House or flat? Ask that before anything else
Scotland's householder permitted development rights let you add a single-storey extension, a taller one or a small porch without a planning application. But only to a house, and only outside a conservation area. The Scottish Government's circular is blunt. Flats get none of these rights.
In Glasgow that rules out most people. The Scottish Household Survey found just 31.4% of adults in the city living in a house or bungalow. The rest live in flats, and the definition is wider than people expect. A four-in-a-block upper or lower, a cottage flat in Knightswood, a villa split into flats. If another home sits above or below yours, you're a flat, even with your own front door and garden.
A flat can still be extended, with an application every time. Council guidance admits these jobs are awkward, with neighbours close and ownership tangled. It wants no new windows or doors right beside garden ground you don't own outright. And if you're on the ground floor of a tenement hoping to knock a private door through to the backcourt, forget it. That won't be supported.
The council's tape measure
Glasgow adopted its residential design guidance, part of SG1 Placemaking, on 29 October 2018. Every extension that needs planning is checked against its figures.
Keep at least 900mm between the extension and the side boundary so bins and the mower can still get round to the back. Leave at least 66% of the original usable back garden after everything is built, sheds and garages included. A single-storey extension is tested against the neighbours' windows with the 45-degree rule, drawn on both plan and elevation, and failing both is refused. Two storeys or more gets the vertical sky component test instead.
A two-storey side extension on a semi should be set back at least 1.5 metres from the front building line, with the eaves carried through and a lower ridge. The point is to stop a street of semis slowly joining up into a terrace. A corner plot can sometimes get that set-back relaxed. Pitched roofs are the default, though a flat roof on a single storey can pass if the design is good.
What each type means here. The full guides are written for the whole UK, so read them alongside the Scottish rules above.
The rules. For a house outside the 25 conservation areas, a single storey within a metre of the boundary can go 3m past the rear wall on a terrace, 4m on a semi or detached, with eaves no higher than 3m and the whole thing under 4m. A flat, or any home in a conservation area, means an application.
Single storey at the back. The natural fit for an inter-war semi in Riddrie, Mosspark or Knightswood, and often buildable without an application if you stay inside those limits and the 50% curtilage rule. On a tenement it always needs permission.
Kitchen. On a house, Glasgow's guidance won't accept frosted glass as a cure for overlooking. Decide where the glazing faces before you fall for a wall of it.
Open plan. Taking out the back wall of a stone semi or a four-in-a-block needs an engineer's beam design on the warrant drawings. In a flat, the external and load-bearing walls are shared scheme property under the Tenements Act, so the other owners have an interest.
Two storeys. Scottish rights for anything over one storey need every part to be 10 metres from the boundary, which few Glasgow plots can manage. Assume an application, and a rear one needs a ridge well below the house.
Wrap-around. Hard to square with the 900mm side gap the council asks for, unless the route to the back garden stays open through a garage or utility room. Talk to the planners early.
Side return. Rare here. This type was invented for narrow Victorian terraced houses, and much of Glasgow's Victorian housing went up as tenement flats instead. Where a side passage does exist, building into it collides with the 900mm rule.
Garden office. A detached building over 8 square metres in a house's garden needs a building warrant, as does one with a toilet or sleeping space. In a conservation area, the permitted footprint for an outbuilding drops to 8 square metres.
Ground floor bedroom. Often the answer for a cottage flat or ground floor flat where stairs have become a problem, but it's a planning application, and it needs a building warrant like any other new room.
Cost. No figures from us. In a flat, the solicitor's time on deeds and neighbours' consent belongs in the budget alongside the builder's. Get three quotes from people who have seen the site.
Warrants, old pits and the White Cart
Planning is only half of it. Nearly every extension also needs a building warrant from the council's building standards service, and in Scotland there's no private alternative. The exemptions are narrow. A conservatory or porch on a house can skip the warrant if it's under 8 square metres, more than a metre from the boundary, and has no toilet or stove. Widen the doorway into it and you need a warrant after all.
Ground matters too. The British Geological Survey's work on the Clyde Gateway area found old coal seams worked out completely, with stoop and room workings left open and flooded, under layers of made ground that change from one plot to the next. Planning won't usually ask a householder for a mining report, but your engineer should know where you are before designing foundations.
On the south side, the White Cart Water flood prevention scheme opened in 2011 and protects about 1,750 homes along a river that had flash-flooded more than 20 times since 1908. If your house is near a burn or river, check SEPA's flood maps. The council can ask for a flood risk assessment.
Where these facts come from
- Scottish Government: Planning Circular 1/2024, Classes 1A, 1B, 1C and 3A
- Scottish Government: Planning Circular 1/2024, flats
- Glasgow City Council: SG1 Placemaking Part 1 and Part 2
- Glasgow City Council: residential development quick guide (extensions, flats, conservatories)
- Glasgow HSCP: housing and household composition
- Glasgow City Council: conservation areas and appraisals
- Scottish Government: building standards technical handbook 2020 (domestic), exempted buildings
- Glasgow City Council: building warrant applications
- Tenements (Scotland) Act 2004, Tenement Management Scheme rule 1.2
- British Geological Survey: engineering geology of the Glasgow Clyde Gateway area
- Glasgow City Council: flood risk
- Urban Realm: White Cart Water flood prevention scheme
- Glasgow Life: Homes for heroes (Riddrie, Mosspark, Knightswood)
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Questions people in Glasgow ask
We have a ground floor tenement flat. Can we build out into the back green?
Only with planning permission, and only on ground your deeds give you. A shared backcourt isn't yours to build on. Nor will the council support a new private door from a ground floor flat into a communal backcourt.
Our Knightswood cottage flat has its own garden. Is a conservatory allowed without asking?
No. A cottage flat is a flat for planning, so there are no permitted development rights to extend it. The warrant exemption for small conservatories covers houses only, so you'll need a building warrant too.
Our semi isn't in a conservation area. Does the 45-degree test apply if we stay within permitted development?
The council applies its SG1 tests to planning applications. If your extension sits wholly inside the Class 1A limits, there's no application to test. A certificate of lawfulness gives a future buyer's solicitor written proof.
How close to the neighbours' fence are we allowed to build?
Within a metre of the boundary, Class 1A caps a rear extension at 3m past the back wall on a terrace or 4m otherwise. If you need planning, the council expects a 900mm gap at the side unless there's another route to the back garden.