Domestic oil tanks and the Class E container limit

A domestic heating oil tank is permitted development under Class E of Part 1 of Schedule 2 to the GPDO 2015, which covers buildings and other structures incidental to the enjoyment of a dwellinghouse and specifically includes a container used for domestic heating purposes. The oil tank permitted development limit that matters most is capacity: 3,500 litres. Above that figure the right falls away, and the same number brings the tank inside the oil storage pollution regulations.

The container provision in Class E

Class E is the outbuilding class, and the drafting treats a container alongside a shed, a greenhouse and a swimming pool. The container has to be used for domestic heating purposes, for the storage of oil or liquid petroleum gas, and it has to be within the curtilage of the dwellinghouse.

Two consequences follow from that framing. First, the tank counts towards the cumulative limit on the area of ground covered by buildings, enclosures, containers and pools within the curtilage, excluding the original dwellinghouse, which must not exceed half the curtilage area. On a small plot already carrying a garage and a shed, that limit can be reached.

Second, the tank must not be situated forward of a wall forming the principal elevation of the house. A tank in the front garden needs permission, which is why they end up at the side or rear even where the delivery tanker has an easier run at the front.

Capacity and height limits that apply

The figures are specific, and the article 2(3) restriction sits underneath them.

Most domestic oil tanks sold in the UK sit between 1,000 and 2,500 litres, so the capacity ceiling is rarely the binding constraint on a single tank. It becomes one where an owner wants a larger tank to buy oil in bulk, or where two tanks are installed and the capacities add up.

Height catches bunded vertical tanks on a plinth. A tall slimline tank raised on blocks to give the fall needed for the feed line can exceed 2.5m overall where it sits close to a boundary, and the measurement is to the highest part of the structure.

Siting relative to boundaries and buildings

Planning limits and fire separation distances pull in different directions, and both have to be satisfied.

• The Class E height limit tightens within 2m of the curtilage boundary.
• Approved Document J sets separation distances for oil storage, commonly cited as 1.8m from a building with inadequate fire resistance and 760mm from a boundary, with a fire wall as the alternative where those distances cannot be achieved.
• The tank needs a level, non-combustible base extending beyond its footprint, usually a concrete slab.
• The delivery driver needs to reach it with a hose run within the length the supplier can manage, and that distance is a practical constraint people discover after installation.
• The feed line to the boiler should be as short and as protected as possible, with a fire valve.

Put the tank where all five work, not where it is least visible. A tank sited for appearance and then relocated is two installations.

Bunded tanks and the pollution rules

An integrally bunded tank, a tank within a tank, is the standard specification for new domestic installations and is what most installers and insurers expect. The outer skin contains a leak from the inner one.

The regulatory line sits at the same 3,500 litre figure. The oil storage regulations that apply to industrial, commercial and institutional sites also apply to domestic oil storage above 3,500 litres, which brings requirements for secondary containment and for the position of fill points and vents. Below that figure the regulations do not bite, which does not make an unbunded tank a good idea.

A leak is a contaminated land problem, and an expensive one. Heating oil migrates through soil, reaches groundwater and gets into neighbouring property, and remediation of a domestic spill can exceed the value of the heating system many times over. Where a site has a history of oil storage and a conversion or new dwelling is proposed, the investigation route is set out on the Contaminated Land Assessment page, and reports of that kind have to be prepared by suitably qualified and experienced persons in accordance with BS 10175.

And check the position of any well, borehole or watercourse before siting. A tank in a groundwater source protection zone deserves more care than the minimum specification.

Tanks on article 2(3) land

On article 2(3) land, which covers conservation areas, National Landscapes, National Parks, the Broads and World Heritage Sites, Class E is narrowed in one way that catches rural properties repeatedly.

A building, enclosure, container or pool within the curtilage must not be situated more than 20m from any wall of the dwellinghouse. On a smallholding or a converted farmhouse with a large curtilage, the obvious tank position in a corner behind a hedge is frequently beyond 20m, and that makes it an application rather than permitted development.

The rest of the Class E conditions apply as normal, so the capacity and height limits still bind. An Article 4 direction can also remove Class E rights, and for a listed building, listed building consent may be needed for works affecting its character or the character of a curtilage structure.

Fire separation and Building Regulations

Planning permission and Building Regulations approval are separate, and an oil tank installation needs attention to both even where no application is required.

The combustion appliance and fuel storage requirements in the Building Regulations apply, covering the tank base, separation distances, the fill point, the vent and the fire valve on the feed line. Installation by a registered competent person gives a documented route through that, and the paperwork matters when the property is sold.

For liquid petroleum gas the separation distances are set by the gas supplier's own requirements as well as by the Regulations, and bulk tanks are usually installed by the supplier to a fixed specification. The planning position is the same under Class E, since the provision covers oil and liquid petroleum gas alike.

Where capacity or siting needs an application

An application is needed where the capacity exceeds 3,500 litres, where the height exceeds the applicable limit, where the tank would sit forward of the principal elevation, where cumulative ground cover would exceed half the curtilage, where the tank would be more than 20m from the house on article 2(3) land, or where an Article 4 direction has removed the right.

The application itself is small. A site plan with the tank position and distances to boundaries and buildings, an elevation or manufacturer's drawing with dimensions and capacity, a note on the base and bunding, and a short justification covering screening and visual effect. Where the authority is likely to be concerned about appearance, offer planting or a screen as part of the proposal rather than waiting to be asked. The reasoning sits in a short Planning Statement.

Agricultural fuel storage is a different regime. Fuel tanks for the purposes of agriculture on an agricultural unit fall to be considered under Part 6 rather than Class E, with its own limits and a prior approval procedure for significant development, so a farm tank is not measured against the 3,500 litre domestic figure. Keep the two uses clearly separated, because a tank serving both the house and the farm invites an argument about which regime applies.

Only a lawful development certificate under section 192 of the Town and Country Planning Act 1990 formally confirms that proposed works are lawful without permission. Where you want to check which other documents a project might need, enter the postcode on PlanScope or browse the full list of report types.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it, and remember that a lawful development certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.