I bought a 2400 sqf house. It now has carpet everywhere. Below the carpet I have concrete slab in the new part (built in 2009, ~800 sqft) and the old house has a wood subfloor with on top a solid hardwood flooring (old house, built in 1959, ~1600 sqft). As you see from the pictures, the solid wood (old house) is about 3-4 mm below the level of the concrete slab (new house). Sanding the old ugly (thin planks)solid wood is not an option.

If possible, I want the same flooring everywhere. I am considering 2 options: Engineered wood and wood-looking porcelain tiles. Ruled out Luxury Vinyl for aesthetic reasons.

I would like to have continuous flooring between the 2 areas without transition areas, for open floor effect (9 foot opening, see picture). However, I am afraid that differential settlings between the old and new house might crack the floor. I am willing to take the risk of no transition but I would like to estimate the cost of a repair caused by differential settling in the 2 cases.

Summarizing, the questions are: which of the two options tiles, and engineered hardwood, would better handle movement across a subfloor joint with no transition?

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  • Voting to close. You're asking many questions here, some of which are completely subjective and some of which are massively broad. Please ask one clear, specific, objective question per post. – isherwood Jan 25 at 21:37
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    To expand on @isherwood's comment: You have a lot of detail in the post, and great pictures, but this Q&A site works the best if you restrict yourself to one major question. In this case, I think it is "How do I deal with a 3-4mm difference in elevation between two rooms?" – IronEagle Jan 25 at 22:45
  • Ok I am gonna make it shorter and to the point – Millemila Jan 26 at 0:10
  • Hi, I changed the title to make it to the point. I removed the part on the kitchen, unnecessarily. I shortened the text and removed details. I added details to the picture. I made it a tiles versus engineered wood question, for house with different subfloors. Please let me know if you can reopen, I think it can be useful for many in the same situations. I think these are the essential questions that should be asked to make a good choice and estimate cost and labor, all questions are inter-related. – Millemila Jan 29 at 16:32
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    You still have 5 points listed under "My question" and each of those has multiple questions. That is the part that's far too broad. Pick one of those, possibly with a very closely related follow up, and focus this question on that one. Once you've got an answer to this, it may eliminate other questions, bring up new ones, etc. Feel free to ask new ones as you work your way through the design. – FreeMan Jan 29 at 16:55

I will answer one of your questions:

Put a transition in. Given the opening, I would put a single strip of tile that matches the frame depth, that contrasts with the tile on either side of it. So if you go with light coloured tile in both old and new part of the house, put a darker tile as the strip.

If you want to go with wood, do a single, or a few strips crossways along the joint. Run the others against that.

Put a tile line exactly on the junction of old and new. This way if part of the house shifts, the crack will be in the grout instead of breaking a row of tile. This may mean a double row of smaller tile.

Having a visible marker at the transition will reduce tripping if you can't level out the difference between the two sections of the house.

You probably should do a layer of Ditra or other isolation membrane for a project this big. I have twice not used it, but my largest project was an 8x12 laundry room.

Trying to make a floor that flows through multiple rooms has issues:

  • If one part of the house moves relative to the other the flooring is under severe stress. Having a natural movement joint relieves this stress,

  • Some years from now some accident (flood, fire, dishwasher leak, paint spill, uncaught dog pee...) makes it desireable to replace the floor in one room. Replacing a room in a much smaller disruption than replacing the entire level.

  • It would be more ideal to put a j-type transition strip in to hide the cracking during the seasonal changes. There are a lot of ways to handle this. – DMoore Jan 29 at 16:45
  • Thank you everyone. Seems I have options with a transition. But my first choice is continuous planks running across the joint, no transition, see updated figure. Is this feasible? – Millemila Jan 29 at 23:29
  • Also should i remove the old hardwood if I use Ditra? – Millemila Feb 2 at 13:39

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