Builderswork and fire stopping

The holes the services need — formed by design where possible, sealed with tested systems, proven with photographs.

Builderswork and fire stopping — MEP First Fix

Last updated 2026-07-28 by the BuildPedia Editorial Team.

What is Builderswork and fire stopping?

Builderswork is the unglamorous scope that lets everything else happen: the holes, sleeves, chases, box-outs and cast-in items that carry services through the structure, and the lintels over openings formed for services runs. Done well, it is designed — a builderswork drawing agreed with the frame designer, sleeves and blockouts cast into the slabs pour by pour, holes formed in walls as they are built. Done badly, it is a man with a core drill improvising near a beam, and every improvised hole through the structure without approval is a structural non-conformance waiting for a signature it will not get.

Where a penetration crosses a compartment wall or floor, the hole also destroyed a piece of the building's fire resistance, and that resistance is restored with a tested, certificated seal — labelled, registered and photographed. The headline matters here; the detail does not need repeating. System selection, cavity barriers, linear gap seals, certification and remediation are covered in full in the Firestopping and Passive Fire Protection guide — read that alongside this one.

Get the builderswork right and the first-fix programme accelerates: no drilling schedule behind the concrete gang, no surprise reinforcement in the way of a riser, no re-cut openings when the services drawings land. Get it wrong and the cost lands twice — structural sign-off for the hole itself, then the fire-stopping remediation behind it. The penetration register and photographic record opened at first fix become the golden-thread evidence the building keeps for the rest of its life.

How does Builderswork and fire stopping work, step by step?

Step 1: Issue the builderswork drawing before the structure

Issue the builderswork drawing before the structure — Builderswork and fire stopping, step 1

Holes, sleeves and cast-in items are coordinated with the frame design and scheduled pour by pour, wall by wall. Positions near beams, columns and slabs are agreed with the structural engineer on paper — never negotiated with a core drill in hand.

Step 2: Form or core the penetrations

Form or core the penetrations — Builderswork and fire stopping, step 2

Cast-in sleeves and formed holes are set as the structure proceeds. Where drilling is unavoidable, positions are scanned for reinforcement, approved by the engineer, and cored cleanly. A hole through a beam without sign-off stops the job, not just the trade.

Step 3: Sleeve and fire-stop as services pass

Sleeve and fire-stop as services pass — Builderswork and fire stopping, step 3

As each service passes a compartment line, the penetration is sealed with the tested system certificated for that service type, size and substrate — batt, collar, pillow or sealant as the detail demands, installed to the letter of its certification.

Step 4: Label, register and photograph every seal

Label, register and photograph every seal — Builderswork and fire stopping, step 4

Each completed seal gets a printed label — installer, date, system reference — and is logged on the penetration register with before and after photographs. Services added later are stopped and registered as they go: a re-routed cable through an old seal is a new penetration. The system selection and certification detail behind each seal is covered in the Firestopping and Passive Fire Protection guide.

Step 5: Inspect and close out

Inspect and close out — Builderswork and fire stopping, step 5

Sampled inspections walk the register against the physical seals; non-conformances are re-sealed and re-recorded. A joint walk-down with the boarding trade checks every compartment line before closure — the last chance anyone gets to see it.

What are the benefits of Builderswork and fire stopping?

What are the limitations of Builderswork and fire stopping?

What is Builderswork and fire stopping best suited for?

What plant does Builderswork and fire stopping need?

How is Builderswork and fire stopping quality-checked?

Related processes