Need help with Mortar and Grout

[red-beard]

As many of you know, I'm having a pool installed. The Tile and Coping crew just can't seem to get it right, or maybe my expectations are too high.

I have a Flagstone coping and fairly standard tile. Four main problems:

#1. Flagstone: I keep finding "hollow" sounding areas in the flagstone. It appears to be separating in the interior, leading to the hollow sound. Is this normal, or am I getting bad flagstone?

#2. Hollow sounding tile. We ended up stripping the entire pool and redoing the tile. Still a few problems, but this is getting resolved. I think this was a serious installation problem. Can someone explain how it should be done so that air voids do not occur?

#3. The grouting in the tile has a lot of pinhole voids. I am guessing this is from too much air in the grout as it was being mixed. The tile repair crew came over and slather more grout on top to fill the pinholes. Is this the correct way to fix this?

#4. Several of mortar joints between the flagstones and some of the joint between the flagstones and the tile has cracked. Many of the flagstone joints, the crack follows the edge of one of the stones. It seems like the mortar didn't adhear to one of the stones. Is this "normal" or should I require these to be fixed?

I've been holding these guys to a pretty high standard. I just want to make sure I'm not being overly picky.

Thanks in advance.

[Zeke]

Man, I could go on this one for days, but I'll let everyone tell their advice. I'll just start with tile should not have a hollow sound once set. If necessary, each tile might have to be "back buttered" before setting into the grooved tile set. The more irregular the tile, the deeper the notches in the spreading trowel and the more need for the additional mortal on the back side of the tile.

To me, all of the answers are obvious. If they don't get explained overnight here, I'll weigh in again. Clues: too much water and not enough. Sorry, that's as far as i can go, I'm tired and my spelling corrections are taking more time thatn the message.

[trekkor]

There should be no hollow sounds...Ever!!

Hollow means no bond. It is being held together by the grout and still has the ability to move, leading to the cracks.

Flagstone is usually pretty dusty and needs to be washed before installation. Add mortar that is too dry and water mixed ( no acrylic ) and you will get a broken bond.

The grout should have no pin holes. If it is the grout below the water line tile you should request epoxy grout to avoid staining.


Go around the entire job knocking with your knuckle, looking for hollows and mark them with blue tape. Insist these pieces be reinstalled.

If you let it go, you will have to pay to have it repaired later.


KT

[red-beard]

Good, I'm glad I am not being overly picky.

The Hollow sound with the flagstone coping appears to be from the stone splitting in a horizontal plane, meaning I'll end up with two pieces the same size, but 1/2 the thickness. Most only sound hollow in one corner.

The good news, I'm down to 5 tiles or less that need to be replace, 1-2 dozen pin holes, 1/2 dozen areas of mortar that need replacing and maybe 2 flagstone hollow sounds.

OK, wash flagstone before installation. Is it OK (or better for that matter)for it to still be wet/damp when the grout is installed?

Last question: How much tool mark would you find acceptable? Some of the flagstone sides are nearly smooth, some show a little round saw cut and some show deep grooves.

[trekkor]

If the flagstone splits you may be able to set it back in place with epoxy.

The washed stone should be damp or dry. Dripping water will create a cushion effect and will seperate when the mortar is dry.

The mortar should be placed over the slab and on the backside of the stone. Wet mortar on wet mortar is the best bond.

As far as tool marks go, the whole concept of a flagstone patio is to produce a surface that appears to have fit together without any cuts.

They should be "dressing" the cut edges of the stone to disguise any marks.


KT

[Zeke]

I think KT has nailed it pretty good, so I'll not go on too much. Large pieces of flagstone are hard to set on a complete, solid bed. I have used regular brick mortar and made bullseye circles and wiggled the stone down to grade. There will be a few voids. I like to pour in a mixture of runny sanded grout or even fastset anchor cement around each stone and leave that low. Then the final grouting can go in. If you like, you can cut channels in the base mortar to let the runny grout flow under more to the center of each stone, but really that should be well taken care of with the base. What I'm trying to say is, I favor the center of the stone for the base mortar and backfill the edges with the runny stuff before grouting. The acrylic modified stuff KT mentions is really good for the finish mortar, but hard to clean off the stones. Lots of masons don't like to use it on unglazed material.

Your other point about the pin holes being a result of entrapped air sounds about right. And, maybe a little too thin. They could mix it slower and let it sit for a bit before using. Probably have to be re tempered, which is not so bad of an idea.

BTW, what are the weather conditions? Have anymore questions, come on back.

[red-beard]

Here are some pictures

[red-beard]

[red-beard]

Temp has been hot and humid. 92-95 F with Dewpoint around 70-75F

[red-beard]

Any more thoughts from the pictures?

[mattdavis11]

I wouldn't be very happy with that work. Is MMG the pool installer?

[trekkor]

Originally posted by red-beard
Any more thoughts from the pictures?

I would be flipping out by now...


The soft joint between the deck and the flagstone needs to be re-done.
It should be backfilled with sand and then the pourable joint filler applied on top. The material needs to be about 1/2" thick or so.

The saw marks on the edges of the stone make me mad
I'd suggest sanding them with 80 grit first and then using finer grit, maybe 400-600, or until you like the finish.

Use an orbital sander or better yet, a large variable speed disc grinder.

You should not have to see any saw marks...Unacceptable!!

Anywhere the grout is missing or there are holes, these need to removed and redone. Use a dremel with the carbide tile cutting bit.

I see a lot of blue tape


KT

[red-beard]

Originally posted by trekkor
I see a lot of blue tape

I didn't take a picture before the tile was redone. There was blue tape on every other tile.

[red-beard]

The joint between the coping and the deck hasn't been filled yet. They have a plastic material (looks like packing foam roll) to keep the concrete from the pool and the deck from joining.

[red-beard]

Originally posted by trekkor
The saw marks on the edges of the stone make me mad
I'd suggest sanding them with 80 grit first and then using finer grit, maybe 400-600, or until you like the finish.

Use an orbital sander or better yet, a large variable speed disc grinder.

Actually, I used an orbital sander on the hot tub on Sunday. I used 60 grit and the grit fell off the paper pretty quickly. It helped, but I went through 4 pieces of sand paper (1/4 sheets) and it still left quite a bit of the tool marks. They are quite deep.

Here is the after picture.



I have a belt sander and I'm seriously considering getting it out and buying a new belt. Is there any sandpaper designed for this kind of job?

Also look at this picture. Is this normal for flagstone to have this material flaking/spalling on top? Some of the stones are like this, and some are not.

[trekkor]

On the sandpaper, you will go through a lot of discs.

They make sanding discs that are made of resin with industrial grade diamonds in them. I have a complete set. 50 grit all the way to 3000 grit.
They are about $40 each and are used wet. You acn polish granite with them.

Just get a "contractor pack" of 80, 120, 240 and 400 grit papers.
Use the 80 grit until all the saw marks are gone. Then move to the next paper. 120 may be enough for you. You'll have to try a sample area.
The installers really should be handling this.

The splitting of the stone surface. I call it "shaling". Use a putty knife, margin trowel or a strong jet of water to clear the loose surfaces.

Your installer should have done that too.


KT

[red-beard]

Well, the owner of the Tile company reviewed the stone work and declares that:

Hollow stones are normal. All stone has voids. 1/2 of the stones they install are like that (That I do believe!).

Cracks in the mortar and separation of the mortar from the stone is normal.

They are definitely beating me done on this. I am tired of looking at a concrete hole in my backyard. My wife and I are discussing letting the mortar issues go, requiring an extended warranty. I will not budge on the tiles or the crappy looking edges to the coping.

What I'm thinking: In a year or 2, rip the coping out and replace with a matte finish granite and expoxy grout.

[jriera]

And that is exactly what the pool builder/contractor is hoping for ... for you to let it go!!! Standard Operating Procedure .. to bring the homeowner into submission.

Been there done that ... don't do it!!

Think about how much you are paying for that job, compare that to a car and make analogies, will that be acceptable in a car of that price range?

You have spend x years without a pool in the backyard, you can wait another month or so and have it 'right'.

Using the word lawyer once in a while worked fine in my case.

Originally posted by red-beard
Well, the owner of the Tile company reviewed the stone work and declares that:

Hollow stones are normal. All stone has voids. 1/2 of the stones they install are like that (That I do believe!).

Cracks in the mortar and separation of the mortar from the stone is normal.

They are definitely beating me done on this. I am tired of looking at a concrete hole in my backyard. My wife and I are discussing letting the mortar issues go, requiring an extended warranty. I will not budge on the tiles or the crappy looking edges to the coping.

What I'm thinking: In a year or 2, rip the coping out and replace with a matte finish granite and expoxy grout.

[David]

When I had my pool replastered, there were a few items I wanted fixed after they thought they were done. I withheld $400 until they fixed them. I never heard from them again .

Red-beard, it's tough on us engineers. Sometimes we just have to realize the world will never be perfect and just let it go .

[Rot 911]

No way in hell I would accept this! Call it shaling, flaking, anything you want, but I would not call it normal!