Under the April 2026 domestic Technical Handbook, a single-storey conservatory or porch attached to a house can be built without a building warrant if it is 8 square metres or less, is at least 1 metre from a boundary and has no flue, fixed combustion appliance installation or sanitary facility.

The warrant exemption

The domestic Technical Handbook, April 2026 edition, applies in Scotland only. Its section 0.5 explains that regulation 5 and schedule 3 set out work that can be done without a building warrant, and that such work must still comply with the regulations. Building type 18 in the schedule covers a single-storey building attached to an existing house, ancillary to it, consisting of a conservatory or porch whose glazing complies with regulation 9 and paragraph 4.8 of schedule 5.

The exceptions to type 18 are a building exceeding 8 square metres in area, a building containing a flue, a fixed combustion appliance installation or a sanitary facility, and a building within 1 metre of a boundary. A conservatory outside those limits needs a building warrant, and mygov.scot says it is an offence to start work that needs a warrant without one.

What counts as a conservatory

Appendix A of the Handbook defines a conservatory as a building attached to a dwelling with a door and any other building elements dividing it thermally from that dwelling, and with translucent glazing (including frames) forming not less than either 75% of its roof area and 50% of its external wall area, or 95% of its roof area and 35% of its external wall area. The Handbook notes that the definition was amended on 1 May 2007. The Handbook adds that a conservatory allows natural light and ventilation to be borrowed through glazing and ventilators into adjacent rooms, which is why a large area of translucent material is required in its fabric, and that the definition should be read with the SAP 10 document.

Energy standards

Clause 6.2.11 says a conservatory should be thermally divided from the dwelling, outside its insulation envelope, and the dividing wall, door and window should have U-values equal to or better than the corresponding exposed elements of the house. Where not exempt, a conservatory, heated or not, should meet the same maximum U-values as other new work, except that the glazing and framing forming its walls or roof are unlimited in area, subject to a maximum area-weighted average U-value of 1.8 W/m2K and a maximum for any individual element of 3.3 W/m2K.

Clause 6.1.6 says conservatories under 50 square metres are stand-alone buildings thermally separated from the dwelling, while conservatories of 50 square metres or more subject to standard 6.1 need a non-domestic style SBEM calculation. The Handbook also says some smaller conservatories can be exempt from both a warrant and the standards, and that draught stripping on existing windows and doors between house and conservatory should match that of exposed windows and doors.

Ventilation and daylight

Clause 3.14.9 recommends that a conservatory have ventilators with an opening area of at least one fifth of its floor area, with high-level or roof vents best placed to reduce heat build-up. Where a conservatory is built over an existing ventilator serving a room, clause 3.14.11 says the conservatory’s ventilation must open to the outside air with an area of at least one twentieth of the combined floor area of the room and conservatory, and the room’s ventilator should be at least one twentieth of that room’s floor area. Clause 3.16.2 says a conservatory may be built over a translucent glazed opening if that opening is at least one fifteenth of the floor area of the internal room formed.

Fire spread and escape

Section 2 of the Handbook says short fire resistance duration is sufficient for a conservatory or porch attached to a dwelling even when it is within 1 metre of the boundary. It also says that where a conservatory is located below an escape window, consideration should be given to the design of the conservatory roof.

FAQs

Does a small conservatory in Scotland always avoid a warrant?

No. The exemption in building type 18 is limited to 8 square metres, at least 1 metre from a boundary, with no flue, fixed combustion appliance installation or sanitary facility.

Does the exemption remove the building standards?

No. The Handbook says work not requiring a warrant must still meet the standards required by the regulations.

Do planning rules matter too?

Yes, but they are separate. This guide covers the building warrant and building standards only.

Bottom line

In Scotland, only a small attached conservatory, 8 square metres or less, at least 1 metre from a boundary and without a flue, combustion appliance or sanitary facility, can be built without a building warrant, and even then the standards on glazing, thermal separation, ventilation and fire apply. Larger conservatories need a warrant. This is general information, not advice on a specific project; the local council’s building standards department can confirm what applies.

Sources

This guide draws on the following primary sources, current as of 21 September 2026:

• Scottish Government, “Building standards technical handbook: domestic, April 2026”
• mygov.scot, “Getting a building warrant”

Related guides

Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal or planning advice on any specific property — always confirm requirements directly with your local planning authority.