BS 8102:2022
Key changes from BS 8102:2009.
More than a renaming exercise. The 2022 standard restructures the grades, strengthens combined-protection expectations, formalises the role of the competent designer, and tightens the documentation chain the design team is expected to produce.
Why it matters
The 2022 standard is what you'll be judged against.
The 2022 revision of BS 8102 is more than a renaming exercise. It restructures how performance grades are described, strengthens the expectation for risk-led combined protection, formalises the role of the competent waterproofing designer, and tightens the documentation chain that the design team is expected to produce.
For architects, structural engineers, project managers, asset holders and Building Safety Act duty holders, the practical effect is that the 2022 standard is likely to be used as a key benchmark by courts, adjudicators and insurers when assessing whether a below-ground waterproofing failure could reasonably have been prevented.
Change 1
A broader title, and a broader scope.
The 2009 edition was the code of practice for protection of below ground structures against water from the ground. The 2022 title drops that qualifier: protection of below ground structures against water ingress. The scope wording changed to match, from "the entry of water from surrounding ground" to "the entry of water from external sources" into structures partly or wholly below ground.
Clause 6 makes the consequence explicit: the water resisting design should take account of surface water, including inundation during storm events, and flooding from pluvial, fluvial, groundwater, coastal or drainage sources. The technical guidance also grew by roughly a third, from around 15,000 words to around 20,000.
The practical effect: waterproofing designers no longer have the protection of the narrower 2009 wording. Any ingress into a below-ground structure is likely to be read as within the standard's territory, and flood risk is now the designer's business.
Change 2
Grade structure, and what drives the grade.
BS 8102:2009 specified three grades: Grade 1, where some seepage was tolerable; Grade 2, where no liquid water was acceptable but water vapour was tolerable; and Grade 3, which required a dry environment.
BS 8102:2022 splits the old Grade 1 into two distinct grades: Grade 1a, where some seepage and damp areas are tolerable, and Grade 1b, where no seepage is acceptable but damp areas may be tolerable. This produces four grades in total.
Two quieter revisions matter as much as the split. The worked examples were removed from Table 2, and Clause 6.2.4 notes that the internal finishes might dictate the required grade, so grade selection is now unambiguously specific to the intended use of each space rather than read off a list. And "damp area" was redefined, from an area that might leave a light film of moisture on the hand to simply "an area which is slightly wet but no seepage", a looser and arguably wetter definition that invites subjectivity about how damp damp can be.
The practical effect: greater precision at the bottom of the scale, and a grade decision that must be made, justified and recorded per space, by someone competent to make it.
Change 3
Combined protection at Grade 3.
BS 8102:2009 permitted Grade 3 to be delivered by a single waterproofing system in some circumstances. BS 8102:2022 places greater emphasis on combined protection where the risk profile, intended use, consequence of failure and maintainability requirements justify it.
This commonly means using two of the three waterproofing types in combination: Type A barrier protection, Type B structurally integral protection, and Type C drained protection. In higher-risk situations, all three types may need to be considered.
Clause 6.2.3 also adds a pointed requirement: combined systems should have different performance characteristics. Doubling up two systems that fail the same way is not combined protection.
The practical effect is that a Grade 3 specification using a single system carries a higher technical risk and a higher dispute risk under the 2022 standard, unless the design team can clearly justify the approach through risk assessment, buildability, inspection access, maintenance strategy and consequence of failure. Some previously acceptable combinations no longer qualify.
Change 4
Formal role of the competent waterproofing designer.
BS 8102:2009 said a waterproofing specialist should be included as part of the design team. BS 8102:2022 says one should be appointed, with guidance on when, and on Contractor's Designed Portion arrangements. The language of appointment infers a contract: more responsibility for the specialist, and more influence within the design team to go with it.
The expectation is that a competent waterproofing designer is appointed as early as possible, typically by RIBA Stage 2 or equivalent. The designer should be suitably qualified and experienced in below-ground waterproofing design and should contribute to the design philosophy, risk assessment and performance specification.
The CSSW qualification, Certificated Surveyor in Structural Waterproofing, is a recognised UK credential for waterproofing designers. We see asset holders and Tier 1 contractors increasingly asking for CSSW credentials in PQQs and pre-construction information for below-ground projects.
A higher standard of qualification for a structural waterproofing designer is the Waterproofing Design Specialist (WDS). This is a peer reviewed Register held by the Property Care Association. The clearest evidence of competence within the structural waterproofing design discipline is membership of the WDS register and it is therefore highly recommended on major complex schemes.
Change 5
Site evaluation and the risk assessment got teeth.
Clause 5 on site evaluation is substantially more comprehensive and more onerous in the 2022 edition. The risk assessment is wider, taking in considerations such as SuDS, and water pressure should be considered to the full height of the retained structure, not merely today's water table. Ground conditions change over a building's design life; designing to the current borehole reading is designing to a snapshot.
For existing structures, Clause 5.2 now calls for a comprehensive inspection, with itemised requirements running from (a) through to (t), and buildings of historic significance are addressed in their own right.
The practical effect: a responsible waterproofing specialist following BS 8102:2022 will often require a more detailed site investigation than the client had planned to procure. That conversation is better had at Stage 2 than in a dispute.
Change 6
Buried decks and podium decks: an entirely new section.
Clause 6.5 on buried decks did not exist in 2009. The 2022 guidance is strong on achieving falls and drainage, expects reinforced concrete substrates and fully bonded systems, and notes permanent leak detection for warm roof build-ups. Podium decks, buried roofs and similar structures are now squarely inside the standard's scope.
The practical effect: podium and buried-deck waterproofing is no longer a gap between codes. CLW's podium deck waterproofing guide covers the design consequences in full.
Change 7
Construction stage, materials and beyond.
Design responsibility no longer stops at drawing issue. The 2022 edition calls for a Water Management Plan considering water entry during construction (Clause 7.1), adds a new section on protecting installed waterproofing through planning and sequencing (Clause 7.5), and advises that movement joints below ground should generally be avoided, with additional quality assurance where they cannot be (Clause 8.1.5).
On materials: sandwich waterproofing has been removed from the guidance and barrier membranes are expected to be fully bonded; designers should verify full compatibility between pre- and post-applied membranes; Type B concrete now carries clear reference to BS EN 1992-3 crack-width requirements, explained in the tightness-class section of our grades hub; and the Type C guidance is more extensive, including new content on multi-level systems and on discharge and flood protection, which connects to maintainable drainage under BS 8102.
The practical effect: the standard now follows the waterproofing from design intent through construction, commissioning and maintenance. So does the liability.
FAQ
BS 8102:2009 vs 2022, what people ask.
What changed between BS 8102:2009 and BS 8102:2022? read
Seven substantial shifts: the scope broadened from "water from the ground" to water ingress from external sources, including surface water and flooding; the old Grade 1 split into Grades 1a and 1b, with the Table 2 examples removed so intended use and finishes drive the grade; combined protection expectations strengthened, with combined systems expected to have different performance characteristics; the competent waterproofing designer is now appointed, not merely included; site evaluation and the risk assessment became substantially more onerous; buried decks and podium decks gained an entirely new section, Clause 6.5; and construction-stage duties expanded, from water management plans to protecting installed waterproofing.
Is BS 8102:2009 still valid? read
No. BS 8102:2022 superseded the 2009 edition when it was published in March 2022. Designs still quoting the 2009 grades or relying on its narrower "water from the ground" scope are referencing a withdrawn document, which is a recurring finding in design reviews and disputes.
Does BS 8102:2022 cover flooding and surface water? read
Yes, and this is one of the most consequential changes. The 2022 scope covers water ingress from external sources, and Clause 6 states that protection should take account of surface water, including inundation during storm events, and flooding from pluvial, fluvial, groundwater, coastal or drainage sources. Waterproofing designers no longer have the protection of the 2009 edition’s narrower "water from the ground" wording.
Do podium decks and buried roofs fall under BS 8102? read
Under the 2022 edition, explicitly yes. Clause 6.5 is an entirely new section on buried decks, with strong guidance on achieving falls and drainage, and a note on permanent leak detection for warm roof build-ups. The 2009 edition did not address them directly.
Is BS 8102:2022 retrospective? read
Not automatically. It applies to new designs and may be adopted by agreement on existing or ongoing projects. For existing structures it is commonly used as the current best-practice benchmark when assessing risk, performance and remedial options.
Need a competent waterproofing designer on the appointment?
CLW holds three registered Waterproofing Design Specialists. Ben Hickman sat on the BS 8102:2022 committee.
Contact CLWGet a defensible Grade recommendation in 3 exchanges.
The Waterproofing Wisdom Agent is CLW's specialist AI consultant. Tell it the scheme; it'll reason from BS 8102:2022 toward the right Grade for each space.
Try the Waterproofing Wisdom Agent