Water Line Tile Restoration

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mknauss

mknauss

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TFP Expert
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May 3, 2014
62,659
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
We have a fiberglass pool, 10 years old, with waterline tile using cement-based grout. Pictures below.

The issue is that about 40% of the grout has failed. Some I have replaced over the last several years with silicone grout (Novagard) – the picture with the tan/brown grout below. I am contemplating several paths to replace/repair what we have.

The first path would be to remove it all. Replace the tile with new and regrout the entire thing with silicone grout. I am not sure I wish to tackle that and finding anyone locally I would trust to do that is not likely.

Second path is to remove all the existing grout, even that which not compromised, and replace with NovaFlex silicone grout. Some of the tiles are loose and will be reapplied using marine grade silicone adhesive. This would allow for the grout to match throughout but is more work.

The third path is to remove the comprised grout but leave that which is stable. Matching the grout color will not be perfect using the Novaflex, but it will reduce the volume of work significantly. I am of course leaning towards this path.

I am looking for advice on the viability of removing the grout. I plan to get an oscillating tool and use a grout blade to remove the grout. The small amount of existing silicone grout will be removed with a cutter, etc. Does anyone have experience removing grout with this method? The application of the silicone grout (Novaflex) I feel comfortable with. I will use scrub pads recommended by Novagard.

The pool will be fully drained for this project. It is time to do an iron removal (our Colorado River water has small amounts of iron and after 4 years of not draining it is showing on the walls) and the CH has climbed even with the use of an RV water softener for the fill water. We evaporate about 2.5 pool volumes a year so 4 years of not draining is astounding. Draining a fiberglass pool in our area is of no concern.

I will likely not use all 24 tubes of grout I have to buy (direct from manufacturer – not available retail anywhere I can find) so I will update this thread when done on what it looks like and how much I have left if anyone is interested.

Non Compromised Cement Grout
Tile3.JPG
Compromised Cement Grout

Tile5.JPG
Tile8.JPG
Novagard Silicone Grout used for Repair several years ago
Tile6.JPG
 
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mknauss said:
The third path is to remove the comprised grout but leave that which is stable. Matching the grout color will not be perfect using the Novaflex, but it will reduce the volume of work significantly. I am of course leaning towards this path.
Click to expand...
Since you mentioned that you have used cement based and silicon based grout, you will need to identify this areas accurately and decide which is less work or looks better. Is there fiberglass behind the tile?

Im still a fan of Latticret Spektra-Loc epoxy based grout. Almost 5 years and no single tile or grout has failed. I will post a pic when i get home. Im a DIY, do it right the first time or dont do it at all, type of guy. So i will vote for removing the whole enchilada!
 
The original install by the pool company was cement based. I tried to get them to use silicone, but they said they did not know how to use it. Big mistake.

It is a fiberglass pool so the tile is adhered to the pool with silicone adhesive. I will actually be using the silicone 'grout' as an adhesive for the loose tiles.

If I could import your labor quality I would hire it out and replace it all. But in our rural area, that is not a good prospect.
 
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I have used an oscillating tool (Dewalt) on shower grout. While it does work, it is a A LOT of labor. You’re going to get sore arms doing it. You might investigate using a small angle grinder with the right blade for the job. However, that said, tile can be easily damaged by any mechanical grinding method.

Are you draining and bracing the pool shell? This kind of work is a lot easier to do when a pool is drained and you can setup some small scaffolding ladders.
 
I figured it would be some work with the oscillating tool. I can do an hour or so a day for a week or more and should be able to complete it. Especially if I only do the compromised grout joints.

No need to brace the pool that I see. I will have the pool drained while doing it. As you know ground water is of no concern and our earth is decomposed granite so it is surprisingly stable. Pool is also not all that deep so should have no need for ladders or scaffolding.
 
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Flying Tivo said:
I think a hammer drill chissel at a very low angle would do a better job than an occilating tool.
Click to expand...
I will look into that. Everything I have researched for grout removal was using an oscillating tool or using a manual grout knife. I believe a large amount of what I have to remove will come off with the grout knife.
 
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Give the oscillating tool a try. As long as it has the ability to do adjustable speed you’ll find the sweet spot that gives you a good cut with minimal force. You don’t need to remove all the grout down to the shell either, just get out the loose stuff and then put a new layer on that.
 
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The grout is only as thick as the tile. So 1/8" wide and about 3/16" deep.

As I said above, might be successful with them manual grout knife. But will get an oscillating tool at Harbor Freight (Variable speed) just in case.
 
I have removed grout lines on my pool using a grout blade in a Milwaukee oscillating tool. One of the things I learned is there are many different shaped grout blades available and some work better then others depending on the angles you need to get into.

Also some are much more heavy duty and stay sharp longer then some that dull out quickly.

I would be concerned about nicking the fiberglass with the grout blade. Digging in too deep or the blade slipping was not a problem for me hitting the gunite.

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Thanks Allen. I was hoping to get one of the half circle grout blades. I will have to limit the depth I go so to not get into the fiberglass.
 
Does your tile and grout line butt up against coping stones?

If so, the half circle blade will not easily get into the grout line against the coping stone as it will hit the coping. That is where a straight blade can plunge in. Consider buying at least two different shape blades.
 
I do not plan to remove the grout line that butts up against the coping. That would add alot of work and not sure we can make that look very good. The grout at the coping is not compromised.
 
After doing a tiled walk in shower, I can definitely echo @ajw22 ‘s suggestions - you definitely will need a few different blade styles. Semicircular blades are good for long straight runs. Squared blades are better for plunge cuts. You just don’t know what works better until you get into it.
 
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Last spring I “fixed” all my waterline grout; in my DIY install 10 years ago I left them slightly too deep and the recessed grout areas were “catching” small seeds/leaves/debris from my pool skimmer swirl. I used a small angle grinder and these diamond cutting blades to “extract” the old grout, like @JoyfulNoise suggested. It was easy to control and fast, fast, fast! It took me less than an hour. Depending on how wide your lines are, this method could be used to take out the majority of the grout and then use an oscillating/hand tool to clean the rest.

The key will be grout line width…some of mine were really narrow. Hard to tell from your pictures how tight those grout lines are, but this blade will not fit into all those lines, especially the tight ones. In fact, I doubt you will even be able to successfully extract some of those lower horizontal grout lines at all (not that you need to), short of removing the tile. But those lines still look pretty good and I suspect your plan is the best given that you can’t remove all the grout anyway.

In any case, I think they sell these blades at Home Depot/Lowes too (you would definitely not need a 2-pack)…a thinner blade would be even better but I couldn’t find one. I’m with TIVO on the laticrete grout, but it is really hard to work with and you might have to extract ALL the grout, including coping, to match.

 
The prep work is done. All the grout that was compromised (plus some that was not but was on the first grout line above water line) has been removed. About 50 tiles (2"x2") also were removed as they were loose. The oscillating/multi tool worked well. No real issues. Took me 4 - 2 hour days to prep everything. Three grout blades (2 different styles).

So next step is to use the Novagard NovaFlex silicone tile grout / adhesive to reattach the tiles and seal around all the shell penetrations (returns, main drains, etc). I cleaned the old silicone out from those as it had started to fail.

Hope to finish up over the next week to 10 days. Get the pool filled back up and balanced before we head out on our next cruise in mid December.

Take care. Will post some pictures of the final outcome.
 
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