Sprinklers in blocks of flats: what the rules require

The 11 metre rule

In England, new blocks of flats with a top storey above 11 metres must be fitted with sprinklers. The threshold was lowered to 11 metres in 2020, down from the previous 30 metres, through the Building Regulations guidance in Approved Document B.

Two things people get wrong about it:

It is a height threshold, not a storey count. It is measured to the floor level of the top storey above ground level, so a building’s storey count is a rough proxy at best.

It applies to new building work. It is not a retrofit duty on every existing block. Where existing blocks are being fitted with sprinklers, the driver is normally a fire risk assessment, a remediation programme, or an insurer, rather than that rule reaching backwards.

Which residential buildings this is about

Worth setting out, because “residential sprinklers” covers two quite different markets and only one of them has a professional buyer.

Buildings with a responsible person who is not a resident. Blocks of flats, purpose-built student accommodation, houses in multiple occupation, care homes, extra-care and supported housing. Somebody manages the common parts, the system is a communal fire safety measure, the cost goes through a service charge, and the duty under the Fire Safety Order sits with the freeholder or the managing agent. This is the work we do, and everything below is written for it.

Individual private houses. A domestic system in a single dwelling, installed for a homeowner. It is the same standard and a completely different trade: one householder, no common parts, no responsible person other than the occupier, and no maintenance contract. We do not do these, and if that is what you are looking for you want a domestic sprinkler installer rather than a commercial contractor. Saying so is cheaper for both of us than a survey that ends in a no.

The line is not the building type, it is whether somebody other than the occupier carries the duty for keeping the system working.

Why the standard is different

A residential sprinkler system is designed to BS 9251. A commercial one is designed to BS EN 12845. Using the wrong one is not a technicality.

BS EN 12845 assumes a commercial or industrial fire load: stored goods, racking, process risk, and a building that is protected primarily to limit loss. The hazard classification, the water supply duration and the density of discharge all follow from that.

BS 9251 assumes a home. The objective is to control a fire long enough for the people in that flat to get out, and for the fire not to spread beyond it. The design assumptions about occupancy, response and water supply are different, and so is the hardware.

A block of flats with a commercial spec applied to it is over-engineered in the wrong places and under-specified in others.

What a managing agent is signing up to

A sprinkler system in a residential block is a permanent maintenance commitment, and the practical burden is different from a warehouse.

• Access. Testing a residential system means getting into common parts, plant rooms and sometimes individual flats. Access is the single biggest scheduling problem in this sector.
• Heads in flats. The three defects found again and again are heads that have been painted, heads being used to hang things from, and heads obstructed by storage on top of wardrobes.
• The tank and the pump. Most residential systems have their own stored supply and pump set, which brings the pump routine with it.
• The record. For a block of flats the maintenance record is read by the fire risk assessor, the insurer, and increasingly by leaseholders asking what the service charge paid for.

Who is responsible for what, floor by floor

The question that causes the most argument in a block, and the answer is usually in the lease rather than in fire safety law.

Inside the flat. Heads, the pipework serving that dwelling, and access for testing. The leaseholder normally owns the fabric inside their demise, but the system is a communal fire safety measure, which is why almost every lease grants the freeholder or managing agent a right of access to maintain it.

Communal areas, tanks and pumps. The freeholder or managing agent, without exception in practice, and recovered through the service charge.

The duty under the Fire Safety Order sits with the responsible person for the common parts, which is the freeholder or the agent acting for them. That duty cannot be passed to leaseholders by a clause in a lease. The cost can be recovered; the responsibility cannot be moved.

Where it goes wrong is access. A system that cannot be tested inside a flat because the leaseholder will not let anybody in is still the responsible person’s problem, and the answer is the access provisions in the lease plus a written record of every attempt. Turning up twice and giving up is not a defence.

Refurbishments, and the damage nobody reports

Residential sprinkler pipework runs through ceilings and voids that get opened up for kitchen and bathroom work, and the people doing that work are rarely sprinkler contractors.

Three things happen repeatedly:

• Heads get painted. A painted head must be replaced, not cleaned. The same applies to a concealed head’s cover plate, which is a listed part of the assembly and is designed to drop away at a set temperature.
• Pipework gets moved or capped to make room, and the system is left modified with no drawing and no recommissioning.
• Ceilings are lowered, leaving a head above a new ceiling where it can do nothing at all.

None of it is malicious and none of it appears on a service report as a fault, because the system passes its test perfectly. It simply no longer protects the room it is in.

What to do about it: make sprinkler pipework a named item in the leaseholder alterations consent, and re-inspect after any works that opened a ceiling. It is one line in a licence to alter and it prevents the whole category.

The part that gets skipped

Commissioning documentation.

A residential system installed as part of a development is handed over with a design, a commissioning record and an as-fitted drawing. Those documents get lost between the developer, the first managing agent and the second one, and five years later nobody can say what the system was designed to do. It is the same file an insurer asks for, which is covered in what your insurer wants to see.

Whether a block was required to have sprinklers at all depends on when it was built and how tall it is: that is when a UK building legally needs sprinklers. For the servicing itself, that is sprinkler servicing.

If you have taken over a block and the sprinkler paperwork did not come with it, that is worth resolving before the next annual service rather than during it.