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Roof Lantern Upstand Details

Our roof lanterns are designed to be fixed onto a kerb-like detail which rises proud of the supporting flat roof assembly, precisely at the open edge of the lantern aperture.This kerb is called an upstand, the outside face of which allows the flat roofs external surfacing to lap up and form a weather-tight junction.

Whether creating an aperture within an existing flat roof, or detailing one within an entirely new construction, all works associated with the supporting flat roof, the formation of the upstand, external weathering finishes and internal linings and decorative finishes, are to be performed by others.


Typical Section through Flat Roof.

The accompanying drawing shows a typical section through an upstand at the aperture within a flat roof. Always ensure actual build meets with all current regulations / good building practice.

Materials and works to be carried out by others:

1. 2 No. joist trimmers (Size of trimmers will vary depending on their span. Steel channels or I-beams will be required on very large projects. Always consult a structural engineer).
2. Timber joists (The size of the joists will vary depending on the required span).
3. 75mm wide upstand frame constructed from 75mm x 45mm Timber Infilled with 75mm Polyurethane insulation (Such as Celotex or Kingspan).
4. 12.5mm plasterboard and skim finish, or panelled timber lining to individual preference.
5. Firring pieces of diminishing depth to create fall to the roof weathering surface.
6. Vapour control layer fitted between joists and insulation.
7. 125mm (min) Polyurethane insulation (such as Celotex or Kingspan).
8. 18mm exterior grade ply or OSB3 Board.
9. 15mm exterior grade ply.
10. External weathering finish to individual preference.
11. Code-5 lead upstand flashing.
12. 12.5mm plasterboard and skim finish, or panelled timber lining to individual preference.

Components to be installed by Just Roof Lanterns*:

13. 100mm x 25.5mm timber packer.
14. Roof lantern sill/plate.
15. Bull-nose detail.
16. Rafter.
17. High-performance glazing unit.
18. Aluminium skirt.
19. Aluminium glass end closure.
20. Aluminium rafter capping.

*Applicable to roof lanterns from the Classic Collection