I am suffering (or should I say my kitchen ceiling is suffering) from this very common problem. I thought I had the shower completly watertight and had my ceiling re-done when Lo and Behold I noticed a small tell-tale watermark yesterday. I am now thinking of having the showertray replaced and resealed.Is there an advantage in putting in a porcelain tray, is it more durable? Has anybody any tips on the ultimate watertight shower and finally has anybody found a good plumber recently?