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I want to install wood stair treads over a concrete and tile flight of stairs. The tile is porcelain tile.

I couldn't find any tutorial that addresses this specific scenario. Do I have to remove the top tile or have to drill holes to secure the treads (would rather not, but will if I have to)? Is construction adhesive sufficient? Tile is nice, flat and even.

May be obvious but I'm not in professional construction business. Just a DIY'er.

isherwood
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Armando Canez
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  • To be clear... You have a concrete/tile flight of stairs and want to stick wood over the top? Are you wooden treads at least nice wood? – Questor Nov 07 '23 at 17:44
  • Yes, they are nice oak treads. The reason for the change is mostly because of safety concerns because the edges of the treads are too sharp (sharp 90deg between riser and tread) and if someone slips there might be an accident where someone falls and hits this edge (aesthetics are another reason). – Armando Canez Nov 08 '23 at 19:45
  • FYI, I live in Mexico so construction codes are not enforced the same way as the US. – Armando Canez Nov 08 '23 at 19:47
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    Fair enough, but I can say from personal experience that such a difference _will_ trip people up who aren't expecting it. How much do you care about them? – isherwood Nov 08 '23 at 19:58
  • @ArmandoCanez construction codes exist (for the most part) due to safety concerns... Stair construction codes exist because of a large number of people--primarily English serving maids--kept tripping and dying because of poorly designed stairs. Each of your stairs need to rise/fall the same amount, the steps need to be a certain width, etc... Otherwise people will trip and fall, creating a worse safety hazard then the one you currently face. – Questor Nov 08 '23 at 20:20
  • Hi! My comment about construction codes was aimed mostly at the fact that there are many houses in Mexico that do not comply with some of these codes, since in some places they are not enforced, and probably my stairs are not up to code (speaking about the hard 90deg edge that I would suspect is not code compliant, since I see a probable accident). I realize that construction codes are important to follow, I was just saying I might not have a code compliant flight of stairs, not that I have a better chance of doing some hack that would not pass an inspection (which I do). Thanks for the input! – Armando Canez Nov 09 '23 at 23:20

2 Answers2

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IRC R311.7.5.1 specifies that the difference between the largest and smallest riser in a flight of stairs shall be 3/8" (9.5mm) or less. If your applicable code isn't based on that, it still very probably has very similar language regarding stair riser heights.

Unless you engage in an awkward (usually) overlay of the landings at top and bottom, which then end up having a transition to the rest of the floor (what makes them awkward) that's very difficult to manage with any overlay of non-trivial thickness.

As such, I expect you'll need to remove the tile to have any hope of making a wood overlay work, and it will be a fairly thin wood overlay at that. One of the faux-wood porcelain tile products might get close to the look you want with more likelihood of success.

Ecnerwal
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    I see your point. Are you talking about the first and last treads only? – Armando Canez Nov 08 '23 at 19:54
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    The rest of them should change by the same amount, so yes, it's normally the first and last where the problem shows up, unless the original staircase was non-compliant (I have lived in old, weird houses with old, weird staircases...they are *interesting* to use, at times.) The reason it's in code is that your feet get used to a certain step size (even if you've never climbed this particular stair before) and when a step is not that size, you may fall because of it, as your foot hits earlier or later than expected. – Ecnerwal Nov 08 '23 at 20:02
  • @Ecnerwal yeah, I have that problem with a poorly constructed porch. (That is on my todo list). It trips me up every single time I walk up/down it. Stairs that are excessively steep/narrow are not nearly as bad as stairs that are at different heights. Even if it is only the bottom/top stair step. – Questor Nov 08 '23 at 20:22
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Heavy duty construction adhesive will do the job, assuming that the tile is all well bonded. Use a 3/8" (8mm) bead in a zigzag or grid pattern and hit the perimeter well.

I'd be concerned about moisture, though. Wood over concrete is always a bit sketchy in that regard. You may see cupping as the bottom side expands from dampness propagating through the concrete, which will have enough force to tear the adhesive loose.

isherwood
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    I see moisture being an issue, but wouldn't the tile stop the dampness permeating through the concrete? (Again... not in construction, so my question may sound dumb) – Armando Canez Nov 08 '23 at 19:51
  • Grout lines and cracks would allow transmission and just simple retention due to the confined area would prevent moisture form equalizing – isherwood Nov 08 '23 at 19:57
  • @Isherwood I think it depends on the type of grout, waterproof grout exists. Though it is extremely unlikely that waterproof grout was used on tiles on stairs. – Questor Nov 08 '23 at 20:25