by Mark from Marmox »
Tue Sep 23, 2008 2:29 pm
It's very unlikely to get worse but neither can it be easily fixed. This is what happens when the sub-floor comprises more than one type of material - they expand and contract at different rates as the house gets hotter and colder and if whatever on top of it is firmly fixed, if there's no flexibility it will pull it apart.
The only way to fix this properly is to take have it all laid on one type of substrate or include an expansion joint between the two types of base. However, after a year, there's really not much chance of it worsening so you might as well just re-grout it. Can you remember whether the edge of a sheet of marmox lined up with the perimeter of this other type of wood? If you ever replace this, always try and overlap these areas.
Regarding the UFH; if it works then its un-damaged, if it doesn't then it is. Even if it’s damaged, the UFH will not be dangerous - it just won't work. However, there is such flexibility in these UFH cables that I think it would take an awful lot more than a hairline crack to break it.