You want to build something in the garden - a home office, a gym, a workshop, somewhere to escape the house and actually get things done. You've found the perfect spot, but it's close to the boundary. And now you need to know: how tall can it be?
The answer is 2.5 metres. If any part of your outbuilding is within 2 metres of a boundary, the entire structure is capped at 2.5 metres total height - ridge, eaves, everything. No exceptions, regardless of roof type. Move it more than 2 metres from every boundary and you can go up to 4 metres with a dual-pitched roof.
Your outbuilding's maximum height depends on two things: how far it sits from the boundary, and what type of roof it has.
If any part of the building is within 2 metres of the boundary, the 2.5 metre limit applies to the whole structure - not just the part that's close.
This is where most confusion happens, especially on sloping sites. Height is measured from the highest point of the natural ground level immediately adjacent to the building.
If your garden slopes, you measure from whichever side of the building has the highest ground. It doesn't matter that the other side gives you more clearance - your council will measure from the high side. On a significant slope, this can eat into your usable internal height considerably.
"Natural ground level" means the original surface. If you've laid a patio, decking, or added soil to raise the level around the building, those additions are ignored. Conversely, if you dig down inside the building to create a lower floor, that doesn't increase your permitted height. The external measurement is all that matters.
Sloping ground - practical example
Your garden slopes 400mm from one side of the proposed outbuilding to the other. You measure 2.5 metres from the high side to the ridge. On the low side, the ridge is 2.9 metres above ground - but that's fine, because the legislation measures from the highest adjacent ground, not the lowest.
The 2-metre distance is measured from the boundary of your property's curtilage - the legal boundary, not necessarily where your fence is. If your fence sits inside the legal boundary, you need to measure from the actual boundary line.
The measurement is to any part of the building. The legislation defines "building" as including any structure or erection. In practice, local authorities typically treat roof overhangs, fascia boards, and guttering as part of the building. If you position your walls 2.1 metres from the boundary but your roof overhangs 200mm, a council may consider the building to be within 2 metres. Measure from the outermost projection to be safe.
If you already know where you want to build, the free eligibility check takes about two minutes.
The same rule applies. A shed, garage, garden room, or any other outbuilding follows identical height limits under Class E. If any part of the structure is within 2 metres of a boundary fence, the maximum height is 2.5 metres. There is no minimum distance from a boundary - you can build right up to the fence line, as long as the total height stays at or below 2.5 metres.
Most off-the-shelf garden sheds are under 2.5 metres, so the boundary distance only becomes an issue with larger structures. One practical point: even if the planning rules allow you to build against the fence, you'll want to leave enough space to maintain the building and treat the timber - most suppliers recommend at least 300-500mm clearance. And if the building is over 15 square metres and within 1 metre of the boundary, building regulations require it to be constructed from substantially non-combustible materials.
Meeting the height limit is necessary but not sufficient. Your outbuilding must also be single storey, positioned behind the principal elevation of your house, and for a purpose incidental to the enjoyment of the house - a home office, gym, workshop, or storage, not a separate dwelling. The total area of all buildings in your garden must not exceed 50% of the total curtilage. And if your property is in a conservation area, National Park, AONB, or World Heritage Site, additional restrictions apply. For the full rules, see our outbuildings guide.
Common mistakes that cost money
Measuring height from the internal floor. If you excavate to create a lower floor inside, the external height measurement doesn't change. The 2.5 metres is measured from the highest natural ground level outside.
Not accounting for roof overhang in the 2-metre distance. Local authorities typically measure to the outermost part of the structure. If your walls are 2.1 metres from the boundary but the eaves project beyond, the council may consider the building within 2 metres.
Assuming the fence is the boundary. Fences are often set inside the legal boundary. If you're close to the 2-metre threshold, download your title plan from the Land Registry for £3 to confirm.
PD Assessment Tool
A professional permitted development assessment from a planning consultant typically costs £400-600 and takes 2-3 weeks. This tool checks your specific project against every Class E condition and produces a formal document you can share with your builder or your council.
The first step checks whether your property is eligible - about two minutes, completely free. If your property qualifies, the full project assessment is £47.
Content verified against the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended), Class E of Part 1, Schedule 2 (legislation.gov.uk, revised version) and the government's technical guidance (September 2019). Fees confirmed as of 1 April 2026. SI 2026/313 confirmed no changes to Class E. This page is for general information only and does not constitute legal advice.
April 2026