JOINTS in SURFACE FINISHES

Post 469 by Gautam Shah

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stone joints

Joints are very important section of a surface finish. Joints create pattern, texture, contrast, equalize variegated colours of the surface, endow a discipline and unity, create an orientation, divide a space into proportioned sets, provide flexibility, prevent or direct cracking. A surface finish gains its value as much for the quality of the surface as the careful design consideration for the joints.

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Joints in surface systems arise as the components of the surface finish has smaller size than the space, fixing becomes easier, of assurance of adhesion, and to help divide the task in lots. Surface-finishes are applied as coatings with on-site application, also need scheduled joints to manage continuity. Such depositions, though known as seamless or joint-less system, have nearly imperceptible joints. These joints always have some inherent drawbacks of quality or consistency.

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Designing a joint in surface system is a followup process once the surface components have been devised or accepted. In a good design Joints are never of secondary importance. In creation of assembled entities joining is an integrated effort. For all systems joining, un-joining and rejoining, are important strategies of design.

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Joints occur with or without a material in an assemblage Fused joints (by chemical solution or heat fusion) have a traceable joint. Edge to edge joining is, both created and avoided intentionally. Wooden floorings for decks (exterior) and performance stages (interior) have spaced joints to allow the wood to adjust to the changes in moisture content of air. Similarly metal assemblies have free joints to accommodate the expansion caused by the temperature. Edge joints have an intervening material (such as a ductile or conductive material) or none, to allow or curtail the transmission of energy and vibratory forces (mechanical, sound, electrical, etc.). Structures require separation joints to sustain their integrity, and the same are identically placed in their surface finishes.

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Very closely placed joints create a virtually continuous surface finish. Stone masonry and wood often have very thin or knife edge joints. Thin joints are for sensorial reasons like touch, fill, visual, etc., and for structural or functional causes. Thin joints provide some flexibility to the surface component, but there is insufficient space for displacement such as in bricks and cobble stone flooring.

Applying_grout

Widely spaced joints occur for many different reasons. The prime reasons are: non matting planes at the joint, geometric deviations of the surface components’ shapes. Deep joints require greater width for filling up. Wide unfilled or shallow filled joints create crevices, enhancing the light-shadow contrast over the surface

Saw_Cut_Control_Joint_in_Concrete

Bricks, Stone and Blocks masonry surfaces have etched joints called pointing, these enhance the visual texture of the surface due to shadows of the depth, or deposition to form rendered joints. Such joints are formed of matching or different materials and colour. The deep etched  joints allow space hair cracks.

Brick Pointing

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HISTORICAL WALL FINISHES

Historically Greek architecture created pristine walls with coursed masonry. Romans created concrete walls with built in lining and a variety of stone facings. Roman walls in interior were plastered with marble powder and polished to a very glossy finish. Walls were decorated and painted by stucco system. Marble and glass mosaic in figures and patterns were applied on walls.

Byzantine walls were finished the same way, but unlike the flashy colour scheme of Roman villas and thermae, were simpler. Byzantine buildings used marble and mosaic bands running across the interior walls. Egyptian painted the interiors with their limited tonal vocabulary but using gilding extensively.

Babylonians used ornamental polychrome brickwork, often with low relief work. In early Gothic period walls were being flooded with light so the structural definitions were very important, rather than the wall treatment. Wall ornamentation was like the tracery pattern employed in windows. Panellings were used at lower levels of otherwise tall rooms. Gothic period also saw introduction of external non load bearing or partition wall. In buildings other than church walls did not require such vast openings. Areas between openings in interior and exterior began to form into alcoves or niches to filled in with statuettes.

During Renaissance these intermediate wall areas were highly rusticated. Windows were visually enlarged by decorative appendages. A modulated vocabulary of alternating wall and window treatment was established. However, these vocabularies did not evolve across the floor except by repetition.

Post Renaissance period saw entire facade wall being designed as one unit overcoming the horizontality of floor divisions and straight roof lines. Facade walls now became undulating not in the plan but also in elevation. Japanese shoji partitions serving the purpose of door, window and a divider inspired many architect in early 20th century to design interiors with relocatable partitions systems. Space and bubble structures dissolved the wall as a definition.