Statutory Inspections · Mandatory · Pre-Construction

RAMS — Basement Construction and Waterproofing

A specialist RAMS for basement construction combining deep excavation, temporary propping (BS 5975), groundwater control, confined space assessment, and chemical COSHH hazards from waterproofing materials (epoxies, isocyanates, bitumen). Covers BS 8102:2022 waterproofing design, environmental permitting for dewatering discharge, and pump failure contingency planning.

Last reviewed: 2 April 2026 — This guide reflects UK law as of this date. MHSWR 1999 / CDM 2015 / Confined Spaces Regs 1997 remains current with no amendments enacted as of 2 April 2026. Next scheduled review: 2 April 2027.

Legal basis	Management of Health and Safety at Work Regulations 1999 / CDM 2015 / Confined Spaces Regulations 1997
RAMS category	T12 Basement Construction & Waterproofing
Key risks	Deep excavation, temporary propping, groundwater ingress, confined space entry, COSHH for waterproofing materials
BS 5975	Code of practice for temporary works procedures — governs all temporary propping and shoring in basement construction
BS 8102:2022	Code of practice for protection of below-ground structures against water from the ground
Enforcing authority	Health and Safety Executive (HSE)

1. What It Covers

A RAMS for basement construction and waterproofing must address the combined hazards of deep excavation, temporary propping and shoring, groundwater control, confined space working, and the use of waterproofing materials that fall under COSHH. Basement construction is one of the most complex activities on a building project — it brings together geotechnical risk, structural risk, water management, and hazardous substance exposure in a single confined work environment. The consequences of inadequate planning range from ground collapse and flooding to toxic exposure and entrapment.

The RAMS must cover every phase from bulk excavation through to completion of the waterproofing envelope. It must address the temporary works design for propping and shoring (governed by BS 5975), the protection of adjacent structures from settlement, the groundwater control strategy (dewatering, cut-off walls, or pressure relief), confined space assessment under the Confined Spaces Regulations 1997, COSHH assessments for all waterproofing products, and the manual handling risks associated with working in restricted below-ground spaces. Hot works permits may also be required for torch-applied waterproofing membranes.

Confined space entry procedures may apply in basement areas

Basement areas can become confined spaces within the meaning of the Confined Spaces Regulations 1997 — particularly where ventilation is restricted, where waterproofing products generate solvent vapours, or where groundwater dewatering creates the risk of oxygen depletion or the accumulation of hazardous gases. The RAMS must include a confined space risk assessment for all below-ground working areas and define the entry procedures, atmospheric monitoring, ventilation, and rescue arrangements that will be applied where the assessment identifies a confined space.

“No person at work shall enter or carry out work in a confined space unless there have been prepared suitable and sufficient arrangements for the rescue of persons.”— Confined Spaces Regulations 1997 Regulation 5

2. Key Content

The basement construction and waterproofing RAMS must address each of the following areas in detail. The multi-hazard nature of basement work requires a comprehensive and coordinated approach.

Area	Detail required
Project description	Basement depth and footprint, number of basement levels, structural system (secant piles, contiguous piles, diaphragm walls, sheet piles), soil and groundwater conditions from the ground investigation report, proximity of adjacent structures
Deep excavation	Excavation sequence and method, maximum excavation depths, battered or vertical excavation faces, stability assessment for each excavation phase, monitoring regime (inclinometers, settlement markers), trigger levels and contingency actions
Temporary propping	Temporary works design in accordance with BS 5975, propping layout and sequence, appointed Temporary Works Coordinator (TWC) and Temporary Works Designer, design check category, prop installation and removal sequence, monitoring of prop loads, procedure for unexpected ground movement
Adjacent structure protection	Survey of all structures within the zone of influence, pre-condition survey, settlement monitoring (precise levelling, crack monitoring), trigger levels and action plan, party wall agreements where applicable, notification to adjacent owners
Groundwater control	Groundwater control strategy (dewatering by pumping, cut-off walls, grouting, or combination), dewatering pump capacity and standby arrangements, discharge route and consents (EA permit or sewer discharge consent), monitoring of water levels inside and outside the excavation, environmental impact on neighbouring water features
Confined space assessment	Assessment of all below-ground working areas against the Confined Spaces Regulations 1997, identification of areas that constitute confined spaces, entry procedures (permit to enter, atmospheric monitoring, ventilation, rescue arrangements), gas monitoring equipment (O2, LEL, CO, H2S), rescue team competence and availability
Waterproofing COSHH	COSHH assessments for all waterproofing materials — liquid-applied membranes, cementitious coatings, epoxy tanking, torch-applied sheet membranes, primers, adhesives. Safety data sheets, exposure controls, RPE and PPE requirements, ventilation for enclosed application areas, health surveillance where required
Manual handling	Assessment of manual handling risks in confined basement areas — restricted headroom, limited access for mechanical handling, heavy waterproofing rolls, working in awkward positions on walls and soffits. Controls including mechanical aids, team lifting, and task rotation
Hot works	Hot works permit required for torch-applied waterproofing membranes, fire risk assessment for below-ground hot works, fire watch arrangements, fire extinguisher provision, ventilation for fumes, restriction on hot works near combustible materials or insulation
Environmental	Contaminated land assessment and controls, disposal of excavated material (waste classification), prevention of silt and cement-laden runoff entering watercourses or drains, noise and vibration from excavation and propping activities
Emergency procedures	Site-specific emergency procedures for basement areas — flooding, ground collapse, gas accumulation, fire during hot works, operative incapacitation in confined space. Evacuation routes from all basement levels, emergency lighting, communication systems, rescue equipment location

3. Common Mistakes

Not appointing a Temporary Works Coordinator for basement propping

BS 5975 requires the appointment of a Temporary Works Coordinator (TWC) to manage all temporary works on the project, and a Temporary Works Designer to design the propping scheme. Basement propping is a critical temporary works activity — the props support the retaining walls against soil and water pressure, and their failure would result in catastrophic ground collapse. The TWC must be appointed before any temporary propping is designed, must approve the propping design, must issue a permit to load before props are loaded, and must control the sequence of prop installation and removal. Proceeding without a TWC is a serious breach of BS 5975 and CDM 2015.

Failing to assess basement areas as potential confined spaces

Basement areas can become confined spaces as defined by the Confined Spaces Regulations 1997, particularly during waterproofing when solvent vapours accumulate, during dewatering when ground gases are released, or in areas with restricted ventilation. Many basement RAMS fail to include a confined space assessment, assuming that because the space is part of a building it cannot be a confined space. The assessment must be carried out for every below-ground working area, considering the specific activities being undertaken and the ventilation conditions at the time of the work.

Inadequate groundwater contingency planning

Groundwater conditions can change rapidly and unexpectedly during basement construction. Pump failures, power outages, or unexpectedly high inflows can flood the excavation within hours. The RAMS must include a groundwater contingency plan that addresses pump failure, standby pumping capacity, emergency power supply, and the procedure for evacuating the basement if water levels rise beyond the trigger level. Relying on a single pump with no standby is a common and dangerous shortcoming.

No ventilation plan for waterproofing application in enclosed areas

Many waterproofing products — including liquid-applied membranes, epoxy coatings, and solvent-based primers — generate hazardous vapours that can accumulate rapidly in enclosed basement areas. The RAMS must include a ventilation plan that specifies mechanical ventilation equipment, air changes per hour, atmospheric monitoring during application, and the RPE to be worn. Applying solvent-based waterproofing products in an unventilated basement area has resulted in operative collapse and hospitalisation.

4. Frequently Asked Questions

What is BS 8102:2022?▾

BS 8102:2022 is the British Standard code of practice for protection of below-ground structures against water from the ground. It defines three types of waterproofing protection: Type A (barrier protection, applied externally or internally), Type B (structurally integral protection, where the concrete structure itself is designed to be watertight), and Type C (drained protection, using a cavity drain membrane system to manage water that penetrates the structure). Most basement waterproofing specifications require a combination of types — for example, Type A externally with a Type C cavity drain system internally as a secondary defence. BS 8102:2022 replaced the 2009 edition and includes updated guidance on risk assessment, design, and construction quality.

When does a basement area become a confined space under the regulations?▾

A confined space under the Confined Spaces Regulations 1997 is any place that is substantially (though not always entirely) enclosed, and where there is a reasonably foreseeable risk of serious injury from hazardous substances or conditions within the space or nearby. A basement area may become a confined space when: ventilation is restricted and hazardous vapours from waterproofing products can accumulate; groundwater dewatering releases ground gases such as methane or carbon dioxide; oxygen levels can be depleted by curing processes or displacement by other gases; or the area has restricted means of entry and exit that would impede rescue. The assessment must consider the conditions at the time of the work, not just the physical characteristics of the space.

Does the TWC need to be independent of the temporary works designer?▾

BS 5975 recommends that the TWC and the Temporary Works Designer are separate individuals to provide a check on the design process. However, on smaller projects, one person may fulfil both roles provided they have the competence to do so. For basement propping, which is a high-risk temporary works activity, it is strongly recommended that the TWC and Designer are separate individuals, and that the propping design is subject to a Category 3 design check (independent check by a party not involved in the original design). The principal contractor must satisfy themselves that the TWC appointment is appropriate for the complexity and risk of the temporary works.

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