If your client asks you for proof of professional indemnity insurance for a construction project and you’re wondering – do I need it and what does it cover? You’re not alone.
Many contractors carry robust contractors all risk (CAR) and public liability cover, assume they’re protected, and then get caught out the moment a client’s procurement team asks for a PI certificate.
We delve into what professional indemnity insurance in construction covers, who needs it, and where the gaps tend to appear.
Who Needs Professional Indemnity Insurance?
PI insurance isn’t just for architects; in construction in the UK, you need it if your work involves any element of advice, design, or specification – not just physical build.
That includes:
- Design-and-build contractors who take on design responsibility as part of the contract
- Architects and structural engineers
- Project managers making decisions that affect cost, programme, or specification
- Specialist consultants (M&E, fire engineering, façade, geotechnical)
- Specialist tradespeople who specify materials, systems, or methods rather than simply installing to someone else’s design
If a client could reasonably argue that a mistake in your advice, design, or specification cost them money, you need the protection that professional indemnity insurance provides.
This is the core distinction contractors often miss: PI insurance responds to financial loss caused by human error, not to something falling.
If you take on a design-and-build contract, your client’s relationship is with you, not with the architect or subcontractor who produced the drawings. If a design problem surfaces after the project is completed, the client will usually come to you first, because that’s who they hold a contract with.
Whether you can then recover costs from a subcontracted designer depends on what you agreed with them and whether they were carrying adequate cover of their own.
This is why main contractors ask their designers and specialist subcontractors for evidence of PI insurance as a condition of appointment, and why you should expect to be asked the same by the person above you in the chain.
What PI Insurance Covers
Professional indemnity insurance protects you against claims that arise from:
- Negligent advice: for example, a foundation solution that is not suitable for the ground conditions
- Design errors: a structural miscalculation that requires expensive remedial work, even if it’s caught before completion
- Specification failures: specifying a cladding or insulation system that doesn’t meet building regulations or performance requirements
- Intellectual property infringement: using a design, drawing or process without the right to do so
The common thread is financial loss caused by a professional failure, not physical damage. A client suing because your design error meant they had to spend an extra £150k on remedial works is a PI claim, even if nothing was ever unsafe or broken.
What PI Insurance Does Not Cover
PI insurance construction policies typically exclude:
- Physical damage: to the works, site, or third-party property – this sits with your CAR or public liability policy
- Personal injury: covered by employers’ or public liability insurance
- Deliberate acts: PI responds to negligence and error, not intentional wrongdoing or fraud
There’s another nuance worth flagging: most PI policies exclude fitness-for-purpose obligations.
Standard professional appointments typically only require you to exercise “reasonable skill and care” – the standard a court would expect of a competent professional.
But some construction contracts go further and require the finished works to be fit for a specific purpose, regardless of whether reasonable care was taken. Most PI insurers won’t cover a fitness-for-purpose obligation, because it’s a stricter standard than professional negligence.
If your contract includes fitness-for-purpose wording, it’s worth having it checked against your policy before you sign.
This is one of the most common gaps that surfaces at claim stage, when it’s too late to fix.
How PI Insurance Fills the Design-and-Build Gap
Contractors moving into design-and-build contracts pick up design responsibility –often through an architect or in-house design input, without realising their existing CAR policy simply wasn’t built for it. CAR covers physical loss or damage during construction. It does not cover the financial consequences of a design error.
This means a contractor can be fully insured on paper and still be exposed the moment a design decision goes wrong.
Contractor professional indemnity insurance is what fills that gap. If you’re bidding for or have signed a design-and-build contract, and you don’t hold PI, this is worth addressing before a client’s due diligence flags it for you.
How Much PI Cover Do You Actually Need?
There’s no fixed answer – but in practice, the client usually tells you. Most construction contracts and tender documents specify a minimum limit of indemnity, and it’s often driven by the value and risk profile of the project rather than a generic industry figure.
On smaller jobs this might be as low as £250,000 per claim; on larger or higher-risk design-and-build projects, clients may require £1 million, £5 million or more.
Two details in the policy wording matter more than the headline limit:
- Aggregate vs any-one-claim cover: an ‘aggregate’ limit means the full sum insured is shared across all claims made in the policy year – so if you have two claims, they’re drawing from the same pot. An “any-one-claim” basis gives each individual claim access to the full limit, which is broader (and more expensive) cover.
- Whether legal costs sit inside or outside the limit: some policies pay defence costs from the same limit as any damages; others provide costs in addition to the limit. On a large claim, legal costs alone can be substantial, so this affects how much protection you have left.
Underwriters set your premium based on your turnover, the extent of design responsibility you’re taking on, the type of construction work involved, and your claims history. Two contractors with the same limit of indemnity can pay very different premiums depending on risk profile.
Collateral Warranties and PI: What to Watch For
If you’re working on a design-and-build contract, you’ll likely be asked to sign a collateral warranty – a separate legal agreement giving a third party (a funder, tenant, or future owner) the right to sue you directly, even though they weren’t party to your original contract.
Collateral warranties commonly require you to maintain a specified level of PI cover for a set number of years, often matching the limitation period for the type of contract you’ve signed.
The catch: PI insurance is renewed annually, and cover, wording and even which insurer you use can change every year.
A collateral warranty can commit you to maintaining a certain level of cover for 10–12 years after the warranty is signed – regardless of what happens to your business or your insurance arrangements in the meantime.
Before signing, it’s worth checking that the limit and duration you’re committing to are realistic for your business to sustain, not just what got you the contract.
Run-Off Cover: Why PI Can’t Just Stop at Handover
Unlike CAR or public liability, PI insurance needs to continue well after the project ends. Design and specification defects often don’t surface until years later.
Because PI operates on a ‘claims-made’ basis, rather than the ‘occurrence’ basis used by most other commercial insurance, you need a policy in place at the time a claim is made, not just at the time the work was done.
If you don’t hold a live PI policy the day a claim lands, it doesn’t matter if you were fully insured when the work was carried out – it’s the same as not having cover at all.
This is why run-off cover matters. If you stop trading, change your insurance structure, retire, or simply let a policy lapse, you can be left exposed to claims relating to work completed years earlier.
Expectations vary by contract type: many professional bodies and standard warranties expect run-off cover of at least six years to match the standard limitation period for contracts, while structural design work – where defects can take much longer to surface – often carries expectations of 12 years or more, in line with the limitation period for contracts under seal (deeds).
If you’re winding down a business or changing insurer, it’s worth checking what run-off period your existing contracts and warranties commit you to, rather than assuming a standard term applies.
Getting the Right Cover in Place
If a client has asked you for proof of PI insurance construction cover, it’s a fair question and a standard one on design-and-build and specialist trade contracts. The right policy depends on the scope of design responsibility you’re carrying, not just your trade.
Find out more about professional indemnity insurance and get a tailored quote.
