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How to fix flakey grout and effervescence on tiled porch edge?

workerbee

My front porch was tiled a couple of years ago, the tiler recommended using Ardex grout on the vertical sides of my porch. I’ve noticed this winter, due to being exposed to the weather. this front grout face is starting to flake off in places where the white mineral residue is forming and started to expose the edge of the tile which I am worried about given we are in the midst of winter. Any advice would be greatly appreciated, thank you
Photo attached

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MitchellMc

Welcome to the Bunnings Workshop community @workerbee. It's great to have you join us and many thanks for your questions about grout.

From your photo, it appears the grout applied to the face of the porch is quite thin, and that's likely contributing to the issue. Grout performs best when it's installed between two substrates, such as between adjacent tiles, where it is locked into place. It generally doesn't perform particularly well when applied as a thin layer over a flat vertical surface like this.

I suspect a combination of the minimal grout thickness and water ingress over time has caused the grout to deteriorate and spall away, with the white residue you're seeing being efflorescence caused by moisture moving through the substrate.

In situations like this, the best long-term solution is typically to remove the loose grout and tile the front face of the porch using a quality tile adhesive. This will provide a much more durable finish while also protecting the exposed edges of the porch tiles. Once the face tiles are installed, the joints can then be grouted as intended, with the grout locked securely between the tiles rather than acting as a surface coating.

You could try re-coating with the Ardex grout, though you'd like find it requires bi-yearly touch-ups.

Let me mention @Nailbag and @TedBear to see if they have any other thoughts or alternative suggestions.

Please let me know if you have any questions.

Mitchell

Nailbag

Hi @workerbee

I can't offer any more advice other than what @MitchellMc has already provided. However, once you have repaired and re-grouted I would look to apply a suitable clear epoxy protective sealant over that front fall.

Nailbag

workerbee

Thanks for your replies. I am not sure if tiling would be viable as it’s quite a thick tile and suspect would have exposed edge on top where they join up as there is no overhang. If I did regrout could it be sealed or painted over to help protect more? Otherwise would I need to remove all the grout and then paint with an external textured paint perhaps?

JacobZ

Hi @workerbee,

If you tiled, you would use a tile trim like this https://www.bunnings.com.au/qep-12mm-x-2-5m-silver-mosaic-tile-trim_p6650278 where the box section is the same thickness as your tile. This will give you a much cleaner corner finish and would mean the slab edge is not exposed.

Grout is not typically used like this. As Mitchell mentioned, it is usually applied between things like tiles, in narrow applications less than 15mm wide. It is not designed to be plastered over a wide, flat surface like this and in the long run will almost certainly crack and flake off regardless of what you apply over it.

If you were not going to tile the slab edge, you would be much better off removing the grout, sealing the slab edge with a primer then applying a render or textured paint, ensuring you follow the preparation and application recommendations for the specific product you use.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

workerbee

Thanks Jacob, yes I think I will try the paint idea and check out what you have in a smaller tin. Appreciate any tips on how to remove the grout, I have 2 sides to do and can take my time with it.

JacobZ

Hi @workerbee,

You should be able to remove it fairly easily by breaking it up with a hammer and then using a scraper tool such as this https://www.bunnings.com.au/trojan-6-in-1-multi-paint-scraper_p0093215 to remove it once it has fractured.

You could also use, an angle grinder with a wire wheel, as long as you wear your personal protective equipment including long protective clothing, ear and eye protection and a mask.

Let me know what you think and if you have any further questions, please don't hesitate to ask.

Jacob

workerbee

Thanks Jacob, I might just try a concrete sealer coloured paint first once I fix up that small section of grout. The rest of it is in good condition and I’m not confident doing much else,

But thank you all for your help and advice, it is greatly appreciated

Regards Susan