Freshly laid tile grout cracking

[dchur]

Hi team,

I grouted my wall splashback 24 hours ago and it looks like there are cracks all over it.

I used a pre-mix dunlop ultra white grout from bunnings. It did specify a maximum gap of 5mm,which most of the gaps between these tiles is. I'm really upset about this, and I'm not sure why it has happened and what I can do about it?

Do I need to rip out all the grout and do it again? This will take a whole day to do and I'm not even sure how you'd do it with this type of tile.

Is it a losing battle if I add some grout over the top of the cracked parts because it would just continue to crack?

It's a 1.5m by 50cm splashback that won't be exposed to any moisture.

[MitchellMc]

Hi @dchur,

I'm so sorry to hear you've experienced an issue while grouting.

I've sent your images to the Dunlop technical team for them to review. In the interim, could you please provide some details on your application technique and what tools you used to apply the grout? 

Many thanks.

Mitchell

[dchur]

Thanks @MitchellMc ,

The product specifically purchased was "Dunlop 1.5kg Ultra White Ready-To-Go Coloured Grout"

I used a grout float to apply the grout and followed the instructions to wipe off excess with a grout sponge and then buff/polish after it had dried about 10 hours later. Woke up this morning and saw the cracks 24 hours after the application.

Given that the cracks are mostly in the middle, I'm guessing the shrinkage is due to the 4-5mm gaps being at the upper limit of what this grout is capable of handling.

I'll wait to hear back but I'm hoping that simply applying new grout over these cracks will act as a measure to cover it up. Like I said, this isn't on the floor and won't get wet.

[MitchellMc]

5mm is well within the product's working limit, @dchur. Issues such as this can occur from substrate movement, not pushing the grout deep enough down into the joints, or the grout not being dry enough during cleanup and getting wiped out of the joints. What's the weather been like near you? If it's rainy, the grout might not have had enough time to dry, and if that's the case, it can be dragged out of the joint during the cleaning process.

The Dunlop team has contacted me, and unfortunately, they've advised that the grout needs to be raked out in order for another coat to be applied. At least 3-4mm would need to be removed so the new grout can adhere to the walls of the tiles and not just the cracked and compromised grout.

Given the amount of work it would take to remove the grout, it might be best to apply a thin coating over the cracked areas. I would mist the current grout with water so it's damp before applying the next coat. Even if the new coat fails, you won't be any worse off than having to remove it all.

Mitchell

[dchur]

Thanks Mitch.

We're in Sydney and yesterday it was relatively mild, not raining.

Yeah I can't see us raking all that grout out. Given the contours of the tiles it would be next to impossible to do in a timely manner even given the relatively small surface area of the job.

I'll give that a go. Hopefully that covers the cracks and we can move forward.

Is it worth doing it sooner rather than later, or letting this layer of grout fully cure for a day or two before applying a new one?

[MitchellMc]

I'd be inclined to do it sooner rather than later; hopefully, if it hasn't entirely cured yet, it might form a better bond @dchur.

Mitchell

[dchur]

Thanks @MitchellMc , looks like it is doing OK now that I've "patched" those areas that were cracking. I guess time will tell.

I do have another question about silicone but I'll start a new thread for that.