Environmental Grades for London Basement Construction Explained


August 19th 2016 | Back to news

Environmental grades on basements in London are used to define levels of ‘dryness’, within a given basement or cellar. Though this might sound complicated, it's actually as easy as 1, 2, 3; meaning a grade 1 environment is wetter than a grade 3 environment.

These grades are defined within British Standard 8102 (2009) Code of practice for protection of below ground structures against water from the ground. As a ‘code of practice’ the British Standard is the primary waterproofing design guide which we refer to, when considering basement construction. The grades give us an indication of how and where a basement can be dug, what tools need to be used, what type of waterproofing is best, as well as indicating any problems that may arise during construction, so we can be prepared for every eventuality.

Grade 1

A building that is Grade 1 rated means that some amount of damp or leaking is allowed. This restricts the structure to usage as a car garage, plant room, or workshop, as long as no electric cables are at risk of getting wet.

It should be noted that this is the only grade of structure that can have water seepage, the other two grades must be watertight to pass inspection.

Grade 2

As listed within BS8102, Grade 2 requires no water leakage, but some damp is allowed. This means that condensation may build up and the room is only suitable for use as a plant room, workshop or storage room where a dryer environment or the use of electricity is needed. Some ventilation may be required if the room is going to be used frequently to avoid damp and mould problems.

Grade 3

Grade 3 is your standard basement room. It can be used for any function – bedroom, office, restaurant, shop, gym, playroom. It is completely waterproof, no water should leak in and no damp should appear. It should be well ventilated, heated and dehumidified. If the room is to be used as a kitchen or bathroom, extra ventilation will be required to ensure that no damp is let into the structure.

It's that simple.

Your architect and construction team will be able to decide which grade your building needs to adhere to, depending on the final scope of your basement conversion, but to put it simply – grade 1 allows some water to leak in, grade 2 allows no water but some damp, and grade 3 is completely dry and suitable for any purpose.

To find out more about these environmental grades, or to enquire about a retrofit basement on your home or business, visit our website or contact Knowles on 01344 886 898.

Environmental Grades for London Basement Construction Explained