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Floor Tile Project Old Mudroom/Porch

3 months ago

Because I know a lot of tile masters are on this thread, I am posting this here. I have done 2 bathrooms with a great outcome with the help of tilers on this forum some years back. So, as my son asked me several days ago, "Mom, is this the last frontier?" I laughed and said yes. He had helped a lot with the heavy work 12 years ago when I did my first bathroom gut job and rebuild from the subfloor up. He's done with college and career moves and travel and is back in the area. I'm hoping he and my DH can be some needed labor. I just turned 71, retired 6 months ago, and feel I have one more tile job in me. I'm going to go with small format tile that is no larger than 12x12, but would prefer something like 8x8. This is an old house and I feel its in keeping with the structure.

How should I consider taking this down to a level that will get me the lest amount of added height to the new floor elevation?

So here is the breakdown:


I want to tile the floor with porcelain tile. The floor is too high at this time and a layer, or 4, need to come out. I took samples of the floor material to my local testing company to check for asbestos, and it came back positive for the top vinyl layer's backing. So asbestos abatement is in order.

The layers to this floor, from the top down, are:

  1. top layer old glued down vinyl from the 60's?
  2. Plywood 1/4" underlayment for the vinyl
  3. Blackish layer is composed of cellulose and hair
  4. 3/4" fir T&G from back in the day
  5. 3/4 diagonal sub-flooring.

I might be up for a total gut of the flooring to the joists. I thought I could remove these layers, either down to the T&G, which is what I did on the neighboring room in 2012, or to the diagonally placed sub-floor.

Deflection is marginal for ceramic tile, with the 21"o.c. 2x8 fir joist from the 100 year old house. The joist are 2x8 by about 9.5 or 10 feet long. The room is about 100sf in size. When I use the JB forum deflector calculator I get OK for ceramic with 20"oc and result of "This translates to a deflection of L / 384." With 10' long 2x8 joists. If I put in 22"oc it fails to meet the critera for ceramic with results as a thumbs down and "This translates to a deflection of L / 349.".

This room is over an inaccessible crawl space, so I cant go and work the joist from below, to add extra joists. That is what I did in 2012 where we added joists between the existing joists to a new 10" on center 2x8 by about 9.5 or 10 feet long for my stone floor. BTW that stone floor has held up marvelously!

I am constrained that I can't raise the header to the entrance door to accommodate elevated floor. I have about 1/2" wiggle room for height of floor increase.

This is the profile, with the vinyl on top, then the 1/4 ply, then the cellulose layer, then 3/4 T&G, then recessed is the diagonal 3/4 subfloor:

The rise is wood, it looks like sitting on top of the concrete stairway to the basement:

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