Not exactly roofing, but I can't think of anywhere better to post this... There’s a 110mm soil pipe running almost horizontally just above a window. On the window sill beneath there’s a window box. When it rains, water falls from the bottom of the soil pipe onto the soil in the window box and splashes and makes a mess. What I’m thinking of doing is fixing a sloping strip immediately under the soil pipe, the width of the window, that would project just beyond the window box and so throw off the water onto the ground beyond. Sort of like a mini-porch. Is there a better idea? And if I did this, where would I get the strip? It would measure something like 130cm x 20cm and I guess might be pvc.