Dundee's guide sets one number, and it is 18 metres
People expect a depth limit. Dundee doesn't publish one. The council's householder guidance, written to support Policy 11 of the 2019 Local Development Plan, has no 45 degree line, no maximum rear projection and no minimum gap to the boundary. What it does give is a distance. New facing windows on an extension should, as a general rule, sit more than 18 metres from the facing windows of a neighbour's habitable rooms.
Everything else is judged on the drawing in front of the officer. A rear addition should be no higher than the house and preferably lower. A side one should stay behind the building line, match the ridge and roof style, and leave you a way round to the back for bins and maintenance. Policy 11 also protects usable garden and parking. If a neighbour would be overshadowed, cut the height or depth, or pull the wall off the boundary.
There is one item people forget. The guidance tells owners not to build over existing Scottish Water pipes. Find out where they run before the foundations are drawn.
Houses, flats and the back green
Scotland's 2022 census found 47.3% of Dundee households living in a flat, against 34.4% nationally. That matters here because the Scottish permitted development order treats a building containing flats as something other than a dwellinghouse. A flat owner has no permitted development right to add floor space at all. Every flat extension is a planning application.
Ownership comes first. Under the Tenements (Scotland) Act 2004 the bottom flat includes the solum beneath it, and by default a back green attaches to the ground floor flat nearest it, unless the deeds say otherwise or the ground is a path serving other flats. Plenty of Dundee titles do say otherwise, so have a solicitor read them.
How each type of extension works on Dundee houses
Ordered from the simplest approval to the hardest, for a Dundee house rather than a flat. Each links to a full guide.
Single storey at the back. Class 1A covers most of these on a house outside a conservation area. Where any part comes within a metre of the boundary, the limit is 3 metres beyond the rear wall of a terrace and 4 metres on a semi or detached house, with eaves no higher than 3 metres and an overall height of 4.
Kitchen. Watch the 18 metre rule if wide glazing faces a neighbour's back windows across a short garden. Obscure glass or a high-level window usually solves it.
Planning and warrant. Check Class 1A or 1B first, then remember the building warrant is a separate approval. Building Standards at Dundee House issues it, and starting work without one is an offence.
Side return. Rarer here than in English cities, since more than half of Dundee's homes were flats at the 2011 count. On a semi, keep the new wall behind the front of the house and think hard before you close off the only route to the back garden.
Wrap-around. The side leg is the part the council looks at hardest, so match the roof and keep it subordinate. Either way, the extended house can't cover more than twice the original footprint, and no more than half the rear garden can be built over.
Open plan. Taking out a back wall on a stone villa in the West End or West Ferry is structural work under the warrant. The engineer's calculations go in with the application.
Two storeys. Class 1B keeps every part 10 metres from the boundary, which few city plots can manage, so expect to apply. Upstairs windows are where the 18 metre rule bites.
Ground floor bedroom. If the need is disability related, ask for an assessment by the council's Community Occupational Therapy Service before you design anything. Under the council's scheme of assistance, the bathroom part of an extension can qualify for mandatory grant. Dundee Care & Repair can make the referral.
Home office. A detached garden room in a conservation area is capped at 8 square metres of footprint under Class 3A. Attaching it to the house gets round that limit but makes it a planning application there instead.
Cost. We don't print Dundee prices. Stone walls, a deeds check on a flat and a sloping site each move the figure, so get three builders to look at the job.
Flood maps, protected trees and sloping gardens
Flooding is patchy. A flood risk assessment prepared for the 2019 plan names three local problem areas. The Dighty Water has flooded homes around Ardler and Baldovie (2009, 2012 and January 2016 are on record). The Invergowrie Burn catchment links to the Lochee and Fowlis Burns. The Tay shore from Riverside Drive to Broughty Ferry carries the coastal risk. Policy 41 steers new development away from medium and high flood likelihood. It says nothing specific about extensions, so look at SEPA's flood map and raise it with the planning duty officer before you pay for drawings.
Trees catch people out in the 17 conservation areas. You must give the council six weeks' written notice before felling or pruning one, and any application has to show existing trees and how they will be protected during the build. Broughty Ferry's 2025 appraisal also prizes its large rear gardens and old boundary walls.
Then there is the hill. Around the Law Terraces and the Crescents, houses sit on steep slopes and back gardens rarely run level. Permitted decking stops at a floor level of 0.5 metres, measured from the lowest adjacent ground, so a raised terrace off a new kitchen often needs consent of its own.
Where these facts come from
- Dundee City Council: Householder Development supplementary guidance (LDP 2019, Policy 11)
- Scottish Government: Circular 1/2024, householder permitted development (dwellinghouses)
- Scottish Government: Circular 1/2024, flats
- Tenements (Scotland) Act 2004, section 2
- Tenements (Scotland) Act 2004, section 3
- Dundee City Council: 2022 Census profile
- Dundee City Council: LDP 2019 Strategic Flood Risk Assessment
- Dundee City Council: tree protection legislation
- Dundee City Council: Broughty Ferry conservation area appraisal 2025
- Dundee City Council: Scheme of Assistance (2017)
- Dundee City Council: Building Standards contacts
- mygov.scot: building warrants
- Midlothian Council: do I need a building warrant (exempt conservatories and porches)
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Questions people in Dundee ask
We have the ground floor flat with the back green. Can we build into it?
Possibly. By default under the Tenements Act the back green goes with the nearest bottom flat, but your title deeds can make it shared, and a path serving the other flats is excluded. Even if it is yours, a flat has no permitted development rights to extend, so you will need planning permission and a building warrant.
We live near the Dighty in Ardler. Will flood risk stop an extension?
Not automatically. The council's flood study names the Dighty around Ardler and Baldovie as an area with a history of flooding. Check SEPA's flood map for your address and ask the planning duty officer at planning@dundeecity.gov.uk before you commission drawings.
Does a small glass porch or conservatory need a building warrant?
Not always. A single-storey conservatory or porch of 8 square metres or less, at least a metre from the boundary, with safety glazing and no heating appliance, sink or toilet, is exempt. It still has to meet the building standards. For planning, a porch under Class 1C stops at 3 square metres and 2 metres back from a road.
There's a mature tree at the bottom of our West Ferry garden. Does that matter?
Yes. West Ferry is a conservation area, so the tree is protected and you must give the council six weeks' notice before any work to it. A Tree Preservation Order makes damaging it far harder to justify.