Professional indemnity insurance for building services consultants

Who this covers

Building services is a broad description. In practice it takes in mechanical and electrical design consultancies, MEP and MEPH engineers, public health and drainage designers, HVAC specialists, energy modellers and sustainability consultants, BREEAM and net-zero advisers, commissioning managers, and specialist contractors carrying a design portion. Many firms sit in more than one of those categories, and the underwriting question is always the split of fee income across them — not the description on the letterhead.

Closely related work is covered elsewhere: consulting engineers for the contract-led view, engineers’ PI as a product page, and principal designer insurance where a dutyholder role is being taken.

Where the claims come from

Design that does not perform. Systems that do not deliver the specified capacity, temperature, air quality or acoustic outcome. The loss is usually the cost of remediation plus the consequences of a delayed handover, and the amounts bear no relation to the design fee.

Coordination and interface failures. Services clashing with structure or architecture, insufficient plant space, riser and builder’s work omissions discovered on site. These generate variation and delay claims that get passed down.

The modelled-versus-measured gap. Energy modelling, thermal performance and carbon assessments produce numbers that clients increasingly rely on commercially. When the building in use does not match the model, the consultant is the obvious defendant — and the claim is often framed as a warranty about outcome rather than a criticism of the method.

Fire safety interfaces. Ductwork penetrations, fire dampers, smoke control, sprinkler and suppression design, and the compartmentation implications of services routes. Since the Building Safety Act 2022 these have become the highest-scrutiny part of a services engineer’s scope.

Commissioning and handover. Systems signed off as commissioned that were not, incomplete O&M information, and controls strategies that were never properly demonstrated.

The contract problem: skill and care versus fitness for purpose

A professional indemnity policy is built to respond to a breach of the duty to exercise reasonable skill and care. Most wordings either exclude, or do not cover, liability assumed under a contract that goes further — a guarantee, a warranty of a result, or a fitness-for-purpose obligation. Building services contracts are unusually prone to this, because clients naturally express what they want as an outcome: a temperature, an energy rating, a capacity, a completion date.

The practical consequence is that a firm can sign an appointment that creates a liability its insurance was never designed to meet. The controls are unglamorous and effective: review appointments and collateral warranties before signature, resist absolute obligations, cap liability where the client will accept it, and use net contribution clauses. Our page on collateral warranties and your PI programme deals with the downstream documents, which are frequently where the worst wording appears.

The Building Safety Act and higher-risk buildings

The 2022 Act changed both the duties and the exposure. It introduced dutyholder roles across the design and construction process with competence requirements attached, created a gateway regime for higher-risk buildings, and extended the limitation periods for claims under section 1 of the Defective Premises Act 1972. For a services consultant the immediate effects are that the scope of a role must be documented far more carefully, that competence has to be evidenced rather than asserted, and that historic residential work now sits within a longer tail than the profession was underwritten for.

See M&E design risk under the Building Safety Act for the discipline-specific detail, section 135 and the limitation change, and the Act and PI generally.

Fire safety and cladding exclusions

Since 2017 the PI market has applied fire safety and cladding exclusions widely, and building services firms are caught by them more often than they expect — not because they design facades, but because ductwork, penetrations, dampers and smoke control sit inside the fire strategy. Exclusions vary enormously in width: some bite only on external wall systems, others on anything connected with fire safety in a building above a stated height, and a few on any fire-related allegation whatever the discipline.

The wording is negotiable, and the negotiation depends on being able to describe exactly what the firm does and does not do in this space. Our page on these exclusions sets out the variants and what a good outcome looks like.

Net zero, performance guarantees and advisory creep

Sustainability and net-zero advice is the fastest-growing part of many building services practices and the least well understood by underwriters. The risk is not the technical work; it is the drift from advice into assurance — a report that reads as a prediction becoming a document the client treats as a guarantee, or a carbon figure that ends up in a funding covenant. Net zero advisory PI exposure works through where that line sits and how to keep reports on the right side of it.

Structuring the programme

Limit. Size it against contractual requirements, the value of the projects the firm works on and the realistic cost of remediating a services failure — not against fee income. Client appointments frequently specify a limit and a period for which it must be maintained.

Aggregation. Whether a repeated design error across a portfolio of similar buildings is one claim or many is decided by the aggregation clause, and for a firm doing repeat work on a standard product this is the most important sentence in the policy. See aggregation of claims.

Defence costs. Inside or outside the limit. Construction disputes are expensive to defend and costs inside a modest limit can consume it before liability is decided.

Retroactive date and run-off. Claims-made cover means the current policy answers for past work. A restricted retroactive date removes cover for the very projects most likely to produce a claim, and the extended Defective Premises Act limitation periods make continuity of cover more important than it has ever been.

Single project cover. Where one project is much larger than the rest of the book, or a client demands a limit the practice cannot justify annually, project-specific PI is worth considering.

What underwriters will ask

Expect questions on the fee split by discipline and by sector; the proportion of work on residential and higher-risk buildings; whether the firm takes dutyholder roles; the standard form of appointment and whether it is amended; whether fitness-for-purpose obligations are ever accepted; who checks and signs off designs; how the firm records advice and assumptions; and the position on fire safety scope. Answering these properly, in writing, before the market sees the risk is the difference between a negotiated exclusion and an imposed one.

Frequently asked questions

Does PI cover a fitness for purpose obligation?

Generally not. Professional indemnity responds to a failure to exercise reasonable skill and care. A contractual promise that a system will achieve a particular result creates a stricter liability that most wordings either exclude or simply do not reach, so the exposure sits with the firm. The fix is in the appointment, not the policy.

We do not design facades. Why does a cladding exclusion affect us?

Because fire safety exclusions are usually drafted by reference to the building or the allegation rather than the discipline. Services design touches compartmentation through penetrations, dampers, ductwork and smoke control, so a broad exclusion can capture work that has nothing to do with external walls. The width of the wording is negotiable and worth negotiating.

How much cover should a building services consultancy carry?

There is no formula and we do not publish figures. The limit should be driven by what client appointments require, the value and nature of the projects, whether work is done on higher-risk or residential buildings, and the realistic cost of putting a services failure right — which is often many multiples of the fee.

Why does the retroactive date matter so much for this discipline?

Because services defects frequently surface years after handover, and the limitation periods for Defective Premises Act claims relating to dwellings were substantially extended by the Building Safety Act 2022. Continuous cover with an unrestricted retroactive date is what keeps that historic work insured.

This page is general insurance information, not legal advice, and describes the position as at August 2026. Cover depends on the wording of the policy actually in force.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This page is general information, not advice on a specific policy.