Why has the shower sealant in both my new bathrooms got black mildew growing on it already

[whoneedssleepanyway]

Had both my bathrooms completely redone in the last 18 months and already the sealant round the edge of the shower tray in both bathrooms has black mildew growing on it. Can't seem to shift this with any cleaning products (scrubbed like mad with an old toothbrush) and google seems to indicate that once this is in there is no shfiting it and the only solution is to cut out the exisiting sealant and redo it.

Why has this happened, the bathrooms are cleaned regularly, there is no mould growing anywhere else (e.g. on bath sealant or round sink).

Is this an easy job I can do myself and if so how do I prevent the problem from returning?

Thanks

Was the wall behind waterproofed properly before tiling?

Could be that the sealant wasn't applied correctly too. We have had this problem, and many others, which have slowly shown the person who fitted our shower to be incompetent!

what is the ventilation like in the rooms?

Mould and mildew remover worked to remove the mould each time it appeared.

Thanks. V reputable builder did the job, all other work he has done for us has been good, but will have to check with him re waterproofing the wall.

Ventilation have windows and fan, in one bathroom the fan goes on as soon as you switch the light on, in the other it is a separate switch so prob isn't used as much as should be.

Will have to look for mould and mildew remover have been using normal cleaning products but it feels like it is ingrained if you know what i mean....

HG bathroom spray from Lakeland is the best mould/mildew remover I have come across. It was highly recommended on another thread.

I always squeegy walls and doors after a shower and leave the shower door open afterwards.

my builder reckons this is because when the plumber seals round the bath, tray or whatever, he/she licks their thumb and runs it round to scrape off the excess, instead of using the proper tool

(mind you, he's a terrible bullshitter. He once told me that the most dangerous everyday item in the house is SOCKS, because idiots in a hurry put their socks on on the stairs and then fall over)

I take no chances since this happened to me

every bath/shower, the last person has to wipe it down with a dry cloth and then leave doors etc open. It's a pita, but seems to be working

As our shower needs ripping out due to being made so badly and becoming unmanageably mouldy we are now turning out bath into a bath/ shower.

After much research we learned we needed to put a primer on the wall and then two coats of waterproof stuff as well. The waterproof coats each needed over 10 hours to dry so you should have seen if your builder had used it as he would have had to leave and come back a couple of times and you would have seen the sluggish grey colour on the walls before tiling.

I'm no expert though and there may be some other way to waterproof.