considered for additional security in particularly sensitive areas, or where there are extremely stringent basement waterproofing requirements, especially where remedial works to stop leaks, or future waterproofing repairs are not easily possible due to access or other factors. (i.e. Type A + Type B, Type B + Type C, Type A + Type C, etc.)

The basement structure’s movement joints, construction joints and the areas around pipe entry’s or service ducts must always be given special consideration with all possible waterproofing strategies, including specific detailing solutions to meet specific requirements. NCC's Basement Waterproofing Specialists understand the importance of all of these requirements and can assist you in integrating the appropriate procedures and details into a complete basement waterproofing system, of whichever type is determined to be the most appropriate and cost effective for your project.

For more details on specific waterproofing techniques and specific waterproofing products and systems please go to our general ‘Basement Waterproofing Products’ pages or for Tanking solutions, to our ‘Basement Tanking Products' pages.

For more information on the different types of basement waterproofing products and systems available and their classification in accordance with BS 8102: 2009 is outlined in the tables and notes below:

The Selection of Different Waterproofing / Ground Water Protection System Types According to the Water Table Risk Classification.

(Based on BS 8102: 2009)

Risk Associated with the Water Table Level	Water table Classification (see Notes below)	Waterproofing Protection Systems
		Type A Barrier Protection	Type B Integral Protection		Type C Drained Protection
			Piled Walls	Reinforced concrete wall to BS EN 1992
Low High	Low	Acceptable	Acceptable	Acceptable	Acceptable
	Variable	Acceptable if the "variable" classification is due to surface water. Then specific product / system / detailing recommendations are also required.	Acceptable where: a) the piled wall is directly accessible for repair and maintenance from inside the structure; or b) the piled wall is combined with a fully bonded waterproofing barrier; or c) the piled wall is faced internally with a concrete wall to BS EN1992.	Acceptable	Acceptable
	High	Acceptable when: An appropriate cement based multi-coat render system (such as Sika-1 pre-bagged system) or cementitious coatings (such as SikaTop Seal 107 or Remmers Sulfatex Grout) are used; and the wall is of concrete in accordance with BS EN1992		Acceptable	Acceptable
Measures to reduce risk		Use a combined protection system Incorporate appropriately designed sub-surface drainage and ensure that this is maintained Use a fully bonded waterproofing barrier Lower the permeability of the main structural wall Use water tight concrete with a waterproofing admixture, such as Sika-1 in accordance with BS EN 934 Ensure that discharge systems, e.g. pumps etc, are maintained so that the system remains effective
NOTE The water table classifications are defined as follows Low - where the water table or perched water (unpressurized water held above the water table by impermeable rock or sediment) is assessed to be permanently below the underside of the base slab. This only applies to free-draining ground and strata. Variable - where the water table fluctuates. High - where the water table or perched water table is assessed to be permanently above the underside of the base slab. Ground permeability and slope should also be considered as this might also affect the level of risk under a low or variable water table.

Table 2: The Different Grades of Below Ground Basement Waterproofing Protection according to BS 8102: 2009 Revised,

are defined as:

Grade	Typical Areas of Use in Building and Structures	Waterproofing System Performance Level Required
1	Car parking; plant rooms (excluding electrical equipment); workshops etc.	Some seepage and damp areas are tolerable, dependent on the intended use. Additional local drainage might be necessary to deal with seepage water.
2	Plant rooms and workshops requiring a drier environment than Grade 1 i.e. storage areas etc.	No water penetration is acceptable. Damp areas tolerable; additional ventilation might be required to remove vapour.
3	Ventilated residential and commercial areas, including homes, offices, restaurants, leisure facilities etc.	No water penetration acceptable Ventilation, dehumidification or air conditioning may be necessary, appropriate to the intended use.

Important Notes:
The previous edition of BS 8102 (1990 edition) also referred to additional classification of 'Grade 4 Environments' for the waterproofing of basements where absolutely no water or water vapour penetration was permitted. However; Grade 4 has not been retained in this latest revision, as its only difference from Grade 3 was its performance level relating to protection against water vapour penetration that could include ventilation, dehumidification or air conditioning in the event of water vapour penetration.

However this would normally be achieved post-construction, by the application of additional vapour tight coating systems, such as impermeable epoxy resin coatings such as Sikagard 62. Therefore the structural design and construction requirements for Grade 4 were effectively also the same, or extremely similar to those of Grade 3. As a result there is no longer a ‘Grade 4’ as such, plus any requirements to prevent or reduce water vapour penetration must be specified and detailed separately in the design and detailing process.

Table 3: The Categories of and Products that are included in the Classification ofof Type A Waterproofing Barrier Materials

(According to BS 8102: 2009)

Type of Waterproofing Barrier Protection	Waterproofing System Description	Relevant Waterproofing System Standards	Method of Waterproofing System Application
Bonded sheet waterproofing membranes	Bitumen-based, sheet membranes can be: - cold-applied (self-adhesive);or - hot applied ("torched-on" or bonded using a hot bitumen adhesive) - increasingly reducing in popularity due to the potential fire / flame hazards and additional site insurance cost. Not recommended by NCC.	BS 743:1970, Class A or BS 8747	Can be applied externally or sandwiched.
	Composite sheet membranes.(traditionally bitumen based but also newer technology HDPE – High Density Poly Ethylene, and increasingly FPO – Polyolefin based materials).		Can be applied externally or sandwiched.
Liquid applied waterproofing membranes	There are different types of liquid applied membranes, which include one component materials (usually bitumen or polyurethane based) and higher performance two component systems. e.g. Remmers Profi Tight	-	Can be applied externally or sandwiched
Geosynthetic (bentonite) clay liners	These are traditional and comprise 'bentonite' a type of clay with a ‘carrier’ material, typically of geotextile or high-density polyethylene. There are two principal forms: dry bentonite and pre-hydrated bentonite. Can be problematic when used in variable water tables due to problems with wash-out and between wetting and drying out which is not reversible. Not recommended by NCC	-	Can be applied externally or sandwiched
Mastic asphalt	Applied in three coats as a hot liquid. These systems are also now becoming less popular due to fire risks and insurance costs etc. Not recommended by NCC	BS EN 12970	Can be applied externally or sandwiched
Cement Based crystallisation slurries and powders	These are applied as impregnating coatings or slurries to surfaces of concrete walls and slabs. NCC does not consider these materials completely effective alone, unless they are used in combination with an additional layer of crystalline render or slurry coating system.	-	Can be applied internally or externally.
Cement Based multi-coat tanking, renders and coatings	These are generally applied in multi-coat renders or slurries and are resistant to liquid water, but will allow some water vapour penetration e.g. Sika 1 System, Remmers Sulfatex Grout and SikaTop Seal 107.	-	Can be applied internally or externally.

For specific advice in selecting the right type and classification of waterproofing system for your project, please contact any of our offices (details on the left of this page) and one of our waterproofing specialists will be pleased to assist you.