I’m a homeowner

  structural waterproofing for homeowners



IT’S AS EASY AS 1,2,3…

Environmental grades (1 to 3) are used to define levels of ‘dryness’, within a basement, with a Grade 1 environment essentially being more ‘wet’, than a Grade 3 environment.

The first thing to understand is that 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 waterproofing design specialists should refer to, when trying to keep your underground spaces dry, safe and useable.

grade 1


Example uses of Grade 1 environments are listed within BS8102 as ‘Car parking; plant rooms (excluding electrical equipment) and workshops’.  The performance level is defined as: ‘Some seepage and damp areas tolerable, dependent on the intended use, local drainage might be necessary to deal with seepage’.


In essence, a basic car park which suffers minimal water seepage may be viewed as compliant with Grade 1, where the degree of penetration is not detrimental to the intended usage.

One of the key aspects to understand in respect of Grade 1, is that it is the only grade which allows a degree of water penetration, whereas no water penetration is acceptable with Grades 2 & 3.

If you are considering waterproofing to achieve Grade 1 which most commonly relates to basement car parking, make sure that you consider store rooms, lift lobbies (plus associated plant rooms) and stairwells, because these will require higher grades and can be costly to remedy.

Many dwellings, particularly those of Victorian construction, comprise small to medium areas of Grade 1 storage space.  If you are looking to convert to achieve liveable space, you will need to consult a waterproofing design specialist to enhance your existing waterproofing arrangement to a Grade 3.


grade 2


BS8102 provides examples for Grade 2 of ‘Plant rooms and workshops (requiring a drier environment than Grade 1)’.  The performance level is defined as: ‘No water penetration acceptable, damp areas tolerable; ventilation might be required’.


You may well ask how damp areas can be tolerable if no water penetration is acceptable?  This relates to airborne water vapour & condensation.  If we take the example of a basement car park store room, limited condensation-related dampness may not be an issue and it may be that the inclusion of ventilation (a mechanism for reducing condensation) as referred to in the standard, is enough to ensure that the space is as dry as it needs to be.

In such basic spaces, you would not ordinarily consider the inclusion of heating or dehumidification, which can be employed to prevent condensation, but a waterproofing design specialist will be able to advise you in all matters to ensure your basement space remains uncompromised and fit for purpose.

grade 3


BS8102 stipulates that ‘ventilated residential and commercial areas, including offices, restaurants etc.’ must meet a Grade 3 requirement.

This essentially means that ‘No water penetration is acceptable’, and that ‘dehumidification or air-conditioning may be necessary, appropriate to the intended use’.

Residential spaces require even more careful thought and meticulous planning; with fixtures, fittings, finishes and materials which may respond poorly to even limited dampness AND greater vapour production from domestic processes (cooking, washing, cleaning and breathing), it is necessary within Grade 3 to include suitable environmental controls so that condensation, and its harmful effects, can be eliminated at source.

how do i make sure my home is protected?


Whether you are overseeing the project yourself or have handed the reins over to your architect or structural engineer, you should make sure that a waterproofing design specialist has been engaged on your behalf.  Currently the only way to identify an individual who has put themselves through the rigours of study and qualification in this specialist field is to look for those who have attained the Certificated Surveyor in Structural Waterproofing (CSSW) qualification.

Your body is 60% water.  Your home shouldn’t be.  Contact Crownstone Group today on 0208 2265654 or visit www.crownstonegroup.co.uk to speak to one of our CSSWs about your project’s requirements.