Basement

Maintenance

It is almost impossible to make basements 100% waterproof. Defects usually surface up in later stage due to changes in environmental conditions such as rising ground water, sump effect of excavation, differential settlement etc. The major critical elements such as RCC structure, positive waterproofing or waterstops are often beyond regular inspection and maintenance. Defects pertaining to these elements demonstrate visible signs on internal finishes. Hence the main aim is to locate any sign of leakage or dampness as early as possible by monitoring the internal environment during post occupancy period. For finishes, cleaning methods and equipment should be specified by material supplier or cleaning specialist. Cleaning frequency is planned for aesthetics, durability and performance.

Grading for maintenance

Factors	Criteria to consider for grading			Grade
Maintenance practise	1. Maintenance of drainage system and finishes as per following guideline. 2. Full inspection of basement (seepage, dampness, RH, mould growth, soiling) at least once in a year and after each heavy downpour. 3. Thermo-graphic imaging once a year to detect any subsurface leakage. 4. Proper record maintenance of leakage history in terms of location and causes. E.g. if leakage takes place after each rainfall, cause is to be noted as poor surface water runoff.			5
	1. Only cleaning and visual inspection. 2. No thermographic imaging or record keeping			3
	Repair / cleaning only when condition is beyond acceptance level.			1
Soil permeability (ISE, 2004)	Higher the permeability, higher is the chance of seepage (ISE, 2004).
	Permeability (cm/s)	Example	Remarks
	10-9 −10-6	Clay	Low	5
	10-6 −10-4	Silt, sandy silt, clayey sand	Relatively low	4
	10-5 −10-3	Silty sand, fine sand	Moderate	3
	10-3 −10-1	Fine gravel, gravely sand	Moderately high	2
	10-1 −1.0	Gravel	High	1
Presence of sulphate & aggressive chemicals	Presence of sulphur or chloride, acidity, contaminant, gas, radioactive material etc in high concentration can damage the basement and its waterproofing.		Mild	5
			Moderate	4
			Severe	3
			Extreme	2
			Other unusual condn.	1
Depth	Higher depth means higher hydrostatic pressure & higher risk of seepage. Deeper basements usually house complex services & tough to maintain.		Shallow: <2 storey	5
			Deep: 2-3 storey	3
			V deep: > 3 storey	1
Age of the building	< 5 years			5
	5 – 10 years			4
	10 – 20 years			3
	20 – 30 years			2
	> 30 years			1

Guideline for maintenance of internal and cavity drainage

Elements	Condition	Cleaning method	Freq.
Check	1. Condition of drainage system. 2. Functioning of emergency maintenance services (e.g. pumps) and automatic alarm system to notify pump failure.		4x/yr*
Clean	1. Drains and sumps.		4x/yr*
	1. Internal cavity (if possible)		2x/yr

* Should also be done after major downpour.

Guideline for cleaning of finishes on floor and walls

Elements	Condition	Cleaning method	Freq.
Flooring	No oil / grease		Sweep: daily, Wash: weekly, Scrub: monthly
	Grease stains	Aqueous soln. of alkaline salts (caustic soda, sodium meta-silicate, tri-sodium phosphate or appropriate proprietary detergent etc).
	Sealant deterioration	Clean joints and reseal with hard sealants. e.g. synthetic resin composite. Movement joints need flexible sealant.
Ceramic tiles	Light soiling	1/4 cup low-suds detergent / 1-2 tbsp. washing soda or tri-sodium phosphate mixed in 1 gallon of water. Else commercial tile cleaning powder or neutral cleaner.	2x/yr
	Deep soiling / hard to reach	Mild detergent solution.
	Severe soiling	Scrubbing with acid / alkali based cleaner
	Efflorescence	Commercial tile cleaner
	Mildew	Diluted chlorine bleach /mildew-retardant spray
	Biological growth	Scrubbing with acid / alkaline based cleaner. Biocidal washes may be applied to prevent further growth
Plastered & painted wall finish	Light soiling	Wash with water and mild detergent
Plastered & painted wall finish	Severe soiling	Wash with strong alkali solution, e.g. 2 tbsp. ammonia/tri- sodium phosphate or detergent in 1-gallon warm water.