Façade

Maintenance

A well-planned maintenance strategy can enhance the service life and aesthetic quality of a façade to a great extent. Apart from conventional materials, modern finishes on façade are myriad. Hence the cleaning, inspection method and equipment should be selected as per manufacturer or any other competent party. A proper cleaning tool, method and interval is important as per relevant guidelines such as BS 8221, BS 5385, BS 6270 etc. General guidelines based on relevant standards are presented in the following section.

Exposure of a building to the environment affects the rate of deterioration. Older the building, longer is the exposure along with normal aging. Older building may also have the limitation of less advanced façade systems and access provision. Regarding height, a low-rise building is usually subjected to a much reduced effect of wind driven rain and ultraviolet radiation than tall buildings since it would very likely be sheltered by its surrounding taller buildings. In the macro-environment, buildings located within different zones such as industrial, urban, rural or coastal are subjected to different concentrations of atmospheric pollution. Hence these external factors were counted for generating maintainability score.

Grading for regular maintenance of façade

Factor	Grading criteria		Grade
General maintenance	As per maintenance practices guideline for cleaning. Thermographic imaging once a year to detect any sub-surface leakage. Full inspection (seepage, dampness, RH, mould growth, soiling, corrosion etc) as recommended. Any problem due to ancillary facilities (e.g. structural issues) should be noted and the concerned maintenance person should be informed.		5
	Only regular maintenance of finishes No other action taken.		3
	Cleaning and inspection are not done as per guideline		1
Age	The older the building, the more likely are the occurrences of defects. The durability of replaced materials may not be as long as materials those that are originally installed. Therefore, the grading is a factor to the maximum age of 30, assuming design life is 30 years.		1-5
Height	The taller the building, the costlier will be any repair, cleaning and replacement work. There are more safety issues to be considered and access systems will have to be more elaborate in order to overcome higher wind speeds. Moreover, exposure to UV rays and driving rain attacks more harshly.	1-4 storey	5
		5-12	4
		13-40	3
		41-60	2
		>60	1
Location	The general location of building affects the rate and extent of deterioration of the façade. An area, where direct pollution is mild, the façade is expected to require less maintenance works than if it is located within a heavily polluted or coastal region. Detrimental acid rain is expected in highly polluted areas.	Rural	5
		Sub-urban	4
		Urban	3
		Coastal (50m proximity)	2
		Industrial	1

Guidelines for maintenance of exposed brick wall

Condition	Cleaning method	Freq.
Dirt stain on texture:		Clean: 1x/yr.
Smooth	Scrubbing with scouring powder and stiff brush. High-pressure steam (<60 psi) with detergent.
Moderate rough	Scrubbing with an oxalic acid-ammonium bi-fluoride solution.
Very rough	Pressurized water cleaning (< 700 psi).
With coloured mortar joints	Mild detergent solutions. Acids may bleach coloured mortar.
Biological stain	Apply sulpharnate or weed killer.
Green Stains from vanadium salts	Flush with water and next with dilute hydroxide of potassium / sodium. Allow it to stand for 3 days. Hose off remaining salt.
Paint on wall	Chemicals & high-pressure steam or scrubbing with steel wool.
Walls with efflorescence	Generally, disappear with normal weathering. Can be removed by dry brushing or with clear water and a stiff brush. Heavy accumulation requires proprietary cleaner.
Greyish- white haze (White scum)	Masking by solutions of paraffin oil and Varsol, or linseed oil and Varsol, applied by brush to the affected brick units.

Guidelines for maintenance of concrete and plastered wall

Condition	Cleaning method	Freq.
Light soiling	Low-pressure water sprayed from top down to moisten dirt deposits followed by hosing down with brushing.	Clean: 1x/ yr
Deep soiling & hard to reach areas	Jetting with v. high pressure (5000-10000 psi) & flat-fan pattern nozzle Live steam cleans effectively without damaging the surface. Brushes & abrasives may be used to help to remove the dirt.
Severe soiling	Chemical cleaning: ammonium hydroxide, sodium hypochlorite or hydrogen peroxide can be used. Saturating the surface with water before applying the acid solution and flushing it thoroughly reduce etching by acidic agents. Mechanical cleaning: power tools (grinder, buffers, chisels, brushes), steam/ flame cleaners. Flame cleaners can burn off organic stains that do not respond to solvents.
Efflorescence	Scrubbing with water. Hosing with high pressure water jet. Concrete should be rinsed thoroughly with water after removal of efflorescence. Diluted acids may be useful.

Guidelines for maintenance of painted wall: gloss/semi-gloss enamels

Condition	Cleaning method	Freq.
Light soiling	Washing with water and mild detergent (erg. Hand wash / dishwasher liquid), or a mild commercial household cleaner.	Clean: 1x/ yr Repaint: 1x/ 5yr
Heavy soiling	Washing with a stronger alkali solution. E.g. 2 tablespoons ammonia/ 1 tablespoon trisodium phosphate or 2 tablespoons laundry detergent in 1 gallon warm (not hot) water). Rinsing. Stronger solutions may remove some of the paint.	Clean: 1x/ yr Repaint: 1x/ 5yr

Guidelines for maintenance of tiled wall

Material/ Condition	Cleaning method	Freq.
Unglazed ceramic tile	Scrubbing with washing soda (tri-sodium phosphate). Rinsing.	Clean: 1x/yr. Visual inspect: 1x/yr. Thermographic testing: 1x/ 5yr
Glazed ceramic tiles	Washing with plain water to remove soil. Mild detergent solution for occasional heavy soil. Rinsing.
Mosaic tiles	Abrasive cleaner such as brushing can be effective. Pressure blasting can remove dirt trapped at joints.
Efflorescence	Dry brushing or with water and a stiff brush. Heavy efflorescence is removed with muriatic acid and scrubbing a wetted surface.
Mildew	Washing with a dilute solution of chlorine bleach in water.
Biological growth	Washing with a weak acid such as vinegar.

Guidelines for maintenance of natural stone wall

Cladding stone	Cleaning method	Freq.
Unpolished Granite	Mix of hydrofluoric and ortho-phosphoric acid for cleaning. Caustic soda cleaners should not be used.	Clean: 1x/yr Inspect & maintain: As /BS 5427-1
Polished granites	Washing with clean water and a mild liq. detergent. Rinsing.
Polished Marble	Acids, phosphorus, chlorine or scouring powder is harmful. Hard water will encourage discolouration particularly if iron is present, and cause insoluble salts build-up. Re-polishing may be required on a regular basis.
Stones with efflorescence	Dry brushing or with water and a stiff brush. Heavy efflorescence is removed with muriatic acid and scrubbing a wetted surface.
Biological stain	Biocidal washes to control biological growth for short period.

Guidelines for maintenance of glass (curtain wall & window)

Condition	Cleaning method	Grade
Soiled and grease marks	Cleaner: alkali such as ammonia or baking or washing soda. A cloth, sponge or chamois dipped in cleaner is squeezed almost dry before wiping the glass surface. The wet surface is dried with newspapers, paper towels, window wipes or chamois. Windows should not be washed under direct sunlight because they tend to streak and are more difficult to clean.	Clean: 2x/ yr. Inspect: 1x/6 month for > 25% of glazed area
Hard water deposits & soil	Cleaning with a weak acid such as vinegar. A strong acid would etch the glass.

Guidelines for maintenance of metal cladded wall

Condition		Cleaning method		Freq.
Aluminium (anodized)				Clean: 1x/ 3 month (polluted / marine area) Else 1x/6 month Inspect: 1x/ yr. Redecorate: 1x/10-15 yrs
Light soiling	Flushed with water at moderate pressure. Concurrent brushing or sponging with mild detergent.
Heavy soiling	Scrubbing with nylon-cleaning pad wet with surface protectant material. Rinsing with water and wiped dry with chamois, squeegee or lint-free cloth. Air drying is also fine. Power cleaning tools (e.g. air-driven reciprocating machine fitted with abrasive pads) and mild detergent can also be used.
Aluminium (powder coated)
Light soiling	Flush surface with water at moderate pressure. Concurrent brushing or sponging with mild detergent may be needed.
Heavy soiling	Mild solvent (e.g. mineral spirits) may remove grease, sealant or caulking compounds. Diluted muriatic acid (<10%) removes dried concrete stains. May require vigorous rubbing with non-abrasive brush or plastic scraper.
Steel
Dirt and pollution	Rinsing with warm water and mild detergent. Rubbing in the direction of the grain with sponges, fibrous brushes, or plastic pads. Steel wool/ brushes will cause pitting and should not be used. Minimum rubbing and wiping to avoid scratches on finishes.
Chlorides	Cleaning with warm water.
Fingerprints, grease, oil	Cleaning with combination of water, mild detergent and mineral spirits.
Rust stains	Rusted elements (bolts, screws) are removed and dipped in nitric acid.
Graffiti	Water-soluble inks: cleaning with warm water, non-ionic detergent or and mineral spirits. Lead pencil markings: Any oily cleaner such as paste wax.
Weld stains	Cleaning with mild abrasive cleaner in paste form and water.
Corrosion products	Removed with warm water, detergent, and plastic pads. If severe corrosion, mechanical methods (e.g. grinding or sandblasting) are used. Refinishing with fine abrasive can restore surface to original condition.
Any metal in general
Biological staining			Fungicide is left on wall for up to 7 days. Thoroughly removed and rinsed with water to remove traces of fungicide and effluent.
Fungus , dirt in sealant			Brush with warm dilute detergent solution. No solvent bleach or abrasive unless permitted by manufacturer. Cleaning of surrounded areas with harsh method or material (e.g. grit blasting, acid washing, high pressure hosing of stones may be detrimental for the sealant.	Clean: 2x/ yr. Inspect:2x /yr for > 25% area