Kitchen Floor Grout Attempt #2 [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-13-2019, 01:13 PM

First time poster here, looking for some advice on what to do to my 210 sq.ft. kitchen floor. The long and short of it is that I'm replacing the grout in a new floor that was put down about a year and a half back since it cracked. I've since removed the old grout and I'm getting ready to redo it. I'm looking for advice/suggestions on what type of grout I should use to prevent this from happening again.

The Long Story:
When I bought the house I noticed that a fair amount of the grout on the existing floor was cracked and/or missing from the joints. The entire kitchen was being gutted and remodeled so I removed the old tile floor. The sub floor included the original 1/2" thick plywood (nailed to the joists) with an extra piece of 1/2" plywood over that that was nailed too. The new floor tile is a 12"x24" porcelain tile and was put down by my father using some Ditra underlayment. I then proceeded to grout the kitchen myself using what I remember was Mapei Sanded Cement Grout. The 1st third of the kitchen went okay, but when I did the remaining 2/3's I messed up on the mix ratio (I put too much water). However, I was able to make it work and look right so I proceeded to finish the rest of the kitchen. About 4 months after it was all said and done I started noticing cracks in the grout of the new floor. From there it progressively got worst to the point where when I vacuumed the floor a few pieces of grout went missing.

Seeing as this was a brand new kitchen I decided to remove the grout and redo it all as it would only get worst with time. I used an osculating tool to remove the bulk of the grout and the rest with a utility knife (I went through at least two dozen blades here and one knife). FYI this was a horrible job that I'd never want to do again. To strengthen the floor I added some strapping to the underside which seems to have taken out some of the creeks I was hearing before as well as some bounce.

I'm now ready for regrouting the floor and want to pick the right product. I don't want to have a repeat of my previous results so I'm likely going to get a professional to do it. In order to prevent cracking, it was suggested that I use Epoxy or Urethane grout as they are stronger than the cemented grout used previously.

If anybody has some advice for me in regards to a choice of grout that would be great!

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03-13-2019, 02:28 PM
In my experience, grout rarely fails, but rather something else caused it to fail.

Have you checked your floor structure with the Deflecto tool in blue band above?

And on the levity side of things, I swear my 'nads twitched when I read "osculating". It sounds so, um, uh, well, sinister!
Also, I'm guessing that "creeks I was hearing" would be better described as creaks. Babbling brooks may be soothing, but not so much when coming from floor of house.

03-13-2019, 02:39 PM
Like mentioned it sounds more like a structural issue. If you only have 1/2" over another layer of 1/2" that may be part of the issue. Deflection may be another, enter your info and let us know what numbers you come up with. Having the correct subfloor and following the proper fastener schedule are crucial parts to having a successful installation.

03-13-2019, 02:40 PM
I knew I should have put that through a spell check first, oscillating! :think:
And yes, creak (sound) vs. flowing water lol

Looks like my floor fails the Deflecto tool test above :dunce:

The house was built in the 1970's, I know that per current building code span tables the house would not meet them. I was hoping that with the Ditra my chances of success would have been good, I guess not. I have since added some 1x3 strapping, I might have to look at bridging or adding a beam to help support things under there.

03-13-2019, 02:41 PM
Looks like I'm getting the following score:

For joists that are SYP or Douglas Fir, in good condition, 7.25 inches tall, 1.5 inches wide, 16 inches on center, and 12 feet long between supports, the deflection calculated is 0.478 inches.

This translates to a deflection of L / 302.

Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Sheet Vinyl or wood.

I'm going to double check what's existing for structure, I'm just going off of memory right now.

03-13-2019, 04:32 PM
Steph, that "1x3 strapping, which I'm interpreting to mean cross-bracing, does nothing at all to change the design deflection of your joists. The support beam certainly would, though.

Another problem you have is that neither layer of subflooring has T&G edges and I'll wager you have no blocking of any kind under the between-joist joints.

And your spell check wouldn't have helped with either of the words Peter mentioned, both being correct spellings, just not for the words you wanted. I, too, wondered about the creeks. I've built some pretty neat houses in my time, but never one with creeks in the living area. Wanted to once, but customer decided I'd pointed out too many negatives. Really would like to have done that. Ol' Frank Lloyd woulda been proud of me. :)

03-13-2019, 07:54 PM
I double checked the floors construction, my spans are closer to 11'. However, they're likely constructed out of pine rather than fir. The plywood isn't T&G and there is no bridging between the joists either. Here's what I'm getting from the calculator.

For joists that are Unknown wood, but in good condition, 7.25 inches tall, 1.5 inches wide, 16 inches on center, and 11 feet long between supports, the deflection calculated is 0.457 inches.

This translates to a deflection of L / 289.

Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Sheet Vinyl or wood.

The kitchen is 10' x 20', I've attached the floor plan of it. I've also attached some pictures of the floor tile used (300mm x 600mm).

At this point should I just go ahead and add a beam under the kitchen area in order to support the tile floor? I don't think I want to go ahead and remove the tiles and replace them with wood flooring. Would there be some other way of strengthening the floor and using a different type of grout that could endure some movement? I have access to cement, epoxy, and urethane grout so that's not really a problem.

A co-worker of mine has a stream running through his house, that's pretty close to a creek? I guess that's why you don't build on bedrock at the bottom of a mountain.

Thanks for all the help guys!

03-13-2019, 09:01 PM
Adding a support wall underneath to cut down the span would be a good start. Unfortunately that only takes care of the joist deflection and doesn't do anything for the between joist deflection of the subfloor. Hard to say whether it will be enough to keep your grout from cracking. Urethane or epoxy would be my suggestion if you're wanting to give grouting another shot. But there's no guarantee your problem will be solved by only adding a support beam and a different grout.

03-14-2019, 07:18 AM
If I were to grab some 7/8" long screws and drove them in from underneath, this should add some strength by bonding the two layers of plywood together. This combined with the support beam might just do the trick.

03-14-2019, 07:41 AM
I think it's unlikely, Steph, that those 7/8" screws will bite deep enough into the top layer of 1/2 ply to hold. No reason you couldn't give it a shot though.

Since it appears you have access from below, and if this were mine, I would first add blocking under the visible, and currently unsupported, plywood joints. I would then install a beam to split the unsupported span of your joists. If you post how many joists need to be supported folks here can give you an idea of how to build that beam.

What I don't think you can fix, though, is the use of nails holding the layers of ply, and those are likely the source of the creeking (sorry, had to).

03-14-2019, 08:29 AM
And I'd recommend the Orvis Helios fly rod in 4 weight. Also very good for "creeking." How long can this go on? :D

But what Dan said, also.

03-14-2019, 08:37 AM
The subfloor is definitely nailed together, no doubt about that. I'll try and get some more pictures from the crawlspace to help out. In my living room area I had issues with noise and movement in the floor. I added a doubled up 2x6 (glued and nailed together) in the middle of the span, supported by a jack posts at each end. This helped a lot in this area and got rid of a lot of noise, springiness and the "sag" that the floor had.

03-15-2019, 09:53 AM
Here are some pictures of from the crawslpace. The kitchen area is roughly where the 1/3 strapping is tied to the underside of the joists. The joist are 2x8x12' on 16" c-c. The main support beam for the house is 4-2x8 laminated together and the outside wall is cinder block (behind the foam).

03-15-2019, 12:46 PM
By any chance were the nails used on flooring ring shanks? Also were the joints in the two layers offset?

One could, although not by the book, make a mid floor support girder with pier blocks planted firmly and a built up 2x8 beam and 4x4 or doubled 2x4 posts at ends and perhaps middle. This similarly placed to your strapping.

In the best of worlds, those piers would be poured below regional frost depth, but there's more than a good chance the crawl will be closer to interior house temp and humidity swings than exterior, so less subject to heaving.

03-15-2019, 02:50 PM
As far as I could see, I believe the second layer of plywood was installed with spiral/ardox nails, I can double check that. I don't know if the two layers were offset or not. Since they were not put down at the same I would like to think they are offset.

When I purchased the house the main support beam (4-2x8) was only supported by cold stacked cinder blocks on top sand. Not only were these "supports" too far apart for the size of the beam, over the years those blocks settled in the sand. The house was then raised and shimmed up back to level, but the house kept settling further. I decided to replace these supports with jackposts that were set on top of 2'x2'x4" reinforced blocks (referred to as cottage footings locally). I ended up adding two extra supports vs. what was there previously to reduce the unsupported span of the beam. Over the years I have "tuned" the jack post as the house settles level again.

The crawlspace is actually part of the building envelope and is as the same temperature as the rest of the house.

I've attached a sketch of what I was thinking for a support. I'd use either the above mentioned cottage footings or deck blocks as footins. The beam would then be supported by 6x6's with adjustable brackets as linked bellow. The other option would be jack posts again instead of the 6x6's but there's added cost to this.

03-15-2019, 03:28 PM
Interesting construction, how old is house?

I think your plan is good. Probably as good as could be expected given the unstable soil conditions it appears you have. Adjustable posts would be good, although the need to adjust periodically is a little concerning. It is what it is, I suppose.

I'd be inclined to put a known fixed surface somewhere so I could set a laser on it from time to time and do a little measuring. You can stick your tape against bottom of joist and see where laser line intersects. Kind of a running research project.

If "cottage blocks" are flat stepping stone things, don't bother. You want pier blocks, designed to support weight. Don't excavate a place for them and then backfill to desired height. Best to bear on undisturbed earth or as close as you can get.

03-16-2019, 08:47 AM
It's a 1970's built house, from what I've seen around here the builder had some questionable practices (using rough cut, unstamped lumber in many locations). I'm located in a valley which is largely sand. I've had to readjust the post in the middle of the house as the framing seemed to "settle". The main beam had some high and low spots in it from being under supported over the years. With the new post, some ended up in these low areas and it seems like the beam has straitened itself out a bit over time so I've compensated for that. I don't believe that the new foundations have moved much over time though.

I ended up with the cottage slabs as the deck blocks (similar to peer blocks) couldn't withstand the loading of the jackpost. I actually had a few of the jack posts punch through the bottom of the deck blocks. The cottage slabs have more surface area so they can distribute the load more evenly over the sand vs. the deck blocks too. According to the local supplier/manufacturer, these are meant for this purpose and they even have a slight indentation in the middle that seems meant to hold a jackpost.

When I set the new foundations in place for new jackposts I borrowed a laser and receiver from work. Not only was it useful in making sure all the different blocks were at the same elevation, I also looked at my joist to see where they sat in relation to each other. The long and short of it is that the joists seemed to follow the elevation of the main support beam (with the high and low spots).

For this new support under the kitchen I'll likely use the deck blocks. They are easier to get, easier to handle and there isn't that much weight here vs. the middle of the house.

Deck Blocks:

03-16-2019, 09:10 AM
I was thinking more like this, but what you link would work, I think. Flat top would facilitate wood post installation after beam is temporarily hung from joists. There wouldn't be any significant lateral load.

03-18-2019, 09:07 AM
Well I've picked up all my materials for the project, I should be tackling it during the week if not on the weekend.

04-18-2019, 01:39 PM
I thought I had posted an update to this, but I guess I didn't. I got the beam in and everything went well. The floor seems to have less bounce now than it did before, hopefully this extends the life of the floor.