Flashing trims
A flashing trim covers the place where two different surfaces meet. On a pitched roof that is where the covering meets a wall or chimney; on an industrial building it is where trapezoidal sheeting meets a window, the plinth or a corner of the building.
- Sheet
- Flashing trims
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- Sources
- 5 items
- Type
- information guide
Where flashing trims are used
| Trim | Function | What to watch |
|---|---|---|
| Side abutment flashing (wall running down the slope) | the roof runs alongside a wall; water flows past the wall | the flashing lies on the covering; the joint with the wall is sealed or covered by a counter-flashing |
| Top abutment flashing (wall above the roof) | the roof finishes below a wall | sheet turned up the wall, with a profiled filler beneath it to suit the covering |
| Counter-flashing (movement strip) | covers the top edge of a flashing on a wall or chimney | fixed into the wall, top joint sealed with permanently elastic sealant |
| External and internal corners | corners of industrial and facade cladding | joints lapped in the direction of water flow |
| Plinth drip | bottom edge of cladding above the plinth | drip fold clear of the plinth so water does not run down the masonry |
| Opening flashings | around windows, gates and doors in metal cladding | the head flashing must shed water outwards, not into the opening |
| Parapet upstand trim | finishing the cladding at a parapet | see parapet coping |
| Ridge and eaves closure profiles | top and bottom edges of the cladding | on trapezoidal sheeting, with a PE foam filler |
Roof-to-wall junction
- wall (masonry, possibly with external insulation)
- roof covering
- abutment flashing laid on the covering and turned up the wall
- profiled filler or sealing strip under the flashing (to suit the covering profile)
- counter-flashing set into a chase or fixed to the wall
- permanently elastic sealant in the top joint
- roofing underlay turned up the wall
- Drawing no.
- KV-07
- Title
- Roof-to-wall abutment, section
- Scale
- diagram
- Revision
- 14 October 2026
A roof-to-wall junction has two layers of protection. The first is the roofing underlay turned up the wall, the second the metal flashing. The flashing lies on the covering and is turned up the wall, and its top edge is covered by a counter-flashing. The MASLEN installation guide specifies, for a side flashing under the covering, screw fixings into the wall and sealing the joint with the wall.
On an insulated wall, decide in advance whether the trim goes into the insulation layer or onto the finished render. Insulation added later often covers the original counter-flashing, creating a spot where water runs behind the insulation.
Material and dimensions
Flashing trims are most often folded from pre-painted galvanised sheet 0.5 to 0.6 mm thick in the colour of the roof or cladding, commonly in 2 m and 3 m lengths. On a titanium-zinc or copper roof the flashings are made from the same metal so that no galvanic cell is created (see the material comparison).
For folded trims the price depends mainly on the girth and the number of folds. A trim with a 250 mm girth uses a quarter of a square metre of sheet per linear metre, plus waste from the sheet format.
Common mistakes
- the trim is screwed through a surface where water flows, instead of through the vertical leg or with clips,
- the counter-flashing has no sealant, or sealant not intended for outdoor use that cracks within a few years,
- laps the wrong way round: the upper piece tucked under the lower one,
- no expansion joints on long trims, which then buckle or tear at the joints.
Technical sources
The sources this sheet draws on. We checked prices and values from standards on the date shown; for prices, whatever the source currently states always applies. Sources marked “in Slovak” or “in Czech” are only available in that language.
| Item | Source | Published by | Version / date | Checked |
|---|---|---|---|---|
| 01 | Roofing installation instructions (valley, verge flashing, abutment flashings, ridge capping) (in Slovak) | MASLEN s.r.o. | 2021 | 14 October 2026 |
| 02 | Installation guide – Adamante, Monterrey, Finnera tile-effect roofing and trapezoidal sheets (flashings, valleys, eaves) (in Slovak) | Ruukki Slovakia s.r.o. | 2024 | 14 October 2026 |
| 03 | Making a chimney flashing – method statement (underlay min. 150 mm, counter-flashing strip, sealant) (in Slovak) | ASB.sk / Stavebné materiály | 26 July 2021, updated 19 April 2025 | 14 October 2026 |
| 04 | Chimney flashing: guide and details (underlay ~150 mm, drainage channel, movement strip, indicative prices) (in Slovak) | Všetkoprestrechu.sk (seller of the PorTec system) | 8 January 2026 | 14 October 2026 |
| 05 | Archived snapshots of the original klampiarskevyrobky.sk website (2012, 2013, 2016, 2018) (archived site in Slovak) | Internet Archive – Wayback Machine | 2012–2018 | 14 October 2026 |
- Prepared by
- KlampiarskeVýrobky.sk
- Revision
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