Basement Waterproofing RAMS: A Complete UK Guide

Table of Contents

• Why Basement Waterproofing RAMS Matter
• Types of Basement Waterproofing Covered
• Key Hazards in Basement Waterproofing
• Confined Space Controls
• COSHH Assessments for Waterproofing Products
• What Your Waterproofing RAMS Must Include
• Frequently Asked Questions
• Next Steps

Why Basement Waterproofing RAMS Matter

Basement and below-ground waterproofing works combine several of construction's most significant risk categories: confined space working, exposure to chemical products (many of which are highly toxic or flammable), working at height from ladders and low-level platforms in restricted spaces, and manual handling in tight conditions. Pair these with the inherent complexity of the waterproofing systems themselves and the consequences of getting either the safety management or the technical specification wrong, and you have a compelling case for thorough, well-written RAMS.

Under CDM 2015, waterproofing contractors must produce RAMS before work begins. This guide covers the key risks and what your documents must include. For a general introduction to RAMS in UK construction, see our RAMS guide for UK construction.

Types of Basement Waterproofing Covered

UK basement waterproofing is classified under BS 8102:2022 (Protection of Below Ground Structures Against Water from the Ground) into three types:

• Type A — Barrier protection — A waterproof barrier applied to the structure (externally or internally). Includes: bituminous tanking (hot or cold applied), cementitious render coatings (crystalline or hydraulic), crystalline capillary systems, and sheet membranes. Applied to the internal face of the structure when external application is not accessible.
• Type B — Structurally integral protection — The concrete structure itself is made waterproof by mix design (waterproof concrete) and crack control. Usually a permanent works solution designed by the structural engineer.
• Type C — Drained protection (cavity drain) — A studded dimple membrane is installed against the internal face of the structure, with a drainage system and sump pump collecting and removing any water that penetrates. The most common retrofit solution for existing basements.

Each type has different COSHH implications, different confined space considerations, and different application sequences. Your RAMS must reflect the specific type being installed.

Key Hazards in Basement Waterproofing

• Confined space — Many below-ground structures meet the definition of a confined space under the Confined Spaces Regulations 1997: restricted entry and exit, limited ventilation, and a reasonably foreseeable risk from fumes, oxygen depletion, or flooding. This is addressed in detail below.
• Chemical exposure — Waterproofing products range from water-based cementitious systems (low hazard) to solvent-based bituminous products and two-component polyurethane or epoxy coatings (high hazard). COSHH assessments are required for every product used.
• Fire and explosion — Solvent-based waterproofing products generate flammable vapours. In a poorly ventilated basement, these vapours can reach explosive concentrations. A hot works permit is required if any ignition sources (tools, equipment, open flames) will be present.
• Manual handling — Heavy materials (20kg bags of cementitious mortar, rolls of membrane) must be carried down stairs or through manholes into the working area. Manual handling assessments for basement ingress routes must be completed.
• Working at height — Work on walls and ceilings of basements often requires stepladders or low-level platforms. The limited headroom in many basements restricts the options for access equipment.
• Moisture and electrical hazards — Working in damp or wet below-ground environments with power tools and temporary lighting creates electrocution risks. RCD protection for all power supplies is mandatory.
• Poor illumination — Basements often have limited or no natural light. Adequate temporary lighting must be provided and documented in your RAMS.

Confined Space Controls

Before any work begins in a basement or below-ground space, a confined space assessment must be completed. This assessment must determine whether the space meets the definition in the Confined Spaces Regulations 1997 — specifically, whether there is a reasonably foreseeable risk from:

• Loss of consciousness due to oxygen depletion or enrichment
• Loss of consciousness or incapacity due to gas, fume, vapour, or liquid
• Drowning (rapid ingress of liquid)
• Asphyxiation (ingress of free-flowing solid)
• Fire or explosion

For basement waterproofing, solvent-based products create an automatic risk of flammable vapour accumulation, making most basement working areas confined spaces when such products are used. Even when water-based products are used, the below-grade nature of the space and limited ventilation may still meet the definition.

If the space is a confined space, the following controls apply:

• A written confined space entry permit must be completed before each entry.
• Atmospheric testing must be carried out before entry and continuously during work: oxygen level (between 19.5% and 23.5% is the safe range), flammable gas (below 10% of Lower Explosive Limit), and carbon monoxide and hydrogen sulphide (below workplace exposure limits).
• A non-entry rescue system must be in place: a trained rescue team (minimum 2 persons, ideally 3), with rescue equipment (tripod, winch, and harness) immediately available at the entry point. Entry rescue (entering the space to retrieve an incapacitated person) is extremely hazardous and should only be a last resort.
• A communication system between persons inside and outside the space must be maintained throughout.
• All persons involved in confined space working must be trained under the Confined Spaces Regulations.

COSHH Assessments for Waterproofing Products

A separate COSHH assessment must be completed for every waterproofing product used, based on the manufacturer's Safety Data Sheet (SDS). Key product categories and their hazard profile are:

• Solvent-based bituminous tanking — Contains hydrocarbons (typically Solvent Naphtha or similar). Highly flammable (Flash Point typically <23°C). Harmful by inhalation. Workplace Exposure Limit for Naphtha is 350 mg/m³ (8-hour TWA). Requires forced ventilation to maintain levels below WEL and below explosive limits, respiratory protection (A1P2 cartridge half-mask as minimum), and elimination of all ignition sources.
• Cementitious coatings and renders — Contain Portland cement (alkaline, pH 12-13). Risk of cement dermatitis and chemical burns. Controls: waterproof gloves, eye protection, knee pads if applying kneeling, washing facilities.
• Two-component polyurethane coatings — Component B contains isocyanates (sensitisers — can cause occupational asthma). Must not be used by anyone without appropriate respiratory protection and training. Supplied air or P3 filter masks required for spray application. Once sensitised, a worker cannot return to isocyanate exposure environments.
• Crystalline waterproofing systems — Generally lower hazard (cement-based). The primary risk is the same as for cementitious coatings.

All COSHH assessments must be reviewed before use of any product on a different site or when a product is changed for an equivalent from a different manufacturer.

What Your Waterproofing RAMS Must Include

• Reference to BS 8102:2022 and the specific waterproofing type being installed
• Confined space assessment and, if applicable, confined space entry procedure and rescue plan
• COSHH assessments for all waterproofing products
• Ventilation arrangements (forced ventilation where required)
• Fire and explosion controls (elimination of ignition sources, fire extinguisher provision, hot works permit if applicable)
• Electrical safety (RCD protection, IP-rated luminaires in wet conditions)
• Manual handling assessment for material delivery to the working area
• Access equipment for walls and ceiling work
• Lighting provision
• Emergency procedure for fumes or fire in the confined space
• Competency requirements (confined space training certificates, manufacturer's product training if applicable)

Generate a complete waterproofing RAMS using the RAMS AI basement waterproofing template.

Frequently Asked Questions

Does every basement job require a confined space permit?

Not necessarily — but it requires a confined space assessment to determine whether a permit is needed. If no hazardous products (solvents, bitumen, etc.) are being used and the space has adequate natural ventilation, it may not meet the definition of a confined space. If solvent-based products are being used in any below-grade space with limited ventilation, it almost certainly does. Err on the side of caution: if in doubt, treat it as a confined space.

What qualifications are required for waterproofing operatives?

Most specialist waterproofing manufacturers offer product training and certification for their application systems (e.g., CSCS cards plus manufacturer certification for approved applicators). For confined space work, all entrants must hold a recognised confined space training certificate (e.g., BOHS or CISRS recognised). For isocyanate products, specific isocyanate awareness training is required for all operatives. Check your principal contractor's requirements — many now specify Level 2 or Level 3 NVQ in Waterproofing as a minimum qualification for specialist basement waterproofing works.

How do I handle solvent-based products in very deep basements with poor access?

If the access for forced ventilation equipment is severely limited (e.g., single manhole entry), you should reconsider whether solvent-based products are appropriate. BS 8102 allows for Type A waterproofing using water-based cementitious or crystalline systems in many applications. Specify water-based alternatives where the confined space risk from solvents cannot be adequately controlled. This is an application of the COSHH hierarchy of control: substitution of a less hazardous product before relying on engineering controls and PPE.

Next Steps

Browse all trade RAMS templates on the RAMS AI trade hub — covering 22 specialist construction trades.

Basement waterproofing RAMS require careful integration of confined space management, COSHH compliance, and product-specific application requirements. RAMS AI provides a comprehensive template that brings all of these elements together, ready to be tailored to your specific project and products.