Hi have recently had a new en-suite fitted , new tiles etc.
Everything is fine but I have a small crack in the grout right in the corner of the shower tray where the tiles meet the tray on the vertical. No other cracks have appeared. The floor is chipboard and then 6mm tile backer was placed to strengthen and reduce flexing. The tray was fixed using tile adhesive so I cant understand why it is cracking in just that one place?
Is the crack likely to let water through and if so, chall I just runa bead of silicone in the corner to prevent any leaking? Any advice appreciated.
I am not sure from your description where the crack is. I can't even make out if it is inside or outside the shower cubicle (if you have one).
Generally, gaps between different surfaces such as trays and tiles or windows and tiles should never be filled with grout as it will always crack. A flexible sealant such as silicone must be used. Even corners of stud walls can move enough to break the grout seal.
If there is a crack in the showering area that will get wet, then it will leak.
"Hi have recently had a new en-suite fitted , new tiles etc."
You may need to get your installer back - see below.
"but I have a small crack in the grout right in the corner of the shower tray where the tiles meet the tray on the vertical."
The tile / tray interface should have been siliconed not grouted. The corner (where tiled wall meets tiled wall) of the shower enclusore should also have been siliconed.
"The floor is chipboard and then 6mm tile backer was placed to strengthen and reduce flexing."
Ouch - you have movement. Chipboard is nowhere near stable enough and 6mm overlayment is not enough either.
"The tray was fixed using tile adhesive so I cant understand why it is cracking in just that one place?"
Acrylic tray or stoneresin? If the latter mostly the manufacturers instructions will say replace all boarding underneath with 25mm ply and bed tray on a bed of sand and cement mortar thus not only assisting you to get it nice and level but also ensuring that its supported across the whole area. I suppose tile adhesive could be used but the minimum spec would be of the flexible cementatious type. What adhesive was used?
"Is the crack likely to let water through......."
Yes and it will turn your chipboard into soggy weetabix eventually.
"....and if so, shall I just runa bead of silicone in the corner to prevent any leaking?"
You could but if I were you I'd be getting the installer back in to recify his mistakes seeing as how it was only done recently.
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