100 year old subfloor issues-pls help!

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peanutbelly

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Hi everyone, first time poster here. I've run into some questions as I'm in the process of collecting bids on installing 16x24 porcelain tile in my 135 square foot kitchen. Here is the background info-

100 year old house. Floor joists under the kitchen are 2x8 and spaced 16" apart except for the one closest to the wall which is more like 20-22".

5 years ago my husband and I tore out the linoleum flooring in the kitchen and replaced it with 12x12 ceramic tile. We did this project ourselves. We screwed 1/4" hardibacker down first and tiled over it. We had tiled a small bathroom before so this wasn't our first experience with tile but certainly our biggest.

Fast forward 2 years and we started getting some cracks and loose tile in the SW part of the kitchen. Our grout was also starting to come loose in several places but I attribute that to some mistakes we made in installing the grout and the fact that we used a grout that didn't allow for any flex whatsoever.

We've embarked on a total kitchen remodel at this point-new cabinets, tile, countertops, drywall, etc. We took the kitchen down to the studs and are in the process of building it back up. Drywall is in, we're down to subfloor (again).

I've explained the issues we previously had with tile to several tile guys who've been out to give us bids. We really like 2 of these guys and the prices are the same but they've given us 2 totally different solutions to the issues we've raised and I honestly don't know what to make of them-

Guy 1- his solution is to screw a 4x4 into the floor joists from below as close to center as we can and add 2 jack up beams to support the 4x4 to minimize movement in the subfloor. The kitchen is above our garage so this would be easy. He states that the issue is most likely attributed to the fact that our joists are 2x8's and not 2x10's or 2x12's used today. He recommends 1/2" hardibacker screwed down as a substrate for the tile rather than the 1/4" we used previously.

Guy 2- his solution is to use 1/2" cement board and he thinks this alone will solve the issue. His installation method is to screw down the corners and use galvanized roofing nails to nail down the rest. He would also use thinset to glue the cement board directly to the subfloor as well as to set the tile.

Both guys will use a white thinset that allows for some flexing and we've already made the decision to grout with Epoxy for other reasons (90% housetrained dog spends the other 10% of his life in my kitchen).

I'm at a loss as to what method is better.... Sorry for the long post, I would just be devastated if we started encountering loose/cracked tile again after all of this....

Any thoughts? We need to make a decision by Tuesday.....
 
Welcome to House Repair Talk. What is the material and thickness of the existing sub-floor? What are the spans of the floor joists?
 
I would install the 2x8 joist that is missing and sister on 2x10s or 2x12 to each of them with glue and screws. The bigger joist do not have to be notched over the walls in the garage. I single 4x4 will add nothing and the other guy is out to lunch. The problem is they just know tiling. 2x10s would be plenty for about a 12ft span
 
1/2 cement board will add 0 strengh and will do nothing to stop the floor from flexing. Tile board is to give the thin set something to bond to and nothing more.
Hard to tell you what to do exactly without being there to see it, but one thing we have done is use triple 11 1/2" LVL's through bolted together as a center beam running down the middle of the span with tripple 2 X 6's on the ends as jacks and one center lolly coloum in the middle. Before the lolly went in we had to cut out the floor 24" X 24" X 24" deep and fill it with concrete to act as a footer. The floor will be sagging by now so the center will need to be jacked up to get it level then screw the lolly up to hold it in place.
The lolly will need a 1/2 steel plate 5 1/4 X 5 1/4 sq. with 3/8 holes predrilled into the corners for lags to hold it in place at the top, and to spread the load.
Adding wider floor joist is something most people do but there's flaws with that idea. The wider joist will need to be all one piece, on the ends your going to have to cut them to be able to fit them in place. Once you cut them your back to the org. width and there prone to cracking right where the two cuts meet.
 
Joe; You do not have to notch the wider joists, all you want to do is take the flex out of the 2x8s
 
Neal unless the new floor joist run from one side of the foundation to the other so there fully supported there not going to take much of the spring out of the floor and also will do nothing to take out the sag in the middle.
A 100 year old house most likly was ballon constrution so every floor joist will have been cut on the ends so it would rest on the foundation.
 
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Thanks for the responses-

I don't think we're prepared, or skilled, enough to take on what Joe is suggesting. I took some pics in case this helps. As you can see, another area of concern is the amount of holes drilled into the 2x8's as I'm sure that weakens them as well.

All we want/need to do is remove the flex from the floor. If there is an easy way to do that by adding support to the joists somehow that would be my preference...

Thanks again,

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Thanks for the responses-

I don't think we're prepared, or skilled, enough to take on what Joe is suggesting. I took some pics in case this helps. As you can see, another area of concern is the amount of holes drilled into the 2x8's as I'm sure that weakens them as well.

All we want/need to do is remove the flex from the floor. If there is an easy way to do that by adding support to the joists somehow that would be my preference...

Thanks again,

So, I've been back downstairs thinking about this....

I can't really sister the joists as there are too many wires, plumbing, etc running through them...

What if I did some bridging with 2x8's every foot or so between the joists? In addition, we are installing an 8 foot 4x4 support beam with 2 posts. Does anyone think this would be sufficient? I should add that when we tiled the first time and ran into issues they were fairly isolated-it wasn't the whole floor that was affected in terms of loose/cracked tile. There isn't a noticeable sag in the center of the kitchen-1 really big squeeky area but that is about it. I had my husband jump on the floor in several places while I was in the garage. No noticeable movement from what I could see. Of course, he is only 170lbs too.....

I really appreciate the responses so far, just trying to sort out a reasonable solution. We ended up hiring tile guy 1. He starts Thursday. Uggh, this is stressful. Thanks in advance for any input.
 
You would need a plumber and electricion in order to do any sistering so I think your back with Joe suggestions and a 4x4 will sag so you would need some sort of beam and it wants to be supported down to the foundation. You do not want to put the weight on the floor. How long of span are we talking about. How long are joists and how long is it the other way and can the beam span to over the foundation.
 
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