Internal 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).
Internal Tanking is the provision of a waterproof membrane to the inside of the basement or sub-structure in accordance with BS8102:1990 (Type A form of construction). When selecting a suitable internal tanking system, consideration should be given to the form of construction, ground water levels, ground drainage, soil type and ground contamination.
When Internal tanking with applied membranes, you must allow for hydrostatic pressure acting upon the membrane, and therefore a ‘loading coat’ is required. 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 internal tanking membrane, 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 can also be used as an internal 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
Cavity Drain is another type of system used to internally
tank basements, ie: ( Type C form of
construction ) - See also “Drained Cavity Systems”.
The system is a HDPE profiled sheet, which is mechanically fixed to the walls, and laid on the slab under a 65mm min. screed. The RIW Cavity Drain will allow water to pass through the retaining wall, into the cavity former, where it may be channelled away to a sump with a pump or other suitable drainage outlet. This system does not require a ‘loading coat’ to the vertical surface. It is suitable for use if the water table is high, and does not require additional external land drainage. Also surface preparation is far less critical than the requirements for applied membranes.
RIW
Toughseal can be used internally below ground level
in conjunction with other forms of waterproofing. Please
consult the RIW Technical Department for site specific
advice. | 
