External Tanking
(Identify the most appropriate RIW product(s) for your specific application from the text below and click on the product icon on the right to access the product page for more information and downloadable data sheets).
External tanking is the provision of a waterproof membrane to the outside of the basement or sub-structure in accordance with BS8102:1990 (Type A form of construction). When selecting a suitable external tanking system, consideration should be given to the form of construction, ground water levels, ground drainage, soil type and ground contamination.
Generally, waterproof membranes are installed onto a horizontal
concrete blinding and vertically to reinforced concrete
or masonry sub-structures. Boundary line construction
applications, including secant piling, contiguous piling
and sheet piling, create challenging substrates and
therefore some waterproof membranes will not be deemed
suitable, due to factors such as the need for excessive
surface preparation. Sub-soil drainage systems should
be incorporated into the design, where required.
In areas where the water table is classed as “High”, please consult the RIW Technical Department.
RIW LAC, a two coat bitumen solution, BBA approved as an external tanking membrane, which has been used as such for over 80 years. However, RIW Flexiseal is a high performance alternative, with its colour coded quality control system and excellent flexibility making it especially suitable for masonry structures.
RIW Sheetseal
226 is also widely used as a horizontal external
tanking membrane. Large areas may be applied quickly
with no drying time, especially to horizontal surfaces.
Using a combination of membranes, for instance, RIW
Sheetseal 226 horizontally and RIW
Flexiseal vertically, should always be considered
to achieve the ideal design.
RIW Structureseal is a pre-applied system used in boundary line construction applications including secant piling, contiguous piling, sheet piling and is ideal for challenging site applications, and where other systems may not be deemed suitable due external factors such as accessibility, site geology or inclement weather.
RIW Waterstop should be incorporated in all construction joints in reinforced concrete sub-structures. | 
