I just picked up my porcelain floor tiles from the warehouse. They were stored outside in the rain for a week. They're still wet and being aired out now. But they smell of mold. Is this bad news?

  • If there is mold on it, give the tiles a bath in a tub of water with a bit of bleach in it. – DA01 Apr 24 '13 at 17:57

If they are true porcelain, they have not absorbed water. Porcelain are rated for exterior applications.

Some people generically call ceramic tiles porcelain, which may not be rated for continuous water exposure.

The porcelains will completely clean up and not harbor anything other than a surface covering of mold, which might have come from the packaging.


Tile Council of North America (TCNA) Porcelain Certification

Porcelain tile is defined as an impervious tile with a water absorption of 0.5% or less as measured by the ASTM C373 test method. There are, however, many instances in which tile not meeting this standard is advertised and sold as porcelain tile. Marketplace confusion, installation problems and even liability concerns can result when non-porcelain tile is misrepresented in the marketplace.

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  • I agree. I just wouldn't keep dirty tile. Also I have bought porcelain with a lot of grooves in the back. Wouldn't be happy about scraping mold out of them. – DMoore Apr 24 '13 at 15:49
  • thanks - this is the position which was taken by the staff when I picked it up. they said it is 100% true porcelain. – skybreaker Apr 25 '13 at 3:09

I would return them if they were given that way to you. First I would not power wash them. I know my power washer would go right through the porcelain I just installed or at the very least mark it.

Also if there is mold growing and you don't get it all off or if you don't get all of the dirt off you are taking away from the bonding area. The mold too can continue to grow after being installed. Unless you got an incredible deal on the tile I would return it.

If you have to keep it... I would mainly worry about the back of the tile and the sides. I would hit it with a bleach mixture to stop mold growth. A scouring sponge should do. If it is really that bad I might bust out an SOS pad or two. Also make sure the tiles are dry before installing.

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  • I was worried about that. It seems odd to me that all of the major tile warehouses seem to store some of their tiles outside. Is this normal? I asked the guy if it mattered that the tiles were wet and he said "no - the tile adhesive is wet when you install them so what's the difference?". How long would I have to leave each tile out individually to make sure that they're "bone dry"? Thanks – skybreaker Apr 24 '13 at 15:28
  • I mean most tile is in boxes. Boxes + moisture is not good. Not sure where you shop but I never get wet tiles. Maybe this is a regional issue. – DMoore Apr 24 '13 at 15:30
  • Just getting them wet is not a problem, after all they will get really wet if you cut them with a wet saw. Mold is more of the concern here. – auujay Apr 24 '13 at 16:21
  • The wet comment was more about the bond to thinset or whatever he is using. Don't want that mixing with bleach/cleaning agents. – DMoore Apr 25 '13 at 5:10
  • I would take issue with "bone dry". Only one situation would call for dry tile.. using mastic for installing. Mastic should only be used in DRY locations AND on vertical (non walkable, non-weight bearing) surfaces. Dampening BOTH tile and substrate (especially with cementitious backer board) is called for when using cement based thin set mortars. – HerrBag Apr 25 '13 at 10:07

Power washer + mild soap = smell problem solved.

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