PE foam fillers under trapezoidal sheeting

What a PE foam filler is

It is a strip of closed-cell polyethylene foam, cut precisely to the shape of a particular trapezoidal sheet. Closed cells mean the foam does not soak up water like a sponge. The filler fits between the sheeting and a flat surface: a trim, ridge cap, eaves flashing or masonry.

There are two basic versions:

• top filler follows the ribs from above and is used under the ridge cap and under flashings,
• bottom filler fills the ribs from below, for example above the eaves flashing or on a purlin.

Where they go

On tile-effect metal roofing and on ventilated ridges, a ventilated ridge strip is often used instead of a solid filler; it keeps rain out but lets air through. The MASLEN and Ruukki installation guides both allow for a ventilated ridge strip – if the roof is designed to be ventilated, a solid PE filler would block the ventilation.

Choosing the right filler

1. Find out exactly which trapezoidal sheet you have (manufacturer and type, e.g. rib height and cover width). A filler that “nearly fits” leaves gaps.
2. Decide whether you need a top or bottom filler.
3. Check whether the roof or wall needs to be ventilated at that point.
4. Lengths can be cut with a knife and are butted together without a gap.

Points to remember

• A filler does not replace a flashing; it only improves the seal beneath it.
• Against pitch and wind, what matters is that the trim presses the filler down; the filler holds nothing in place by itself.
• When replacing old, crumbling fillers, check the nearby screws with old washers too – they are usually in the same state.

• Butyl tapessealing side and end laps
• Flashing trimswhat goes on top of the filler