How to repair grout gaps prior to laying vinyl tiles?

[kimbaday]

Hi Bunnings Team.
I asked this question at the special orders desk today and they said yes, but I want to double check. I need to fill in the grout in my bathroom and possibly the rest of my house (I may only do the bathroom) before laying my Gerflor Senso adhesive vinyl tiles and was told I could use the  Gripset Betta Concrete crack filler. It seems to go on perfectly and is so easy to apply because it has the spout and you just squeeze it into the grout gap, leave it for a bit and then smooth it over. I tested a small patch this afternoon (pic attached) - it has dried and filled the grout fairly well but it feels rubbery and is easily peeled off. I am concerned that it it is not the best filler for this project but would love your advice please. Is it safe to use under the adhesive tiles as a filler? Has anyone else used it?  The bottle says you can use it before laying tiles but nothing about adhesive tiles. To be fair I only used a small amount and I didn’t cegrease the section, I just cleaned it a bit and popped it on. Thank you so much for your help. 

[EricL]

Hello @kimbaday 

Thanks for sharing your question about Gripset Betta 1L Concrete Crack Filler. It does say that it can be used to fill cracks before you lay over vinyl tiles, but I don't think they were referring to large tile gaps. I don't recommend using it in this particular project. 

In this instance, I suggest using Dunlop 800g Ready-To-Go Coloured Grout - Slate Grey to overfill the grout line and flattening it with a trowel. You'll get a solid filler that dries off solid and will not be soft or flexible.

Please keep in mind that the surface of the old grout must be scuffed and cleaned in order for the new grout to anchor properly to the surface of the old grout. I also suggest having a look at these discussions - D.I.Y. flooring using adhesive vinyl over tiles by @diy_hausdesigns and Apartment makeover using paint and vinyl flooring by @RenoRach1. These members have done exactly what you are planning to do, it would be worth a peek to see how they did it.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[Dave-1]

Morning @kimbaday 

Since wandering through these pages I have flipped on the Gerflor Senso adhesive vinyl tiles. I went from a no to a yeah they look pretty good

One thing that has constantly turned up is a level floor, filling the grout level is not something I have done and the method @EricL has mentioned is the way id go as well. 

Installing the Gerflor Senso adhesive vinyl tiles over masonite might be an alternative. It will give a smooth surface where you wont need to worry about the dips between tiles. My mum has had this done with the stick down tiles from Bunnings for her kitchen and they have not lifted and the floor feels smooth.

Depending on the type of Gerflor Senso tiles you can get away with your tiles as is. I just had a wander over to their website and had a look. Can you lay a PVC floor on top of ceramic tiles?  its about 1/4 down the page and there are 2 paragrahs that suggest a rigid floor tile. Maybe thats an option to consider and then you wont need to worry about the gap bewteen tiles?

Dave