Like the thread title says - can you put neew grout over old?

I just tiled and grouted a shower a few days ago. In final cleanup I noticed a couple areas where the grout appears chunky, maybe even pinholed. Somehow I must have missed this when grouting, and now I want to fill it. But will it stick?

Also, I'd like to apply grout over the existing grout on the floor - it is a little darker and discolored due to age - but again the question remains, will it stick?

Thanks in advance!

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yes..

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You can certainly apply new grout over old, but, generally, the grout needs to have something to grip. A very thin surface treatment is not likely to hold up for the long term.

When I do a regrout, I use one of those small carbide grout saws to scrape out as much grout as possible. Then, the replacement grout is of a decent thickness and will have a chance at surviving without chipping off.

Thanks for reminding me of yet another chore I need to do at home . . .

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you can reaply over the old, however, by the time u are either retiling or replacing, the grout is likely in need of change anyways

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Read about cleaning grout with acid. You can probably make it look new again where it is not damaged.

Yup. Imagine spreading a thin sheet of concrete (minus the rocks) over existing concrete, say 1/16 inch thick. It would break apart very easily when cured. It's nice to have a 1/4 inch or so thickness. When I'm laying tile, I always scoop out the thinset from between the tiles so my grout will be thick.

But as far as patching a few spots on a recently done job, might work.

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