Cutting a hole in a ceiling (builderstrackworld!)

Supremebean/ Dave – we will have to agree to disagree. Despite being marketed as such, this usage is not what sealant is for, and it is only ever a temporary fix. Using it horizontally to maintain watertightness at the exposed junction of tray and wall tiles is crazy. Why do you think people have so much trouble with leaky showers and black sealant? Bad installation using unsuitable methods, materials and junctions. The only reason it is so widely used is because people have come to see this as the norm, and it is the easiest and cheapest way of doing things. But after a while it will always fail. The enclosing walls and panels should be finished with a proper drip channel which directs all water into the tray. It’s a bit like kitchen worktops, proper worktops have a splashback as part of the actual worktop with no exposed junction that can allow water ingress.

Check the tile grouting for cracks. Water can seep behind the tiles and track down.

andy kirk , can you send a link to the coram mira units that say not to use silicone .
proper worktops with splash back ? i am assuming you are talking about the small up stand, that also will need to be sealed as water can ingress in and damage wood.
out of interest how do you suggest you finnish of internal corners in shower where tile meets tile, or where tile meets shower tray ?..

Dave – have a look at this page for Kinedo showers – the right hand side explains the general idea.

http://www.kinedo.co.uk/why-kinedo/

To answer your query about how to finish such a junction, well, you are forced to use sealant aren’t you. What am I saying is that the whole wall tile/ shower tray junction is daft in the first place.

Yes I am talking about worktops (not timber) with upstands that are integral to the worktop. They don’t need sealant as the upstand is part of the worktop and therefore there is no join. I guarantee most ‘modern’ kitchens will have dirty rotting failing sealant behind kitchen sink areas.

As an aside I once had a meeting with one of the managers from Poggenpohl. I was involved in kitchen installations in a large supposedly high-end residential building, and the developer wanted to put in granite worktops, which we advised him against as they are really not up to the job. Off the record, I asked the Poggenpohl chap what the best material was for worktops. In a very quiet voice he said ‘vinyl, but don’t tell anyone’.

Why do you think people have so much trouble with leaky showers and black sealant?

I remove and refit 35-40 bathrooms per year. Pretty much every time the showers have been leaking the problem was as bear said further up the thread, especially in new builds. I have removed plenty of showers that have been fitted for 20+ years which have never leaked and have reasonably clean silicone. There’s no point trying to convince me as i have seen the evidence myself that properly applied (tooled with no water or finger involved) silicon will stand the test of time.

Top Causes for silicone going black and silicon failures? Tradesman licking his finger (introducing bacteria, most common problem) and using saliva to smooth out silicone bead. Cheap non anti-bacterial silicone. Applying to wet or dirty surface. Homeowner not cleaning silicone enough. Movement in shower tray because lack of bedding and not being sealed to wall before tiling.

Again, those showers in that link are bloody ugly. I can imagine their main customer base are pensioners, nursing homes and building companies that have had lots of problems in the past with their shower installations because they can’t do them right. I get local building companies emailing me regularly asking me to do their showers for them because their tradesmen don’t know how to do a proper install. There is a sequence in which it all has to be done, any part of that sequence missing it will most likely fail. The problem with new builds is there may be 3 or 4 guys involved in that sequence.

I always tell my customers to call me if any problems with silicon.
Never had a call back yet in 12yrs SE, and have revisited a few as i’m a plumber to trade so also do general plumbing and heating for my customers.