How Many Welfare Units Do You Need Per Site?
UK guidance (BS 6465-1:2006, referenced by HSE) recommends one toilet per 7 workers on a standard 40-hour week, where units are serviced weekly. There’s no single fixed legal number, the actual legal test under CDM 2015 is “suitable and sufficient” for your site, but the 1:7 ratio is the practical benchmark most site managers and HSE inspectors work from.
If you’re planning welfare provision for a construction site, the number of toilets you need depends on your workforce size, shift pattern, and how often units are serviced. Below is a practical breakdown you can use to plan, along with what the law actually requires.
The legal requirement, in plain terms
The Construction (Design and Management) Regulations 2015 (Schedule 2) require “suitable and sufficient” sanitary conveniences at readily accessible locations. It doesn’t give you a fixed number. Instead, HSE guidance (CIS59) and the British Standard BS 6465-1:2006 fill that gap with a practical ratio: one toilet for every 7 people working a 40-hour week, assuming weekly servicing.
HSE also expects toilets to be reasonably close to where people are working, guidance points to around 150 metres, or roughly a 2-minute walk, so workers aren’t losing significant time travelling to facilities.
Rough guide by workforce size
Using the 1:7 ratio as a starting point, here’s roughly what that looks like in practice (always round up):
| Workers on site | Toilets needed (1:7 ratio) |
|---|---|
| 1–7 | 1 |
| 8–14 | 2 |
| 15–21 | 3 |
| 22–28 | 4 |
| 29–35 | 5 |
| 50 | 8 |
| 100 | 15 |
When you’ll need more than the ratio suggests
- Multiple shifts: if your site runs more than one shift, facilities need to cover peak concurrent numbers, not just total headcount across the day.
- Mixed-gender workforce: separate facilities are generally expected, or lockable, single-occupancy unisex units where separate provision isn’t practical.
- Larger or spread-out sites: if workers can’t reach a toilet within roughly 150m or 2 minutes, you may need satellite units in additional locations rather than just adding to one bank of toilets.
- Visitors and subcontractors: if your site regularly has additional people on top of your core team, they need to be factored into the count too.
- Less frequent servicing: the 1:7 ratio assumes weekly emptying. If units are serviced less often, you’ll need more units to keep pace with usage.
Frequently asked questions
How many toilets does a 10-person construction site need?
Based on the 1:7 ratio, a 10-person site needs 2 toilets (10 ÷ 7 = 1.43, rounded up). This assumes a standard 40-hour week and weekly servicing.
Is there a legal minimum number of toilets on a UK construction site?
Not a fixed number in law. CDM 2015 requires “suitable and sufficient” facilities, and HSE inspectors typically use the BS 6465-1:2006 ratio of 1 toilet per 7 workers as the practical benchmark when assessing compliance.
Do construction site toilets need to be separated by gender?
Generally yes, where practical. Where separate facilities aren’t possible, lockable, single-occupancy unisex units with both a toilet and a sink are the accepted alternative.
How often do portable toilets need to be serviced on a construction site?
The 1:7 ratio assumes weekly servicing. If you can’t service units that often, you’ll typically need to increase the number of units on site to compensate.
What happens if a construction site doesn’t have enough toilets?
Insufficient welfare provision is a breach of CDM 2015 and can result in HSE enforcement action, including improvement notices or fines. Inspectors commonly cite queuing or overuse as evidence of non-compliance.
Need welfare units sorted for your site?
Tell us your worker count and we’ll work out exactly what you need, no guesswork.
Get a quote