Do I Need Basement Works Included in My PI Policy?

If you’re an architect involved in designing or overseeing basements - even occasionally - the short answer is yes, you almost certainly need your Professional Indemnity (PI) insurance to include basement works.

Why Basements Matter So Much

Basement projects carry a disproportionately high risk compared to above-ground work. Here’s why insurers care - and why you should too:

• Ground movement / subsidence: Digging into the ground can destabilise neighbouring properties.
• Water ingress: Incorrect waterproofing design leads to damp, mould, and expensive claims.
• Structural failures: Mistakes in retaining wall design, underpinning, or piling can be catastrophic.
• Neighbour disputes: Basements often trigger boundary and party wall issues - and architects often get pulled into these by default.

What Happens If It's Not Included?

Many PI policies exclude basement works by default - or impose depth restrictions (e.g. no deeper than 1 metre, or no new basements at all).

If you carry out basement work and it’s not covered:

• Any claim - even if you’re not at fault - could be rejected outright
• You’ll be personally liable for the defence costs
• Your client could pursue you directly for rectification and loss of use

Even working on existing basement refurbishments (without new structural work) can fall into a grey area. It only takes one damp patch and an unhappy client for it to escalate.

How to Check Your Policy

Look for wording like:

• “Basement works excluded”
• “Work involving excavation deeper than X metres is excluded”
• “Cover excludes structural design or oversight of sub-ground construction”

If any of those apply, and you’re involved in basement design, your policy needs amending.

When You Definitely Need It

You should ensure basement cover is included if:

• You design new basements, cellars or below-ground levels
• You provide oversight or sign off on other parties’ basement designs
• You deal with basement conversions that impact structure, damp proofing, or services
• Your projects involve underpinning, piling, or significant excavation

Even if you're not the structural engineer, if your name is on the design team or you’re providing contract administration, you’re a target in any claim.

What It Typically Costs

Premium increases for including basement work vary depending on:

• Depth and complexity
• % of your annual work that involves basements
• Whether you use external engineers

In some cases, it can be a small loading. In others, insurers may require additional endorsements or apply higher excesses. But that’s still better than facing a 6-figure claim uncovered.

Get Advice From A Specialist

If you ever touch basement projects, and your PI policy excludes them - your business is exposed. It's one of the most common blind spots for smaller firms and sole traders.

A conversation with a broker who understands architectural PI insurance is essential. Don’t assume you’re covered. Click the button above to submit your details and discuss with an experienced broker.