons, it is required to use accurate concrete bricks rather than clay bricks.
It is possible to construct aesthetically pleasing brickworks if perp positioning is planned in advance. For example, plumbing every fifth perpend would offer visually appealing appearances. This process shall be repeated for the entire height of the brickwork.
It is recommended to clean the brickwork as the work is preceded and the work shall be protected from rain, frost, and adjacent activities that may affect the brickwork physically and aesthetically.
So, boards and other equipment shall be moved away from brickwork at end of the day. This will also prevent splash of rain on the brickwork.
Acid cleaning may be required if the brickwork is not properly protected and conducted with good standard. Acid cleaning will influenced the brickwork appearances, so it must be carried out carefully and clean the area with water quickly.
It is advised to select bricks for its durability in accordance with the degree of exposure. Brick producer recommend mortar strength related to the strength of the brick. If the strength of mortar is lower than that of bricks, then any movements would cause cracks initiation in the mortar.
So, it is necessary to cure the mortar properly so as to achieve the required strength and it should be protected from frost action till it reaches designated strength. This can be achieved by incorporating insulating materials underneath water tightness protection.
4. Structural Performance
Structural performance of wall is based on all wall supports and restraints for example footing, lintel, shelf angles, wind posts, special anchors or hangers, and cavity wall ties. All these are needed to be installed according to the manufacturer’s recommendation and applicable code specifications.
The rate of laying bricks shall not surpass 1.5m per day. The mortar shall be of required strength and need to be consistent throughout the work.
It is recommended to practice solid cross joints rather than employing two smaller dabs of mortar or tipping and tailing brickworks. This is because the latter would weaken the structural performance of the brickwork even though it saves materials and cut construction time.
With regard to bearing of shelf angles and other similar objects, it should not be less than two third of the brickwork width. Another important consideration is the ties used in the cavity wall. It frequently installed poorly or missed due to its small size.
Nonetheless, it plays significant role since it make two adjacent wall work together. So, if cavity wall ties are not installed or misplaced, the walls will work separately which compromise the performance of the wall.
The weather proofing of external cavity wall is dependent on the principle of cavity that acts as barrier.
Mortar protrusions and droppings will decline effectiveness of cavity. So it is necessary to clean the cavity during brick masonry construction.
It is required to use partial cavity fill or fully filled cavity so as to achieve proper thermal insulation. Construction of these types of masonry wall needs substantial cautions.
So, it might be necessary to consider the recommendation of manufacturer on how to construction partially or fully filled cavity walls.
Finally, it is required to make sure that all bed joints and cross joints are fully filled because such joint type play significant role in the weather-tightness of the masonry wall.
6. Thermal Performance
It is required to prevent any space in the insulating layers and they should be as dry as possible before and after placement. If large degree of thermal insulation is required, then fully filled cavity walls need to be constructed.
In order to achieve required thermal performance, it is required to take manufacturer instructions on how their materials shall be installed to obtain designated thermal performance.
Finally, the prevention of capillary movement of water through joints of fully filled cavity wall is the greatest challenge.
7. Movement Accommodation
It is required to provide movement joints at proper spacing to make rooms for anticipated movement for example clay brick expand 1mm per 1m over its service life.
Moreover, compressible materials should be used for joints and good workmanship plays significant role. Finally, the details of joints shall be discussed with the mason prior to the beginning of the work.
8. Holes and Chases
Hoes generate considerable problems for brickwork subcontractor. So, it is required to produce drawing of holes with the locations of services that pass through the holes.
These drawings will ease the work for brickwork subcontractor in addition to set up those variations which are instructed to late to be incorporated.
9. Lead Flashings
If lead flashing is needed to be installed underneath damp proof course, then it is advised to introduce a clean rebate in the brickwork beneath or wide bed joint incorporating timber lath to line up with front face of brick work. This will help proper installation of lead flashing.