Unit 2046 - Brickwork Level 2 CAA Diploma ... - Pearson Schools

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Unit 2046 How to carry out thin joint masonry and masonry cladding 168 Level 2 NVQ/SVQ Diploma Brickwork 3rd edition Remember Forms of construction where the thin joint system can be used The standard block size is 440 mm x 215 mm Safety tip Always remember the basics of kinetic lifting techniques when handling blocks, particularly the larger size blocks available with the thin joint system Remember It is essential that the bed course is level and free from imperfections prior to laying the first bed of the thin joint mortar Remember You must always ensure that the course that is to receive a bed of thin joint mortar is free from dust as this can adversely affect the adhesion of the mortar Key term Superstructure – work above the DPC Figure 5.17 A bed course of blocks laid with traditional mortar bed and with thin joint mortar vertical joints The structure and composition of Aircrete blocks make them a very versatile material. When they are used in conjunction with the thin joint mortars that are now available, the thin joint system becomes suitable for most aspects of construction normally associated with the more traditional types of materials. The thin joint system can be used for any of the following: foundations partition walling external solid walling cavity walling separating or party walls. As the thin joint system has high resistance to both water penetration and frost, few problems are encountered when it is used for external solid walling. However, it is recommended that the external face of the blockwork is finished with either cladding or a traditional rendered finish, particularly where the wall is constantly exposed to inclement weather, such as rain and frost. The thin joint system also has a high resistance to fire and good sound insulation qualities, making it highly suitable for the construction of partition walling and separating walls. The strength and sulphate resistant properties of the system, also make it suitable for foundation walls in most types of soil and ground conditions. Methods of construction using the thin joint system If constructing a cavity wall structure, it is important to ensure that the substructure walls are built up to the damp proof course (DPC) prior to laying the inner thin joint blockwork. This enables any required openings to be set out accurately before work starts on the superstructure. 2–3 2–3 mm mm thin joint thin mortar joint – mortar – vertical joints joints in order in to order to maintain bonding accuracy for maintain the next course bonding of blocks accuracy for the next course of blocks 10 mm bed joint laid with traditional mortar to enable any inaccuracies 10 mm bed joint in the la concrete to be traditional mortar taken inaccuracies out and in to theproduce a level bed taken for the out and thin to joint p system bed for the thin jo
Unit 2046 How to carry out thin joint masonry and masonry cladding In most cases the first course or ‘bed course’ in the thin joint system should be laid using the normal sand/cement mortar. This will take out any inaccuracies that are present within the floor slab or foundation masonry. In order to maintain accuracy in the courses above the bed course, thin joint mortar may be used for the perps (vertical joints) of the bed course. Once the bed course is sufficiently stable, work with the thin joint system can commence. Bonding arrangements and the installation methods are much the same as the traditional block laying methods. When erecting the corners of block walls built using the thin joint system, it is vitally important to ensure accuracy in the levelling, plumbing and gauging of the blocks. With the thin joint system there is no option of opening up joints to compensate for inaccuracies you might have caused during the build. Once the corners have been erected, the blocks can be run into a line as normal. The thin joint mortar is applied to the blocks using a scoop or a sledge depending on the width of the block (see the descriptions of these tools on page 164). Both tools provide a consistent 2–3 mm layer of mortar across the bed and vertical joints. As the individual blocks are laid, they should be firmly pushed against the vertical, mortared face of the previously laid block and at the same time lowered onto the mortared bed below. It is important to ensure that full joints are maintained at all times to retain the effectiveness and stability of the thin joint system. Where there is a need to tap blocks into place to ensure full uniform joints that are accurately laid to the line, a rubber mallet should be used in order to prevent damage to the blocks. As previously stated, when constructing cavity walls, the inner leaf can be built in its entirety prior to work commencing on the outer leaf. This has a number of advantages: a watertight structure is provided at a much earlier stage of the project partial or full fill insulation can be fitted much more easily and will not be affected by excess mortar protruding from joints wall ties can be fixed once the insulation is in place – the insulation is then secured by the wall tie being driven into the pre-erected blockwork and secured with suitable insulation clips it is easier to keep a clean cavity as the outer leaf is constructed. Key term Perps – the vertical joints between two bricks or blocks Did you know? Bond arrangements for the thin joint system are the same as those used in the traditional brick and block methods Did you know? Where a single skin of walling is built in its entirety and is not supported by other walls, it should be supported or propped up until the mortar has fully set and is sufficiently stable. If this is not done, particularly during adverse weather conditions, the wall may collapse Did you know? Where wall ties are to be driven into the newly constructed inner leaf, it is recommended that the blockwork has been stabilised by the installation of the floor joists at the head of the wall Remember The spacing of wall ties is the same as when constructing cavity walling with traditional methods How to carry out thin joint masonry and masonry cladding Unit 2046 169
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Unit 2046 - Brickwork Level 2 CAA Diploma ... - Pearson Schools

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