Silicone tile junctions in a shower instead of grout?

Bit random but we have received a rather strange request from our site supervisor. I will quote in full so there is no misunderstanding.

Also to keep to building regulations minimum requirements you will

need to clean out the grout joints in the shower recess areas along the

wall/floor and wall /wall junctions as these must be siliconed also .

I can’t hand the house over without it being done .​

I challenged this because we have a full brick construction and I have never seen tile joints siliconed in a full brick construction. I also spoke to the Senior Building Survey at the local government who advised he is not aware of any such requirements. This is the response I got to my challenge.

Australian standards

Must be completed

Flat walls not reasonably expected to move but corners , particularly of different materials can be reasonably expected to move requiring a flexible joint at these joins .

We do this day in and day out , deal with building inspectors and all regulations from all governing bodies .

Every building company has to silicone Hess joins as specified .​

Attached to the email is Appendix A of AS3740-2010, Waterproofing of domestic wet areas. My understanding is that AS3740 determines the waterproofing that should be applied before tiles are installed. My understanding is that the relevant Australian Standard would be AS 3958.1-1991, Ceramic tiles Part 1: Guide to the installation of ceramic tiles. I don't have access to that Australian Standard, so I don't know if it specifies silicone in junctions where the tiles are installed over a rendered brick substrate but I would be very surprised if it does.

So, does anyone know if it is a requirements that tile junctions in showers must be siliconed and not grouted if the tiles are installed over a rendered brick substrate?

Help me @Westminster @pinkboy @Scott No Mates @Leo2413 You're my only hope!

 

For my brick wall house the corners (where two walls meet vertically as well as the perimeter of the base of the shower) were siliconed instead of grouted

 

Maybe this helps.


Minimum Waterproofing Requirements:
The Building Code of Australia (1996) and the Australian Standard (AS 3740-1994) "Waterproofing of Wet Areas in Residential Buildings" require that the following areas within a bathroom must be waterproofed:

• Full floor within the shower recess including down into the waste or if the shower is not enclosed, within 1.5 meters horizontally from a point vertically below the shower fitting
• If the shower is enclosed, minimum 100mm over the hob or step-down onto the bathroom floor
• If the shower is enclosed and exposed to a shower fitting to a height 1.8 meters above the floor or to a height no less than 150mm above the shower rose if it is within 75mm of the wall
• Immediately behind a bath, trough, sink or similar fixture
• The junction between the floor and wall of the shower; the junction between the wall and the fixture (the flange)
• The full bathroom floor if it is made from timber, plywood or particle board or is above the ground floor
• Tiled finishes over fibre reinforced cement sheeting or moisture resistant plasterboard provide an acceptable wet area lining except at the junction surfaces where additional precautions are necessary.
• A generous bead (10mm wide) of silicone should also be applied to:
• All wall/floor junctions within the shower
• Junctions between 2 wall sheets within the shower recess up to where the tiling finishes
• The perimeter of the waste outlet/floor junction
• The silicone should be smoothed over so that it extends 5mm either side of each junction.

Many councils now require that new waterproofing work be performed by licensed waterproofing applicators and a certificate be issued once it has been approved by a certifier.

 

Mine too and some of my IP's that were grouted, the grout cracked and partially fell out before getting siliconed.

 

In my experience (which is not from reading the standards but from what my tiler does) wherever tiles meet something and could be a potential point of friction/prone to losing grout a silicone is used.

These areas are
- join of bath to tiles
- joins of vertical and horizontal planes of tiling
- join of bench top to tiles

 

I have seen it done in a brick veneer house. The grout and silicone went manky and mouldy. I cleaned both the grout and silicone. The mould cleaned off the grout but not the silicone. The only way to have clean silicone is to remove and reinstate. I would not recommend it.

 

Does that apply before or after the tiles are installed?

 

I am living in a house that is 25 years old. The tiles are all grouted, no silicone. There are no cracks in the grout.

 

Interesting. I have seen silicone in [1] and [3] but not [2] in a shower. Does your new house have silicone in the corners of the shower?

 

I'm guessing after but tbh i just like seeing the toys go in. I don't pay too much attention to those things

 

Haha. Yeah. But then your builder has probably never told you to scrape out 15 metres of grout and replace it with silicone!

 

Cos I'm not crazy enough to do the tiling/grouting

 

• A generous bead (10mm wide) of silicone should also be applied to:
• All wall/floor junctions within the shower
• Junctions between 2 wall sheets within the shower recess up to where the tiling finishes
• The perimeter of the waste outlet/floor junction
• The silicone should be smoothed over so that it extends 5mm either side of each junction.

The wording seems to imply that it's after the tiling. Doesn't make sense to me to silicone before tiling on top of the waterproofing. It's pointless.

 

It was worth it. I just needed a site supervisor who is not an idiot.

Either:

1) it is a requirement of the Australian Standard, in which case it was his job to tell us before we did the grouting

or

2) it is not a requirement of the Australian Standard, in which case he is incompetent or being malicious.

Personally, I would not build with them again.

 

Silicone in the floor/wall and wall/wall joints as the builder asks for. Period.

pinkboy

 

Waterproofing is done before tiling commences because neither grout nor tiles are waterproof.

The silicone goes under tiles in junctions because those junctions are most likely to move/crack and silicone is flexible so maintains the waterproofing.

 

Is it though.. his job to tell you about it since you took responsibility for that part of the works..?

 

I'm not talking about waterproofing. I'm referring to using silicone after tiles are laid in the junctions, not before the tiles are laid. That was my understanding of it.

 

Is that a requirement of the Australian Standard or is it considered best practice?

The reason I ask is because the Building Surveyor who will issue the Occupancy permit doesn't think it is a requirement.

The other issue is that since the grout is already in place, there is a high probability that removing the grout will damage the waterproofing. The waterproofing will not be able to be repaired properly in a grout line. That will leave the shower at risk of water penetration if the grout is removed and replaced with silicone.

 

It is his job.