How to repair floor tile grouting?

[lukec]

Hi all, I'm looking for some advice on grouting some floor tiles. 

Our main living room and walkways are covered in a 1200x200 tile running lenthways along our house and most of the grout in the main areas is chipped / broken out over time that I'm looking to clean up.

To put some context to the house, it is a 90's build that we recently purchased. The house is on a sloping plot and over the years there has been settling / subsidence to a minor extent which has lead to one side being a few cm lower then the other (due an engineers report on that in the near future). 

Back to the tiles, there are a number of them that are slightly loose and due to the length of them, they rock ever so slightly along that length. I imagine they've been in the house for quite a while and the intent eventually will be to replace all of them with wooden flooring or something of that nature, though that job could be as far as 5 years away. 

My questions are:

- Is there a quicker way of removing grout beyond using a grout saw. I have about 100sqm+ of grout to clean up (its all pretty old so if I do some, I should do all)

- for the areas that aren't that damaged, is it ok to just scrape the top off the grout so that when I put down new grout, the colour matches but I don't have to redo the entire depth of it, or is it safe to assume old grout is pretty loose so it'll be a mistake to do so

- I've done a test around a wobbly tile overnight and it holds firm once I've put the new grout down. Is it safe to assume this will hold or will it all come loose again in the near future. I'm really only looking to get a few years out of this job before it is all replaced. 

I've attached photos below

Typical tiles throughoutExample of raised tilesExample of chipped / missing grout

Any input would be great. 

Thanks

[Jason]

Hi @lukec,

Thanks for your question and for the thorough explanation. You might also want to share some photos so Workshop members can see what you are working with and provide more specific advice. 

Let me tag one of our resident Bunnings D.I.Y. experts in @EricL to assist as soon as he can. 

Jason

[lukec]

Thanks Jason for the reply - I've updated the original post with photos

[EricL · Accepted solution]

Hello @lukec

Congratulations on purchasing a new house, I suggest using a multitool in combination with a Diablo 70mm Multi-Function Tool Ultimate Grout And Mortar Blade. This will expedite the grout removal and allow you to repair the area much faster. Please make sure to wear gloves, eye protection and a dust mask when using this tool. 

Repairing the grout line is not enough to secure the tile to the floor. The tile must be cleaned off and the old adhesive on the floor must be removed so that you can re-attach the tile to the floor. If you are looking for a few years of extended service the tiles must be re-glued properly. Please note that if you don't have spare tiles, extreme care must be applied when removing the grout to prevent cracking the tiles.

I suggest using Dunlop 20kg Trade Resaflex it is a rubber-modified adhesive and is capable of absorbing substrate movement. So even if your floor moves the tiles will stay stuck to the floor. If the floor tile is still fully attached to the floor there is no need to remove it. I recommend mixing only what you need for the repair so that you'll not be wasting any adhesive. 

I don't recommend doing a half-and-half repair of the grout line as the new grout will not adhere to the old grout. If that happens all that hard work you just did will have to be repeated. I recommend removing all the grout so that you can be sure that it has been laid in properly with no chance of grout failure.   

Here are some handy step-by-step guides:

• How to remove grout
   
• How to mix grout
   
• How to grout wall tiles ( the techniques used are applicable to floor tiles )

If you need further assistance, please let us know.

Eric