How many toilets are required on a construction site?

Under CDM 2015 Schedule 2, a minimum of 1 toilet per 7 workers is required on construction sites. Toilets must be adequately ventilated and lit, with a suitable locking door for privacy. Chemical toilets are acceptable where mains drainage is not available. Toilets must be cleaned regularly and waste disposed of properly.

What welfare facilities are required under CDM 2015?

CDM 2015 Schedule 2 requires: toilets (1:7 workers), washing facilities with hot and cold water, drinking water, changing facilities, rest area with seating and means of heating food, drying room for wet clothing, and first aid facilities. All must be easily accessible, adequately ventilated and lit, and maintained in a clean condition.

How big should the site rest area be?

The rest area should provide approximately 1m² per person plus circulation space. For 20 workers, aim for at least 25-30m². The rest area must have seating with backs, a means of boiling water (kettle), a microwave or other means of heating food, and be heated in cold weather. It should be separate from work areas.

Is a drying room required on construction sites?

CDM 2015 requires facilities for drying wet clothing. In practice, this means a heated, ventilated drying room with hooks or racks for wet outer clothing and PPE. Allow approximately 0.5m² per worker. A portable heater and clothes rail in a dedicated space meets the minimum requirement for smaller sites.

How many first aiders are needed on a construction site?

For low-risk sites with 5-50 workers: at least 1 appointed person with first aid training. For sites with 50+ workers: 1 first aider per 50 workers. Construction is high-risk, so HSE recommends more first aiders than the minimum. All sites need at least 1 first aid kit compliant with BS 8599-1, restocked as items are used.

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Site Welfare Calculator

Calculate CDM welfare facilities for construction sites: toilets, washing stations, rest areas, drying rooms, first aid and drinking water based on worker numbers.

Peak Number of Workers

Maximum workers on site at any time

Include canteen/rest area

Required for all sites under CDM

Include drying room

Required for wet clothing storage

Toilet Hire Cost Each (optional)

Weekly hire cost per toilet unit

Welfare Unit Hire (optional)

Weekly hire for combined welfare unit

How We Calculate This

This calculator determines the minimum welfare facilities required under CDM 2015 Schedule 2 for construction sites, based on the peak number of workers.

The formula

Toilets = Peak workers ÷ 7 (rounded up)
Washing stations = Peak workers ÷ 7 (rounded up)
Rest area = Peak workers × 1 m²
First aiders = Peak workers ÷ 25 (rounded up, min 1)

For 30 workers: 5 toilets, 5 washing stations, 30m² rest area, 15m² drying room, 1 first aid kit, and 2 first aiders.

CDM welfare requirements

Toilets and washing facilities: clean, maintained, 1:7 ratio
Rest area: heated, seating, food preparation
Drinking water: clearly marked, accessible
Changing/drying: separate from work areas, heated

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.