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Contractors who design
Garage and shed erectors need professional indemnity insurance if they design bespoke buildings, specify bases, advise on where a building can go or tell customers that no permission is needed. Erecting a kit building exactly to the manufacturer’s instructions carries less professional risk, but siting and base advice is still yours. Public liability covers accidents on site; it usually won’t pay to move, lower or re-base a building because your advice or design was wrong.
Part of: Professional indemnity for design and build contractors
In short
The PI risk for garage, shed and garden room businesses sits in the advice and design that come with the building. In England, a detached single-storey building of more than 15 m² and up to 30 m², with no sleeping accommodation, is exempt from the Building Regulations only if it is at least a metre from the boundary or substantially non-combustible. Permitted development limits outbuildings within two metres of a boundary to 2.5 metres high. The Party Wall Act requires notice before building on the boundary line. Get any of these wrong and the customer’s loss is financial, which public liability usually won’t cover.
Last reviewed 5 October 2026 by the Apex professional indemnity team.
A garage or shed looks like a product, but the customer is often buying your judgement as well: which building suits the plot, where it can go, what base it needs and whether anyone has to approve it. When that judgement is wrong, the loss is usually financial. The building has to be moved, cut down, re-based or put through a retrospective application. That is professional indemnity (PI) territory.
Public liability (PL) responds to accidents during the work: a panel dropped on a neighbour’s car, a customer who trips over your materials. It is not designed to pay for a building in the wrong place, or one that needed permission it never got. PL wordings usually exclude the cost of your own work and pure financial loss, and many exclude claims that something you supplied failed to perform.
How much PI matters depends on what you sell:
Read these as illustrative examples, not real claims. They show how disputes with garage and shed customers usually develop.
All five turn on advice or design, not accidents. That is why install-and-supply businesses in this trade still face PI claims.
These are the rules that decide whether a garage, shed or garden building was correctly advised on and designed. The building regulations and planning rules below apply in England; the Party Wall Act applies in England and Wales.
| Rule | What it says | Why it matters to you |
|---|---|---|
| Building Regulations 2010, Schedule 2, Class 6 | A detached single-storey building of no more than 30 m², with no sleeping accommodation, is exempt if no part is less than one metre from the boundary or it is built substantially of non-combustible material. A detached building of up to 15 m² with no sleeping accommodation is exempt wherever it sits. | Size, materials, use and position all affect the answer you give the customer. |
| Building Regulations 2010, Schedule 2, Class 7 | A ground-level carport open on at least two sides, with a floor area of no more than 30 m², is an exempt extension. Attached garages are not on the list. | Attaching a garage to the house changes the approval route. |
| Building Regulations 2010, regulation 9 | Part P (electrical safety) applies to an exempt detached building that takes its electricity from a dwelling, and parts of Part G apply if its water supply is shared with one. | Exempt buildings with power or water still carry compliance duties. |
| Town and Country Planning (General Permitted Development) (England) Order 2015, Class E | Outbuildings may not exceed 2.5 metres in height within 2 metres of the boundary, 4 metres with a dual-pitched roof or 3 metres otherwise, or 2.5 metres at the eaves. They cannot sit forward of the principal elevation, cover more than half the curtilage, or be built within the curtilage of a listed building. | The most common source of “you won’t need planning” disputes. |
| Party Wall etc. Act 1996, sections 1 and 6 | Building a wall on or up to the line between two properties needs notice at least one month before work starts. Excavating near a neighbour’s building or structure, within three metres and in some cases six, can also require notice. | The duty is the building owner’s, but customers rely on you to tell them it exists. |
| HSE guidance on asbestos | Asbestos may be present in any building built or refurbished before 2000, including asbestos cement roofs. Removing asbestos cement carefully, without breaking it up, is generally non-licensed work but still needs a risk assessment, trained workers and controls. | Taking down an old garage is not just demolition. It is a regulated task with its own insurance problems. |
Most siting mistakes come down to four measurements. Learn them, write them on the survey sheet, and record which applied to each job.
Use, materials and the property’s status change the answer too. Sleeping accommodation removes the small-building exemption. Listed buildings lose the outbuilding allowance in their curtilage, and the government’s householder guidance notes that councils can remove permitted development rights by an Article 4 direction or a planning condition. If you are not certain, tell the customer in writing to check with the council before they order.
Replacement jobs need one more check. HSE says asbestos may be present in any building built or refurbished before 2000, and asbestos cement roof sheets are a classic example. Removing them intact is generally non-licensed work, but it still requires a risk assessment, trained people and controls. Most PI and public liability policies exclude or restrict asbestos, so don’t assume either will respond if old sheets are broken up and a garden is contaminated. See the asbestos exclusion in professional indemnity.
| Usually covered by PI | Often excluded or limited | Needs a different policy |
|---|---|---|
| Negligent advice on planning, building regulations or party wall notices | Asbestos, including disturbance during demolition | Accidental injury or damage during erection (public liability) |
| Wrong specification of bases and foundations | Remedying your own defective workmanship | Injury or damage caused by a building you supplied (products liability) |
| Design errors in bespoke buildings, such as spans and roof loadings | Manufacturers’ and suppliers’ product guarantees | Injury to your own staff (employers’ liability) |
| Inaccurate statements about approvals in quotations or sales material | Contract terms promising more than reasonable skill and care | Vans, cranes and lifting equipment (motor and plant policies) |
| Defence costs, including surveyors’ and planning consultants’ reports | Claims arising from circumstances you knew about before cover began | Stock and display buildings at your premises (property cover) |
Many erectors buy PI as an add-on to a trade policy. If so, check the limit, and check that the business description covers design and advice rather than erection alone. Every policy is subject to the insurer’s acceptance and its terms.
Homeowners rarely ask for a PI certificate, so you will normally choose the limit yourself. Size it on a bad but realistic claim: dismantling and re-erecting your largest building, a new base, the neighbour’s surveyor and legal costs, and any planning consultant the customer hires. Schools, councils, sports clubs and commercial customers may set a minimum in their terms, and main contractors will set one in subcontracts.
Cover needs to last beyond the job. PI is claims-made, so a complaint about a garden room you put up three years ago is handled by whichever policy you have when it arrives. Planning enforcement in particular can come years later, after a neighbour complains or the house is sold. If you retire or close the business, run-off cover protects the work you have already done.
Sole traders are common in this trade, and the same rules apply to them. See PI insurance for sole traders.
A complete proposal gets better terms than a bare one, and a broker can only present what you tell us. Have these ready:
Speak to a broker
PI for garage and shed erectors, placed by a named broker
Start the online proposal and save it as you go, or leave your number and a named broker will call you back, usually the same working day.
Apex Insurance Brokers is an independent insurance broker based in Bristol, established in 2009 and authorised and regulated by the Financial Conduct Authority. We are not tied to one insurer: we work with over 30 markets, including Lloyd’s syndicates through wholesale brokers, and every client has a named broker who handles the placement, mid-term changes, certificates for clients and the renewal.
If you design buildings, specify bases or advise customers on siting, planning or building regulations, you should have it. Public liability covers accidents during erection, but it usually won’t pay to move, lower or re-base a building because your advice or design was wrong. PI responds to those claims, subject to the policy terms.
No. No law requires garage, shed or garden building businesses to hold PI, and most homeowners don’t ask for it. Schools, councils, commercial customers and main contractors may require it in their contract terms, sometimes with a minimum limit.
Your design risk is lower, but customers still rely on you for siting, base preparation and what they need to tell the council. Wrong answers on any of those can lead to a claim for moving or altering the building, which PL won’t usually meet.
The customer is responsible for getting permission, but if they relied on your advice that none was needed, they may claim the cost of a retrospective application, alterations or removal from you. PI can respond to that claim, subject to the policy terms.
Usually not. Most PI and public liability policies exclude or restrict asbestos claims. HSE guidance says asbestos may be present in buildings built or refurbished before 2000, so check for asbestos cement before you quote and follow HSE guidance if you remove it.
Public liability won’t usually pay to replace a defective base you laid, and PI rarely pays to rectify your own workmanship. If the customer alleges your base specification was negligent and claims the loss that followed, PI may respond, subject to the policy terms.
Apex arranges professional indemnity insurance for garage and shed erectors across the UK. Tell us about your work and we’ll find cover that fits. Or call 0117 325 0027.
Start your PI proposal Call 0117 325 0027Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Registered in England and Wales, company number 07014570. This page is general information, not advice on your individual circumstances. Cover is always subject to the insurer’s acceptance and the policy terms, and this page does not guarantee that cover will be available or on what terms.
