Hi I live in a new build and we are the first owners and have had it now for 2 years so we are on decorating. I have just painted my hallway ceiling but when its dried there is a water mark type stain now on the ceiling. This wasn't there before I painted so just wondering why this could have happened and how to get around it as just painting over the top of it, it still seems to show through. What is confusing me is that it wasn't there before I started painting so why wont it disappear under the new coats of paint.
You need to see if there is a leak anywhere first. Check to make sure. If none then buy some stain block and put that over it first before emulsionanning again.