EXTERIOR WALL FINISHES FOR TALL BUILDINGS

EXTERIOR WALL FINISHES FOR TALL BUILDINGS

Exterior wall finishes for tall buildings are a very important part of the building. They are responsible for giving the building its uniqueness among other factors such as shape.
They are also very critical in determining the building safety in times of disasters such as earthquakes.
For example, the 1989 Loma Prieta earthquake in San Francisco, U.S.A where 5 people were killed when the brick facade collapsed on the side walk.
In Kenya, we have witnessed the collapse of the Sunbeam Supermarket canopy in 1996 resulting to several deaths.
During a conference on building structures held at Grand Regency hotel, Nairobi in the year 2006, the current Permanent Secretary in the Ministry of Roads, Engineer M.S.M Kamau gave a speech on the role of Structural Engineering in Buildings. He noted that most people assumed that the role of Structural Engineers in Buildings was only limited to the building frame and structure which should not be the case. He said that Structural Engineers have a role to play until final completion of buildings including finishes and gave an example of external wall finishes. He explained that to the layman, external wall finishes such as wall tiles look simple to fix but to the structural engineer, they mean that their self-weight should be taken into consideration and the mechanism of holding the tiles to place carefully structurally analyzed to ensure that they do not fall on passersby below and cause injuries.
He explained that a single tile could be weighing up to 5 kgs of which if not fastened to the wall adequately using the required strength, this could cause serious injuries to passersby below.

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The tiles above are quite heavy and if not structurally designed by a qualified structural engineer to hold in place, can fall on an unsuspecting pedestrian below.

CERAMIC TILES.

Ceramic tiles of various sizes are used to clad the exterior of tall buildings.
As stated above, it’s important that all building industry consultants including structural engineers get involved in the decision to use ceramic tiles on the exterior walls.
Large tiles which are heavier require care infixing to avoid them falling down and casing injuries.
The most used adhesive in Kenya that sticks these tiles to the walls is cement slurry-regularly termed as ‘wet-set’.
Other adhesives are available such as ‘thin-set’. This is a mixture of cement, sand and a chemical called methylcellulose. Methylcellulose holds water allowing the tile to be laid dry.
Organic adhesives.
These are manufactured by Construction chemical manufactures, mostly paint manufacturers and come in pails. These are pre-mixed and come with manufacturer’s instructions on use.

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This building above, which used to be the famous Luthuli Fish and Chips and currently a shopping mall, has ceramic tiles wall finishes in the lobby area.
This building below-Corner House, considered to be the mid-point / centre of Nairobi CBD in Valuation profession circles also has ceramic tile exterior wall finishes.

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The ceramic tiles are the small type. This type poses a minimum risk in injury if a tile falls off since the tile is small and light-weight. This is also easy to repair since only a small portion of tile can fall off at a time compared to a wide sized tile.

GRANITE AND MARBLE TILES

These are quite expensive compared to ceramic tiles. The advantage is in the aesthetics. Granite and Marble looks very appealing to the eye. Granite and Marble tiles also require little or no maintenance since these are naturally occurring.

From NAIROBI CBD BUILDINGS

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The building above, located along Kenyatta Avenue has Granite tile wall cladding.
The main difference between Granite and Marble is the appearance. Granite is mostly gray in color and contains tiny specs and dots due to its igneous formation when hot lava cools off.
Marble appears in several colors and shades with colored streaks showing the sediments in the initial rock formation.

PAINT ON CEMENT SCREED PLASTER

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This method is relatively lower in cost compared to Ceramic, Granite and Marble tiling.
A good example is the KENCOM building along Moi Avenue.
This method requires minimal maintenance, only the periodic painting. Painting on such surfaces requires specialized expertise in terms of supporting structures for the painters to stand on.
The advantage is that its easy for the building owner to easily change the color in case of rebranding as opposed to tile finishes.

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COLOURED TEXTURED CEMENT PLASTER

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This type of wall finish makes it easy to have a combination of colors and textures on a facade.
A good example is the Emperor Plaza building along Koinange Street.
Its quite costly compared to paint on cement plaster and ceramic tiles.

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Textured cement comes in various textures.
Some paint manufacturers also offer a similar type of rough textured exterior paint.

PATTERNED REINFORCED CONCRETE

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This type of exterior finish gives a unique appearance.
Such an example is K.I.C.C. Building and the Hilton hotel.
The ballast component in the reinforced concrete is carefully selected to the right size so as to leave the ballast-dotted outward finish.

HAND-DRESSED MASONRY WALLING

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This type of finish is common in the buildings constructed in the early 1900s.
Currently, very few new buildings have this type of finish. This is because hand-dressing masonry stone takes alot of time and hence expensive in terms of labour costs. Most of these buildings were built during the colonial period whereby labour was virtually free since the colonies could have the natives work at little or no pay.

This type of finish is long lasting as can be attested by Kipande House, which has stood the test of the test of time.
Currently, there is availability of polished natural stone tiles in the market such as the tiles on the walls of the former U.S.A Embassy at Moi Avenue.

BRICK CLADDING

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This type of finish is very long lasting, requires little or no maintenance and very cost =effective.
Such an example is the Stanbic Bank House along Kenyatta Avenue.
This type of finish gives the building a unique and natural feel.

GLASS

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Glass facades make a building look modern. This type of all finish is cost-effective in that it acts as a building element [wall] and at the same time acts as the wall finish.
Disadvantage is mainly due to letting in heat and glare from the sun. This problem is usually solved by using a tinted toughened thick glass and adding window film to its surface.

CONCLUSION

There are many types of wall finishes for tall buildings available in the market locally and internationally. It’s up to the owner of the building to liaise with their Architect ,Structural Engineer, Quantity Surveyor and other relevant professionals in their Building Design team to choose the most appropriate wall finish.

Francis Gichuhi Kamau
Architect.
www.a4architect.com