Vinyl stained within a year

[bullethead123]

Hi all,
I let out a flat and last year, while it was between tenancies, I gave it a makeover. One of the jobs I did myself was to freshen-up the bathroom, including laying a new sheet of vinyl.
I remember the concrete floor underneath the old vinyl being a little uneven so I leveled it with something (I think it may have been some kind of 'instant cement'. Anyhow, one year later the tenant tells me that this ugly stain appeared after her husband spilled water over the side of the bath.

Could this stain have been caused by inadequate preparation?
If so, will I need to take up the vinyl and treat the concrete floor before renewing the vinyl?
If so, what would I treat it with?
Could I just lay new vinyl on top of the stained vinyl?
If so would I need to treat the stained area with something?

Thanks in advance for any contributions,
Chris.

 

[JohnD]

looks to me like the floor has previously had glued-down tiles, and the glue was not properly cleaned off.

however, vinyl can also be stained by e.g. a leak when there is something standing on it, or magazines (the coloured ink can migrate). In that case, try cleaning it off. White spirit may work if detergents fail.

 

[bullethead123]

looks to me like the floor has previously had glued-down tiles, and the glue was not properly cleaned off.

Seems reasonable John. The marks look the size and shape of tiles. I guess I'll have to remove, clean, and replace with fresh vinyl. As to cleaning any old glue off, is there any solvent or method you would recommend?

 

[JohnD]

if it's glue, it seems to have penetrated into the vinyl from beneath. Some materials can diffuse into plastics or rubber, I don't know how. You see it on white PVC cable sheathing.

Maybe this
https://diy.evo-stik.co.uk/product/adhesive-cleaner

There are spray-on removers but I don't have experience of them.

Take a scraper, if you can soften it, it may scrape off. maybe some non-plastic impermeable layer like metal foil on the floor would block it.

 

[crazydaze]

Hard to know without seeing the subfloor but it's very common for vinyl to discolour from moisture underneath, could be poor prep/materials, could be moisture, could be a stain from above (less likely)