Who carries out intrusive fire stopping investigations?

What intrusive means

A non-intrusive survey records what can be seen without opening anything up: risers, plant rooms and ceiling tiles that lift out. An intrusive investigation goes behind the finish. The surveyor cuts or removes a small area of ceiling, boxing, plasterboard or cladding at chosen points to see whether the fire stopping, cavity barriers and fire-resisting lining are there and are right.

Fire stopping is mostly hidden, so a visual survey finds the openings in plant rooms and risers but cannot see what sits above a sealed ceiling or behind a boxed-in service. Where a fire risk assessment says compartmentation could only be checked where it was visible, an intrusive investigation is the next step.

When you need one

• A fire risk assessment records that compartmentation was not fully checked
• The building has had cabling, pipework or M&E work through compartment walls and nobody recorded the fire stopping
• A change of use, such as offices to flats, or a house to an HMO
• You are buying, refinancing or insuring a building and are asked for evidence of fire separation
• A higher-risk building needs evidence for its safety case and the golden thread
• A non-intrusive survey found poor work and you need to know how far it goes

The compartmentation survey page covers the same work from the side of the whole building, and when you need a compartmentation survey sets out the triggers.

What the surveyor does

1. Drawings first. We ask for the fire strategy and floor plans. Without them, we mark a floor plan up on site and say so in the report. 2. Choose the opening points. Opening up everything is neither practical nor necessary. The surveyor picks a sample from the drawings and the visible findings, including the places most likely to be wrong: above corridor ceilings, at riser floors, where walls meet the slab and behind boxing. 3. Check for asbestos first. In an older building, the asbestos register or survey is checked before anything is cut or lifted. 4. Open up, look, photograph. Each opening gets a number, a plan reference, a photo of what is behind it and a photo of the wider area, with a note of the wall or floor and what passes through. 5. Widen the sample if the first openings show poor work. If the first points show missing or poor fire stopping, we say so and propose more, and agree them with you first. 6. Make good. Openings are closed and finished. In an occupied building we agree access, dust and noise arrangements and who tells residents or tenants. 7. Report. A defect schedule with photos and plan references, ranked by risk, that says what is needed at each location.

Who should carry one out

There is no single licence. These are the questions that separate a competent surveyor from a quick look:

• Does the surveyor understand tested fire stopping systems, not just that a gap exists?
• Can they show the same kind of report from a previous job?
• Do they record each opening with a photo, a number and a plan reference?
• Is the work carried out or backed by third-party certification for passive fire protection?
• Is the survey separate from the repair, so you can get a second price for the sealing?

You are free to take our schedule to anyone else for pricing. If the same firm finds the problems and prices the repair, getting a second price on the same schedule is the simplest check.

What an intrusive investigation costs

It is priced per job. The number of floors and cores, how many compartment areas there are, the amount of opening up and making good, and whether the building is occupied all change the time on site. We price from your drawings or photos. We do not publish a figure because the same floor area can need very different amounts of opening up.

What happens afterwards

The schedule gives you the list of locations and what each needs. The survey side is covered in fire stopping survey, and choosing a fire stopping contractor lists what to ask for the sealing. Under the Fire Safety Order the responsible person has to keep fire protection in efficient working order and good repair (article 17), so the schedule is also your record of what you found and what you did about it.

Sources

• Regulatory Reform (Fire Safety) Order 2005, article 17 (legislation.gov.uk)