A log cabin sold as permitted development

A garden cabin enforcement walkthrough almost always starts in the same place: a supplier told the buyer that no planning permission was needed, and the buyer believed it. The supplier was not lying, exactly. Most garden buildings do fall within Class E of Part 1 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015. But Class E has height limits measured from a particular point, a boundary rule that catches almost every cabin pushed to the back fence, and a purpose test that a home office let to someone else fails. The walkthrough below is illustrative, assembled from the pattern these cases follow rather than from one real case.

What the owner was told at the point of sale

The brochure said "no planning permission required" and the salesperson repeated it. The cabin was 5 m by 4 m, with a shallow dual-pitched roof, a 1.2 m deep covered veranda and a timber deck across the front. It was delivered in two days and erected in one, 1.5 m from the rear boundary of a suburban garden, with the deck raised 450 mm to get over a slope.

And nothing in that transaction involved the council. Suppliers are not required to check anything, and a statement in a brochure is not a determination. Planning permission is not something a manufacturer can confer, and the liability for an unauthorised building sits with the owner of the land.

Where the cabin breached Class E

Three separate limits were exceeded, which is typical.

The height limit. Class E permits a building up to 4 m high with a dual-pitched roof and 3 m otherwise, but where any part of the building is within 2 m of the curtilage boundary the limit drops to 2.5 m overall. At 1.5 m from the fence, this cabin needed to be no more than 2.5 m high. It was 2.9 m to the ridge.

The raised platform. Class E does not permit a building that includes a veranda, balcony or raised platform, and a platform more than 300 mm above the ground counts. The 450 mm deck took the whole structure outside the class on its own, regardless of height.

The eaves. Where the 2.5 m rule does not apply, the eaves of an outbuilding must not exceed 2.5 m. Cabins sold on the basis of a 2.5 m eaves height often measure 2.55 m once they sit on a base, and the measurement is taken from the highest part of the ground next to the building, which on a slope is not where the installer measured.

Two further rules are worth knowing even though they did not apply here. Buildings, enclosures and containers in the curtilage must not cover more than half the curtilage, excluding the ground area of the original house. And in a conservation area, National Park or National Landscape, a building more than 20 m from any wall of the house is limited to 10 m² of ground area.

The neighbour complaint and the council's enquiry

The complaint came six weeks after installation, about the deck rather than the cabin. An enforcement officer visited, measured the ridge from the adjacent ground level, photographed the deck and wrote to the owner setting out the apparent breach and inviting a response.

That letter is not an enforcement notice. It is the point at which the position still costs little to fix. Owners who ignore it, or who reply that the supplier said it was fine, lose the only part of the process where the council has discretion and no formal timetable.

The enquiry also tested use. The owner's partner was running a dog grooming business from the cabin, with clients arriving by car. Class E only permits buildings required for a purpose incidental to the enjoyment of the dwellinghouse, and a business receiving customers is not incidental. That turned a dimensional breach into a possible material change of use, which the officer recorded separately.

The options once the breach was established

Four routes existed, with different costs.

1. Remove the cabin. Lowest professional fees, worst outcome for the owner, and the one an enforcement notice would eventually require.
2. Alter it to comply. Take the deck down to below 300 mm, lower the ridge or move the building more than 2 m from the boundary. Once compliant, no permission is needed and no application is required.
3. Apply retrospectively under section 73A of the Town and Country Planning Act 1990 for permission for development already carried out, which is judged on its planning merits like any other application.
4. Do nothing and rely on the passage of time. The Levelling-up and Regeneration Act 2023 extended the immunity period for operational development in England from four years to ten years for breaches occurring on or after 25 April 2024, so this is now a long wait and the building is unmortgageable in the meantime.

The business use added a fifth question. The dog grooming had to stop, or be applied for, because a retrospective application for the building alone would not authorise the use. The owner stopped it.

Option 2 is underrated. Lowering a ridge by 400 mm costs a joiner a day. The same reduction argued through a planning application costs more and can still be refused on overbearing grounds.

The retrospective application

The owner chose a retrospective application, because the slope made relocation awkward and the deck was the point of the building.

The submission was short: a location plan with the site edged red, existing and proposed block plans, elevations showing the as-built heights measured from the highest adjacent ground, photographs from the neighbour's garden, and a Planning Statement addressing the two issues the officer had raised. Those were overbearing effect on the neighbour's garden and the loss of light to a greenhouse. A section drawing through the boundary, showing the shadow cast at the spring equinox, did more work than any paragraph of policy.

Retrospective applications attract the same fee and the same publicity as an ordinary one. Neighbour objections arrive with the benefit of hindsight, which is why the design response matters. Where other works have already happened without consent, the same logic applies, and the sequence set out in the walkthrough of a self-build plot on a garden site shows how quickly an unauthorised start complicates a later application.

What the authority required

Permission was granted with three conditions, which is the usual shape of these decisions.

The deck was reduced to 250 mm above ground along the boundary side, with the balustrade removed. A 1.8 m close-boarded fence and a hedgerow planting strip were required along the shared boundary within three months. And the use was restricted to purposes incidental to the enjoyment of the dwellinghouse, with no trade or business from the building, which is the condition that mattered most to the neighbour.

Conditions on retrospective permissions bite immediately rather than before any start on site, so read them carefully. A three month compliance window on planting is normal and councils do check.

Checking a supplier's claim before you buy

Four things to do, in this order, before the deposit:

• Measure the intended position. If any part of the building will be within 2 m of a boundary, the whole thing must be 2.5 m or less in height, and that includes the base, the floor build-up and any deck.
• Check the designations. Conservation area, National Park, National Landscape, listed building curtilage and Article 4 directions all change or remove Class E rights. The council's online map is the source, and an Article 4 direction removing householder rights is more common than people expect.
• Read the government's permitted development rights for householders technical guidance on how each height is measured. The measurement point, not the dimension, is what catches people.
• If any doubt remains, apply for a certificate of lawfulness of proposed use or development under section 192 of the 1990 Act. It costs a fraction of a full application, takes eight weeks, and produces a binding confirmation that the works are lawful. A certificate is the only formal way to confirm that.

A supplier's assurance is worth nothing in front of an enforcement officer. Nor is a verbal comment from a planning officer at the counter. Get the certificate, or keep the building inside the limits by a margin rather than by a centimetre.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. If an application is the route you end up taking, browse the report types on PlanScope to see what a householder submission usually contains.