WIde joint grout - powdery

[hn101]

Hello, I have been repairing a shower which is as follows: raised wooden base with 15mm plywood floor for shower (no tray) covered in porcelain floor tiles 25cm square. The cowboy who originally installed it had some of the floor tiles sloping away from the waste causing water to sit in the corner and eventually after about 6 months the silicone would fail and start to leak. I decided to fix the problem by lifting the incorrectly sloping tiles and refix using BAL fast flex so they all now slope the right way. I didn't have time to finish it myself so called a tiler in to clean off the excess adhesive and grout them. I left a bottle of GT1 admixture and BAL wide joint grout powder for him. When I got back 3 days later I found that he did not use the admix. Not only that but the grout is very powdery and can be scraped away with your finger nail. Even without the admix I expected that the grout should be hard after 3days as it is totally dry. I don't want the shower to leak again nor do I want water to be absorbed too much into the plywood below, so i'm planning to scrape the old grout out and re do it carefully measuring the right quantities.

Could someone tell me why the grout the tiler put in is so powdery and whether I should re do it with BAL WJG. Is it going to be robust enough for the shower or should I use something else e.g. epoxy.(this is my first time tiling) Thanks. Do you think he deserves paying?

[GazTech]

Can't think why the grout is still powdery, if mixed with water it will chemically set. GT1 polymer should be added when onto plywood, to make it flexi.....as regards paying him, it's your call.......Gaz

[Dave]

The powdery grout could be a number of things....

1. Too wet a mix resulting in weak cement to water ratio....

2. Too dry not enough water to create a strong set.....

I think your biggest problem though is you have a wetroom type floor with no tanking of any sorts......

So even if he had used the GT1 admix water would have still ingressed through the joints.....

I think you have 2 options really.....

1. Pull the floor up and water proof it ( tank ).

2. Remove the existing grout and re-grout with epoxy grout........this will provide a water proof joint.......

let us know which way you go.......

[hn101]

I grouted a test area with the BAL WJG mixed with GT1 carefully weighed out and measured. A couple of days on it was still not hard i.e. a screwdriver would easily squash into it almost like pressing into biscuit (not really that bad but you get the idea). I think there could be something wrong with that bag of grout. 2 weeks on it was still not hard as grout should be. As I needed it repaired fast I bought MAPEI ultracolor plus for only £3. The literature states swimming pools can be filled after 48 hours rather than the 2/3 weeks stated on BAL WJG. The grout went off so quick I barely had time to get it done! I left it 4 days just to be sure it was cured and treated it with HG waterproofing grout sealer to improve it's water resistance. I intend to completely replace the bathroom in a couple of years so it should be OK till then. Will probably use MAPEI in future. Thanks for your help.

[Dave]

Thanks for letting us know how it went.......at least it is sorted now.......Good old mapei to the rescue.......

[Branty]

Without it being tanked, the plywood shower floor won't last 2 years. If the subfloor dosent fall to the drain you'll have issue of water sitting on the ply, and soaking through to the room below.