Basements: Waterproofing 2 BASEmENT uSAGE Table 1 relates environmental performance levels to basement usage, and defines them from Grades 1 to 3. Most basements will be for domestic accommodation, which is Grade 3. Grade 1 environment can from BS 8102 be suitable. BS 8102:2009 Code of practice for protection of below ground structures against water from the ground (British Standard) Available for Subscriptions. Content Provider British Standards Institution [BSI]. Documents sold on the ANSI Standards Store are in electronic Adobe Acrobat PDF format, however some ISO and IEC standards are available. ![]() BS 8102 Table 2 (BS 8102:2009 ‘Code of practice for protection of below ground structures against water from the ground’) is shown below and gives guidance as to the performance required from structural waterproofing; depending on the intended end use the basement. Within this blog I try to explain this important document more clearly using an excerpt from the referenced ICE document. BS 8102 Table 2 This table quantifies the waterproofing performance required by ‘seepage’ (or ‘water penetration’) and ‘damp areas’. How exactly does one define those terms? ICE Specification The above table references the ‘ICE Specification for piling and embedded retaining walls’. The following is an extract: The following definitions apply for this Specification: • Watertightness Assessment Level (WAL) is the lowest level visible on the front face of the wall at the time of a watertightness assessment. • Damp patch: when touched, a damp patch may leave a slight film of moisture on the hand, but no droplets of water or greater degrees of wetness are left on the hand. On a concrete surface a damp patch is discernible from a darkening of the colour of the concrete. • Beading of water: beading of water is the state in which individual droplets of water (held by surface tension effects) form on the surface of the wall and adhere to the wall. Fx plus network. The water beads do not coalesce with each other. The beads remain stationary on the surface and do not flow. • Weeping of water: weeping of water is the state in which droplets of water form on the surface of the wall and coalesce with other droplets. ![]() The coalesced water does not remain stationary on the wall surface, but instead flows down the wall. Neither a wall element nor joint between elements shall be considered watertight under this Specification if the following criteria are not met: 1. No weeping of water or greater rates of water ingress or flow is visible between the top of the wall and the WAL. Beading of water is permitted. Damp patches on the front face of the wall are permitted provided that all the following criteria are met: (i) the total area of dampness does not exceed 10% of the visible area of the front face; (ii) no individual patch of dampness has an area in excess of 4 m. It seems that the most awkward issue within the categorisation of waterproofing performance within BS 8102 Table 2 is the word ‘damp’.
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