Some grouting done using Silicone rather than grout in a shower

ashe

We had our tiny en suite done recently and its looking great, but it was a tough job to get done. The original en suite had a 700x700 tray and a row of tile which was wasted space, the new tray is 900x800 fits the space. The builder who put it in for us (who also did our downstairs toilet which we are happy with), came across the fact that the internal walls were made of straw, known as Stramit board. He said it was a nightmare to work with as it expands when channelling out etc. 

Anyways, suite is in, looks great, but we got a small leak downstairs. We checked measurements and worked out its right below the wall of the en suite, and when we look at the bottom row of tile, one of the tiles is sticking out and the grout is cracked, so we let him know as he stands by his work and came out to sort it out. He took the tile off and the Stramit board behind it had gotten wet which caused it to expand and push the tile forward. He said this is his error as its at the line where the old shower tray was, and as the new one sits lower down, he hadn't put enough adhesive in and somehow water had gotten in which caused the stramit board to expand, or something to that effect. He has coated the stramit board in a sealing product and applied something else that he got told about (EB25 sealant) as that can be applied on damp surfaces (we ran the dehumidifier for 24 hours and he took out all the damp material yesterday) and has replaced the tile. 

He's then said today that instead of grouting the parts that he had taken the grout out of, he has used a colour matched sealant from the same brand (Mapei Mapesil). The colour is close as its same brand, and the tile is low down so you'd only really see it if getting up close, but I'm concerned that in my limited experience of sealants, whilst they do allow some movement, they eventually lift away so feel like in a few years we would have to get it redone?

Guessing its just something we will have to suck up due to our unusual wall construction, but wondered if this is likely to cause us any problems down the line or if its the best course of action?

SaverRate

Why wasnt the stramit board removed completely from the bathroom?

andyhop

Completely unsuitable product for tiling onto. Should have been removed 

ashe

andyhop said:

Completely unsuitable product for tiling onto. Should have been removed 

It must take tiles ok because there are two layers of tiles in the master bathroom with a pvc panel laid on top of that and none of those 3 layers seem to have failed

HarryDavies01 said:

Why wasnt the stramit board removed completely from the bathroom?

Because there would then be no walls in our hall, main bedroom and my office because it's a complete wall solution, and those rooms are recently decorated so we'd need to rebuild all walls on both sides and redecorate on top of that

fenwick458

silicone for one tile is fine, nothing to worry about. 
nothing compared to having walls made of straw in a bathroom

NSG666

I live in a house with straw walls and for about 18 years had a daily used tiled shower enclosure against one of them and it was fine. I did have a leak from the CWS tank in the loft that got into a wall and caused it to swell up so I do know what water can do to it. For other reasons I changed it to a metal stud wall but because I'd seen how it can swell if I'd retained it I'd either have tanked it or stuck 6mm tile backer board on it especially if tiling with the currently 'on-trend' public toilet tiles.

ashe

I think he did use a backer board, there is a layer of plaster skim over the straw too. 

It's waterproof now as been used with no additional leaking but he has proactively said that he doesn't like the mastic solution and is going to take it out and regrout it once the main bath is done 

thanks all

rob7475

that's a good result. Sounds like you've got a good tradesman there.

It's always good to hear the outcomes of these threads too