shamrock72

hi daywalker ive only seen this happen for 2 reasons..not using flexable floor grout. too much bounce on the floor causing cracks ,ply not screwed down securly.. or just as simple as the grout was gone off .when fully dry it would power like and easy to get out...would suggest new grout if if movement on the floor is not the prob. add pva to your new grout to give it more flexability small areas at a time it will dry very fast..hope this helps