QR site sign-in vs turnstiles: site access control for principal contractors

As principal contractor, you are responsible for knowing who is on your site, that they were inducted before they started, and that they are qualified to be there. You also have to be able to prove it after the fact. There are broadly three ways to control site access in UK construction, and they are not equal on cost, speed, or the quality of the evidence they leave behind.

The paper signing-in book

A signing-in sheet in the site cabin is the default on most small and medium sites. It is cheap and needs no setup. The problem is that it does almost nothing beyond recording a name and a scrawled time.

A paper book does not enforce an induction, so there is nothing stopping someone signing in who has never been told the site rules. It does not check a CSCS card or any other credential. It is frequently illegible, often filled in retrospectively, and a single coffee-stained page can be lost. When a client, an auditor or the HSE asks who was on site on a specific day three weeks ago, a paper book is a reconstruction exercise, not an answer.

For a single contractor on a small domestic job, a light-touch record may be proportionate. For a principal contractor coordinating several subcontractor companies, it is the thing that fails the audit.

Turnstiles and biometric hardware

At the other end of the scale, large principal-contractor sites often install turnstiles with card or biometric readers. These do one thing very well: they physically control a perimeter. If you genuinely need to stop unauthorised people walking onto a secured Tier-1 site, hardware access control is the tool for it.

The trade-offs are cost and flexibility. Turnstiles are capital expenditure. Each site needs the gates, the readers, and an install, plus ongoing maintenance. On a fast-moving fit-out, a short programme, or a site where the layout changes week to week, that cost and delay is hard to justify. Hardware also tells you that a valid card was presented at the gate — it does not, on its own, generate your Construction Phase Plan, your RAMS, or your COSHH assessments. The compliance paperwork still has to come from somewhere.

QR sign-in from the worker's phone

The third option sits between the two. A permanent QR code at the site entrance lets every worker, visitor and subcontractor sign in and out from their own phone — no app to install, no clipboard, and no hardware to buy.

Because the sign-in runs in software, it can do things a paper book and a turnstile cannot:

• The digital site induction becomes a hard gate. No one is checked in until it is complete and acknowledged, and the timestamp is recorded automatically.
• CSCS and other credentials are captured at sign-in, reviewed, and flagged before they expire.
• A new subcontractor company self-joins behind the same QR and onboards its own workers, without you keying anything in.
• You get a live people-on-site view for fire roll-call and a full attendance history per site.

A new site goes live as soon as you print its QR, so there is no per-site capex or install. The obvious limit is that a QR on a phone is not a physical barrier — it does not lock a gate the way a turnstile does. For most principal contractors who need evidence and oversight rather than a secured perimeter, that is an acceptable trade.

What CDM 2015 actually requires

It helps to separate the duty from the method. CDM 2015 does not tell you to buy turnstiles or to use a particular app. Regulation 13 puts the site induction on the principal contractor, you are expected to know who is on site for emergency roll-call, you must satisfy yourself that workers are competent, and you must keep records that stand up to scrutiny.

The signing-in book, the turnstile and the QR are all just methods of meeting those duties. The question is which method actually produces the evidence — an induction that was enforced, a credential that was checked, an attendance record that was captured as it happened — rather than a record you have to defend or rebuild later.

Which approach fits your sites

• A single domestic job with one contractor: a proportionate, light-touch record is usually enough.
• Several live sites with subcontractors, where you need evidence and oversight but not a secured perimeter: QR sign-in gives you induction gating, CSCS checks, attendance and audit exports without hardware on every site.
• A high-security site that must physically control who passes the gate: turnstiles or biometric access control — but you will still need a separate layer to generate and evidence the CDM paperwork.

How The Site Book handles it

Site Control is our per-site tier for principal contractors running live sites. It runs the whole chain from one permanent entrance QR: contractor self-join, induction gating before check-in, CSCS capture with expiry alerts, live people-on-site and attendance history, RFIs tied to document-review evidence, and audit-grade exports on demand. There is no turnstile to buy and no hardware to install, and it generates the full UK CDM pack — RAMS, Construction Phase Plans, COSHH and inductions — in the same tool. It is priced per active site with unlimited workers, from £675 per site per month. If you are running more than one live site, that is the layer worth looking at.