Professional indemnity insurance for building services consultants protects mechanical, electrical, sustainability and other M&E specialists against claims arising from design or advisory negligence. Cover is required by most public-sector contracts and many private clients, and the risk picture has tightened materially under the Building Safety Act 2022.
A small Bristol-based M&E practice took on what looked like a straightforward commission in early 2023: full mechanical, electrical and public health design for a six-storey mixed-use scheme on the edge of a regional city. The building topped out at 19 metres — comfortably below the 18-metre higher-risk threshold introduced by the Building Safety Act 2022, or so the team thought. Three years later, with the scheme occupied, the developer’s solicitors wrote to the consultancy asserting that smoke ventilation provisions in the residential cores were non-compliant with Approved Document B and that remediation would run into seven figures. The practice’s professional indemnity policy, renewed each year on essentially the same terms since 2019, now contained a fire-safety exclusion that had crept in at the 2022 renewal without anyone in the practice quite registering its breadth. The claim sits, at the time of writing, with the firm’s directors personally exposed.
Stories like this have become uncomfortably familiar across the UK building services sector. The combined effect of the Building Safety Act 2022, the extension of limitation under the Defective Premises Act, sustained pressure on the professional indemnity market, and the rapid emergence of new advisory work around net zero has made PI a far more complex purchase than it was a decade ago. For mechanical, electrical, public health, sustainability, BREEAM, Passivhaus, façade and fire engineering consultancies, the policy that protects your balance sheet now needs scrutiny it has rarely received before.
This guide sets out, from a broker’s perspective, what professional indemnity insurance for building services consultants typically covers in 2026, where the market sits, and where we have seen consultancies expose themselves unnecessarily. It is general guidance rather than advice on any specific contract or policy — every placement turns on its facts, and underwriters approach the same risk differently. But if you sit on the technical or commercial side of a UK building services practice, the issues below should be on your desk.
The regulatory and commercial backdrop
The Building Safety Act 2022 is the single most consequential piece of legislation for the sector in a generation. It established the Building Safety Regulator within the Health and Safety Executive, created the gateway regime for higher-risk buildings (HRBs), introduced statutory dutyholder roles modelled on but distinct from the CDM 2015 framework, and — through amendments to the Defective Premises Act 1972 — extended the limitation period for claims relating to dwellings to 15 years prospectively and 30 years retrospectively for completed works.
For a building services consultancy, that backdrop matters in several practical ways. The gateway regime — Gateway 1 at planning, Gateway 2 before construction, Gateway 3 before occupation — has lengthened programmes and shifted design-acceptance risk firmly toward the design team. Information that previously sat in coordination drawings or contractor RFIs is now expected in a “golden thread” of structured digital information. The principal designer role under the Building Safety Act sits separately from the CDM principal designer, and where an M&E consultancy is appointed as the principal designer for building regulations purposes on an HRB it inherits coordination and competence-assurance duties with sharp teeth attached.
Outside the HRB cohort, scope creep is the quiet story. Many local authorities, lenders and warranty providers now ask for HRB-equivalent evidence on Category 2 and 3 buildings — student accommodation, care homes, hotels and even some commercial schemes — that fall outside the strict statutory definition. The cluster article on M&E design under the Building Safety Act explores the gateway and dutyholder issues in more depth.
CIBSE, the IMechE and the IET continue to publish the technical guidance that defines the standard of care for M&E design — TM52 and TM59 for overheating, the CIBSE Guide series, the IET Wiring Regulations BS 7671:2018+A2:2022 and the various heat-network and low-carbon design guides. Courts will look to these documents when assessing whether a consultant met the standard of a reasonably competent practitioner in the relevant discipline.
On the energy and sustainability side, the regulatory and commercial environment has tightened in parallel. The Minimum Energy Efficiency Standard regulations have driven a continuing stream of remediation work and advisory engagement on commercial lettings. The Future Homes Standard and Future Buildings Standard, even where final implementation dates have shifted, have already changed the design conversation around heat pumps, ventilation strategies and operational energy modelling. The Advertising Standards Authority and Competition and Markets Authority have both been vocal on green claims, and an advisory report that overstates the carbon credentials of a scheme carries exposure that did not exist five years ago. Our companion piece on net-zero advisory PI exposure covers that ground in detail.
What professional indemnity insurance typically covers
Professional indemnity insurance — sometimes called professional liability or errors and omissions cover — responds to claims arising from the consultancy’s professional services where there has been, or is alleged to have been, a negligent act, error or omission. For a building services consultancy, that typically means cover for civil liability arising from design, specification, contract administration, surveying, energy modelling, sustainability advice, expert witness work, and the various adjacent services that a modern practice offers.
A standard PI policy usually responds on a claims-made basis. That means the policy in force when a claim is first made against you, or when a circumstance likely to give rise to a claim is first notified, is the policy that responds — not the policy in force when the original design work was carried out. The retroactive date, set out on the schedule, defines how far back the policy will look for the original wrongful act. For a long-established practice the retroactive date should usually sit at or before the firm’s first day of trading; for a newly formed entity that has taken on staff and work from a predecessor, retroactive cover for the predecessor’s work is a critical negotiation point.
Cover typically extends to defence costs, damages, claimant costs awarded, and certain mitigation costs. It does not, as a rule, extend to liquidated damages where these are a contractual rather than a damages liability, to the cost of correcting or completing the consultant’s own work, or to fines and penalties of a punitive character. Subject to underwriter assessment, extensions may be available for breach of confidentiality, intellectual property infringement, libel and slander, dishonesty of employees, loss of documents and certain regulatory defence costs.
Building services consultancies should pay particular attention to a handful of specific provisions: the position on sub-contracted design (where you have novated work to a specialist sub-consultant), on collateral warranties (almost universally now required by funders, purchasers and tenants), on Building Safety Act dutyholder roles, and on fire-safety and cladding-related work. These are the areas where market wordings vary most.
A hardened market and what it means for placement
The UK professional indemnity market for construction professionals tightened sharply from 2019 onward in response to the Grenfell Tower fire and the wave of cladding and fire-safety claims that followed. Capacity withdrew, premiums rose materially, deductibles increased, and underwriters introduced or broadened fire-safety and cladding exclusions across the board. Conditions softened modestly through 2023 and 2024 for cleaner risks but remained hard through 2024 and into 2026 for any practice with meaningful fire-safety, cladding or HRB exposure.
What does that mean in practice for a building services consultancy seeking cover today? Several things. First, presentation matters more than it used to. Underwriters now expect a clear narrative on the firm’s HRB exposure (current, projected and historical), on its quality-management procedures, on its approach to fire-safety design and coordination, on novation and design-and-build arrangements, and on its claims and circumstances history. A proposal form completed in haste is likely to generate either a decline or an aggressive set of exclusions and sub-limits.
Second, exclusions and sub-limits warrant line-by-line review. A blanket fire-safety exclusion can sweep up work that has no obvious connection to fire engineering — smoke ventilation, fire dampers, electrical containment passing through compartment walls, the specification of cable insulation. A cladding exclusion may extend, depending on its wording, to any external wall system, including rainscreens and façades on buildings the firm never thought of as cladding projects. Some markets offer partial write-back for specific projects or for non-HRB work; others do not. We discuss this in detail in the BSA cluster article.
Third, the choice of insurer matters more than the headline premium. A handful of markets continue to write building services PI with genuine appetite; others tolerate the class but will be quick to non-renew at the first sign of difficulty. The firms that have fared best through the recent cycle have generally been those whose brokers have built consistent relationships with two or three appetised markets over multiple years, rather than those who have shopped premium aggressively each November.
Common claim sources, with worked examples
Claims against M&E and sustainability consultancies arrange themselves into a few recurrent patterns. The examples that follow are anonymised composites drawn from market experience and are intended to illustrate the underlying issues rather than to describe specific incidents.
Design coordination failures. The classic M&E claim arises where mechanical, electrical, public health and structural elements have not been adequately coordinated, typically discovered on site when ductwork will not fit above the ceiling void or when service risers conflict with structural openings. A consultancy that produced an apparently complete design package but failed to identify clashes that a reasonably competent practitioner would have caught will struggle to defend the resulting costs. The defence often turns on the scope of services actually appointed — particularly on whether the firm was engaged for full coordination or for performance specification only — and on whether BIM coordination obligations were spelled out in the appointment.
Plant sizing — both directions. A consultancy that oversizes plant produces a system that wastes energy, fails to meet operational carbon targets, and may breach the energy performance metrics warranted in lender documents. A consultancy that undersizes plant produces a system that cannot meet comfort conditions on design days, generates complaints from end users, and may require expensive remediation. Both are claimable; both are common. Heat-pump sizing in retrofit residential schemes has been a particular source of dispute since 2022, as design teams have grappled with limited site survey data and ambitious operational carbon targets.
Fire-safety design gaps. A growing class of claims relates to the M&E interface with fire compartmentation and means of escape — smoke ventilation strategies that fail under scrutiny at Gateway 2, fire-dampers omitted where ductwork crosses compartment walls, electrical penetrations through fire-resisting construction without adequate firestopping detail, evacuation lift arrangements that do not meet the latest guidance. These claims sit at the heart of the hard PI market and are often the trigger for an insurer’s first conversation about non-renewal.
Performance-gap and in-use energy disputes. Where a consultancy has provided design-stage energy modelling — SAP, SBEM, dynamic simulation, NABERS UK design-for-performance work — and the building’s measured in-use performance falls materially short of the modelled figures, an increasingly common response from the developer or operator is a claim against the modelling consultant. The defensibility of these claims turns on the modelling assumptions, the contractor’s variations, the operator’s actual usage patterns and the clarity of caveats in the original report. The net-zero cluster explores this in depth.
Late changes during construction. A long-running source of dispute is the consultancy that produced a competent Stage 4 design, lost effective control of the project at novation to a design-and-build contractor, and then found itself named in a claim for design decisions made by the contractor’s specialist sub-consultants in Stage 5. Novation wordings matter; so do the practical communication arrangements after novation; so does the consultancy’s discipline about formally noting where it has lost design control.
Sizing the limit
There is no single right answer to the question of how much PI limit a building services consultancy should buy. The starting point is what the firm’s appointments and collateral warranties require. Main contractors on medium-sized schemes commonly require £5 million or £10 million; developers on larger schemes routinely require £10 million or £20 million; funders and institutional purchasers on flagship schemes may require £25 million or more. Where the limit is required on an each-and-every-claim basis rather than in the aggregate, the underwriting and pricing implications are significant.
A second consideration is the aggregation profile of the firm’s work. A consultancy that has designed twenty buildings on the same template — a developer’s standard apartment block, for example — faces the possibility that a single design defect surfaces across multiple projects, with each manifestation potentially aggregating into a single claim or, depending on the wording, being treated as separate claims that exhaust the aggregate limit collectively. The aggregation language in the policy schedule is therefore as important as the headline limit.
Third, fire-safety sub-limits have become standard. A policy may be issued with a £10 million aggregate limit but with fire-safety claims sub-limited to £1 million or £2 million, sometimes inclusive of defence costs. A consultancy with material HRB exposure needs to understand whether the sub-limit is realistic relative to the value of the schemes it has worked on, and whether the sub-limit is annual or per claim.
Fourth, the collateral-warranty stack. A consultancy that has issued collateral warranties to a funder, a purchaser, a tenant and a management company on the same scheme has four potential claimants for what is essentially the same loss. Whether those claims aggregate or stack against the limit depends on the policy wording, but the gross exposure can be material and is often underestimated.
Sizing the limit, in our experience, is best done as a structured conversation between the firm’s directors, its lawyers (or its lead appointment reviewer) and its broker, rather than as a number plucked from the previous year’s renewal. We are happy to facilitate that conversation as part of the placement process.
Run-off cover
Run-off — the continuation of PI cover after a firm has ceased trading, sold its business, or stopped offering a particular service — has always been important for construction professionals. The extension of limitation under the Defective Premises Act, as amended by the Building Safety Act, has made it critical.
For dwellings, claims relating to work completed after 28 June 2022 can be brought within 15 years; claims relating to work completed before that date can, in certain circumstances, be brought within 30 years. For a consultancy whose directors are contemplating retirement, sale or restructuring, the question of how to fund a meaningful run-off period for several decades is not academic. The market for long-tail run-off in the building services sector is thin; pricing is volatile; and securing cover for the full theoretically applicable limitation period is often impractical.
In practice, most consultancies aim to maintain run-off for at least six years (mirroring the simple-contract limitation), with longer periods purchased where the firm has had material residential or HRB exposure. Some firms structure succession so that an acquiring entity assumes the historic liabilities and the run-off question becomes one of contractual indemnity backed by the acquirer’s continuing PI programme. Others fund a single-premium run-off policy at the point of cessation. Each route has tax, legal and insurance implications that benefit from joined-up advice.
Choosing the right policy
A few features of the policy wording deserve specific attention beyond the question of limit and exclusions.
Defence costs in or outside the limit. Where defence costs are payable inside the limit, every pound spent defending a claim reduces the indemnity available to settle it. On a complex HRB claim with multi-year expert evidence, defence costs can run into seven figures and seriously erode a £5 million limit. Defence-costs-outside-the-limit wordings are increasingly difficult to obtain at competitive premium, but where the firm’s exposure profile justifies it, they merit pursuit.
Fire-safety and cladding exclusions, and whether write-back is available. As discussed above, the breadth of these exclusions varies materially between markets. Some insurers offer write-back for non-HRB work, for work pre-dating a specified cut-off, or on a project-specific basis subject to underwriting review. Whether write-back is worth pursuing depends on the firm’s exposure and the premium differential.
Retroactive date. Where a firm has changed entity — through incorporation, restructuring, merger or acquisition — the retroactive date is the single most important clause in the policy for historic exposure. Continuity of retroactive cover should be a non-negotiable feature of every renewal, and any proposed change should trigger an immediate broker conversation.
Sub-contracted design risk. Modern M&E projects routinely involve specialist sub-consultants — façade engineers, fire engineers, vertical transportation consultants, acoustic consultants — appointed either by the lead consultancy or by the contractor under design-and-build. The policy’s treatment of liability for sub-contracted design needs to align with the appointment structure: a wording that excludes liability for sub-contracted design will leave the firm exposed where it has accepted vicarious responsibility in its appointment.
Dishonesty, intellectual property, and cyber. These are usually adequately covered in standard wordings but are worth checking. Cyber cover within a PI policy is typically narrower than a standalone cyber product and should not be relied on as primary cyber protection.
How Apex acts as broker
We sit, by design, on the firm’s side of the table. As an independent UK broker authorised and regulated by the Financial Conduct Authority, Apex Insurance Brokers has access to specialist UK insurers for construction professionals’ PI and works with the panel of insurers that genuinely understand the M&E and sustainability sectors. Our approach to a building services consultancy placement typically involves three stages.
First, a structured presentation of the risk. We work with the firm’s leadership to articulate the practice’s profile — scale, sectors, HRB exposure, novation patterns, quality systems, claims history — in a way that gives underwriters the information they need to price the risk on its merits rather than against the worst-case stereotype.
Second, a market exercise across appointed insurers rather than a scattergun approach. Reputation in this market matters: a firm that has been shopped to twenty insurers in six months will struggle to obtain competitive terms thereafter, and we manage that carefully.
Third, contract and collateral-warranty review at renewal. Most claims that go badly do so because the underlying appointment was harsher than the firm realised at the time of signing. We will review main appointments, collateral warranties and novation deeds against the firm’s PI cover and flag where contractual obligations outrun what the policy actually delivers.
Where claims arise, we act as the firm’s advocate with the insurer — managing notification, supporting the panel solicitor relationship, and pressing for sensible settlement outcomes. We do not act for the insurer.
Frequently asked questions
Is professional indemnity insurance a legal requirement for building services consultants? There is no general statutory requirement, but in practice almost every appointment, collateral warranty and framework agreement requires it. Professional bodies including CIBSE strongly recommend appropriate cover, and the Building Safety Act dutyholder competence regime makes a robust insurance programme part of how a firm demonstrates that it is operating on a sound footing.
How much PI cover should an M&E consultancy carry? Limits are typically driven by appointment and collateral-warranty requirements rather than by an abstract risk calculation. Smaller commercial-fit-out and education practices commonly carry £2 million to £5 million; mid-sized firms with developer clients typically sit at £5 million to £10 million; firms with HRB or large residential exposure often carry £10 million or more. Aggregation, collateral-warranty stacking and fire-safety sub-limits all matter alongside the headline figure.
What is a fire-safety exclusion and does my policy have one? A fire-safety exclusion is a provision that removes or limits cover for claims arising from fire-safety design, specification, advice or coordination. The breadth varies materially. Many policies issued to construction professionals since 2020 contain some form of exclusion or sub-limit; the precise wording and any available write-back should be reviewed at every renewal.
Does the Building Safety Act 2022 affect my PI cover? Indirectly but significantly. The Act has lengthened the period over which claims can be brought against dwelling designers, extended dutyholder responsibilities, and tightened the regulatory regime for higher-risk buildings. Underwriters have responded with sharper HRB questions, broader fire-safety and cladding exclusions, and more cautious pricing of the long-tail.
What is run-off cover and when do I need it? Run-off cover continues PI protection after a firm has ceased trading, restructured or stopped offering a particular service. Given that claims against dwelling designers can now be brought within 15 years of completion (and in some circumstances within 30 years), retiring directors and acquired firms should plan run-off arrangements carefully.
Can I get PI cover for net-zero and sustainability advisory work? Yes, but the cover needs to match the scope of work. The PI policy should explicitly cover the advisory services the firm offers, and the appointment letters and reports should be drafted with the policy in mind.
How does Apex Insurance Brokers approach a building services PI placement? We act for the consultancy, not the insurer. We present the risk to a curated panel of appetised markets, review appointment and collateral-warranty wording against the policy, manage the renewal cycle, and act as the firm’s advocate when claims arise.
What information do underwriters typically want at proposal stage? A modern submission typically includes three years’ fee income split by discipline and sector, a breakdown of HRB and residential exposure, details of the largest current and recent projects, quality-management procedures, claims and circumstances history, and a clear statement of services. Supplementary information on fire-safety design protocols, novation patterns and sustainability advisory work is increasingly common.
Related guides
For deeper treatment of the regulatory exposure, see our cluster article on M&E design risk under the Building Safety Act. For the distinct claims profile of sustainability and net-zero advisory work, see PI exposure for net-zero advisory engineers.
About this guide. This article was prepared by Apex Insurance Brokers and last reviewed in May 2026. It is intended as general information for UK building services consultancies and is not advice on any specific contract, policy or claim. The professional indemnity market changes continually; the position described here reflects market conditions as we observe them in mid-2026.
Apex Insurance Brokers. Authorised and regulated by the Financial Conduct Authority, Firm Reference Number 724952. Registered in England and Wales, Companies House number 07014570. Registered office: Bristol. Email: info@apexinsurancebrokers.co.uk. Telephone: 0117 325 0027.