I've looked on the Timco site and there seems to be nothing saying which screw is appropriate for the valley of a corrugated steel sheet (standard 18mm corrugation height, 76.2 between peaks).
I've seen EDPM washers size 14mm, 16mm and 19mm, so are they all OK, or is one type preferable? Seems like it would be a trade-off between the larger sizes (better weatherproofing/longevity) and the smaller (going less into the sides of the valley, and deforming the sheets less).
I've seen EDPM washers size 14mm, 16mm and 19mm, so are they all OK, or is one type preferable? Seems like it would be a trade-off between the larger sizes (better weatherproofing/longevity) and the smaller (going less into the sides of the valley, and deforming the sheets less).
