Friday, April 11, 2008

SPECIALIZED RENDERING

Introduction:-
The words wall, walling, cladding, facings and wall facings are variously used relative to the usually vertical envelop of the buildings.
Cladding clothes the building in a protective clothing that is hung supported by or secured to the skeleton or structural frame as a jacket.
Cladding will be used to describe panels of concrete, GRC, GRP, glass & metal fixed to and generally hung from the frame, by supporting beams or inside light framing as a continuous outer skin to the frame.
More recently thin sheet metal panels, are used by themselves as a wall finish or with the frame and services exposed in what is referred as a hi-tech architecture.
In specialized external finishes the following techniques are generally used-
Aluminium cladding
Stone cladding
Heritage plaster

Aluminum cladding:-
In this aluminium metal panels are used in the form of separate flat or profiled panels supported by a metal carrier system which is fixed to the structure.
These panels are separated either by visible silicon joints or by visible members of their supporting frame.
The aluminium panel is a composite material composed to two strong sheets of .020" gauge aluminum and a polyethylene core. It is lightweight, rigid, and corrosion resistant. It is easily fabricated and can be used for a wide variety of applications.

Aluminum cladding:-
These panels are available in the following standard sizes-
SIZES 1220mmX2440mm, 1220mmX3050mm, 1220mmX3660mm.
THICKNESS
2mm, 3mm, 4mm, 6mm.
Special sizes are available as per order. In addition to this, larger widths of 1550mm & 1600 mm are available.




Joining of panels:

Fastening: Riveting & Bolting:
Aluminium blind rivet & stainless steel bolt/nuts are recommended to fasten Al panels.

Welding:
Aluminium panels edges can be joined by welding the core with the help of hot jet gun.




INSTALLATION DETAILS:









Characteristics:

Excellent flatness.
Minimum dead weight.
Consistency of paint finish.
Resistant to blow & breakage.
Weather ability or vibration damping.
Sound & heat insulation.
Ease of formability.
Ease of installation & maintenance.

Stone cladding:-

Stone facings are provided for a decorative finish to stimulate the effect of solidity and permanence traditionally associated with the masonry.
The types of stones used are limestone, Clipsham, Sandstones, Marble etc.
Facing slabs are fixed so that there is a cavity between the back of the slabs and the back ground wall or frame to allow fixings and tolerances. The type of fixings used to support and secure facing slabs in position are:
Loadbearing fixings
Restraint fixings
Combined loadbearing and restraint fixings.
Face fixings
Soffit fixings

Joints between stone slabs:-
Joints between stone facing slabs should be sealed as a barrier from rain water running off the face of the slabs.
Whenever water enters the cavity it will be trapped and will not evaporate and may cause conditions of persistent dampness. Open or Butt joints must be avoided.
For joints between limestone & sandstone- mortar of cement, lime, sand mix 1:1:6.
For joints between granite- mortar mix of 1:2:8.
Sealants may be also used such as 1 part polysulphide, 1 part polyurethane.

Heritage plaster:-

Heritage plaster is the brand name given to a certain type of plaster.
It is a wall finish used to
give a textured finishes to
external and internal walls
Its available in the form of silica granules or flakes, to be mixed with a bonding agent.
It requires minimum 8 hours to dry, as 50% of the liquid is absorbed by the base, and 50% evaporates.
A silicon coat is applied as a top finish.
This plaster lasts for about 15-20 years ,as long as the smooth plaster base for it doesn’t crack.
It requires skilled labour, often provided by the manufacturers, to ensure product quality.

Advantages:-
This wall finish is durable, and lasts about 15-20 yrs, (given that the smooth plaster base behind it doesn't crack.) compared to cement paint, which needs to be reapplied externally every 3 yrs.
No further primer and paint is required over it
Various colors are available in heritage plaster.
Its weather resistant, easily washable and not prone to fungus, as cement paint is.

Disadvantages:-
Its quite expensive ( Rs.30-150 / kg of granules) compared to cement paint finish.
It requires skilled labour supplied by the manufacturer.
It has to be bought from authorized distributors.

Applications:-
Being weather resistant and durable, its preferred over cement paint for external walls.
It is often used to create interesting murals or designs with the large no. of colors and textures available.

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