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Expert Answers
How to Prevent Saltillo Tiles from Developing Mold and Efflorescence?
QUESTION
How to Remove and Prevent Saltillo Tiles from Developing Mold and Efflorescence? - Our outdoor Saltillo pavers in our Southern California home's patio are about 24 years old. Over the years if green mold/growth has appeared on the grout and the edges of the tiles, a good scrubbing with a cloth and then a strong jet spray to rinse has cleaned them. Recently we have added more plantings that require more watering. The tiles are in more frequent contact with the water. Instead of green mold/growth, we have a black looking mold/stain that does not clean easily. Is this the deadly black mold? How can this be cleaned and treated to prevent it from coming back? Thank you.ANSWER
ANSWER - Mold or any type of microbial growth is a symptom of excessive moisture. Mold spores are ubiquitous. They are found everywhere. If there is high moisture or humidity at moderate temperatures mold will grow. It is more of a potential health hazard when found inside of a home where there is limited air exchange or circulation.It is clear that your Saltillo tiles are not installed properly or the conditions are such that they are being subjected to excessive moisture. Exterior tiles are to be installed in a manner where there is an adequate slope both on the tile surface as well as on the substrate membrane surface, and that the slope is directing water to a drain for adequate evacuation. Concrete slabs that are to have tile installed on them should have a vapor retarder under the slab that continues up the side of the concrete slab. This keeps water from migrating from under the concrete slab to the tile. There should be a separation between the adjacent soil and tile so water cannot migrate into the tile assembly. Sprinklers should not excessively overspray onto the tile; particularly if the tile surface isn't properly sloped to a drain. Otherwise you can get mold or algae growth and/or efflorescence precipitation causing an undesirable appearance.
You can clean the mold and efflorescence off the tile. You may need a deep cleaner to remove the black mold. You can see a list of cleaning and sealing product companies with links to their website on our website at www.CTaSC.com under Resources.
Once you clean the tile and it is dry you can apply a sealer that might mitigate the mold growth and efflorescence, but it won't prevent it entirely.
The only way to prevent the mold and efflorescence is to install the tile properly and add perimeter french drains to allow water to drain away from the tiles. Otherwise you have to plan on cleaning your tiles every so often to keep them looking good.
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How about mold and efflorescence on Saltillo inside? Our installer submerged sealed tiles in water before installing. We have efflorescence on several tiles and were really concerned about mold under the tile. Thanks!
The Mexican Saltillo tiles are so porous that some installers will soak them first so they don’t draw the moisture out of the thinset mortar adhesive or the traditional mortar that they may have used. The ANSI A118 thinset mortars have water retainers in them so it isn’t necessary to soak the tile first like what was done regularly 60 years ago.
Efflorescence is fairly typical with Saltillo tiles because they are so porous. The manufacturer does add lime to their Saltillo clay as a binder. Sometimes they will get Lime-Pops where little clumps of lime will expand and cause the tile to spall. The efflorescence can also be due to how the tile was installed and how much moisture it is subjected to. Getting some efflorescence is not unusual, but if it is excessive then it is because the tile is being subjected to excessive moisture.
It is unlikely to have mold under a tile if a mortar is being used over a concrete substrate. Mortar and Concrete have a high pH which mold can not thrive in. Plus to have mold, a type of microbial growth, you not only need moisture, a moderate temperature, but you need organic food. Mortar, Clay and Concrete are not a food source for mold.
It is possible to have microbial growth on the surface of the tile if the tile is outdoors and subjected to a lot of moisture and there are organic leaves and other material that acts as a food. Often this microbial growth is a moss.
A water supply line burst under our foundation and many of our indoor den’s Santillo tiles now have a yellowish residue around the edges or in the middle. What product and what method can we use to clean the affected tiles without damaging them. We really need your advice!! I read some where to avoid acidic cleaners.
Normally in a water loss event the insurance company would be responsible for paying to restore your tiles to their original condition, which might mean replacing them. Finding matching Saltillo tiles shouldn’t be hard as there is a lot of variation.
Saltillo tiles have always had kind of yellowish streaks or areas in them. So the water might have just activated the minerals in the tile that migrated to the tile surface as the water evaporates.
It could also be a stain from the adhesive that was used or if they used a slip sheet under the tile it might cause a stain. It is possible to evaluate the stain in a testing laboratory, but it likely isn’t practical financially.
There are poultices that can be used on natural stones and porous tiles like Saltillo tiles, but you need to determine if the stain is organic or petroleum or what. So it takes a trial and error process. There are companies who restore and seal tiles, so you might try to find someone who has that expertise and experience and pay them to try to restore the tile.
What is the best product to remove black mold on exterior Saltillo tiles?
If you have mold then it is because the tile is being subjected to excessive moisture. So cleaning the mold off doesn’t fix the underlying problem as the mold is the symptom of the problem.
Normally you can use a liquid detergent in water and use a scrub brush on an extended handle to wet the surface, let it sit for 10 minutes or so, and then scrub the tile. It is best to use a wet vacuum to pick up the dirty water. Then rinse the tile surface with clean water.
A white foam has formed on my Saltillo tiles on the floor next to a window.
Our house was flooded about a month ago and we had a French drain put in.
But this stuff is very white and looks like foam. Do you know what it is. Is there white mold? Thank you.
It is probably a form of efflorescence, which are minerals (forms of salt) that dissolve in the water and as the water migrates and evaporates at the surface of the porous Saltillos it precipitates the minerals. It is normally a calcium based material. One way to tell is put little a little cap worth of vinegar and add the white efflorescence. If it effervesce (bubbles up) is is a calcium material.
Assuming it is efflorescence you can buy an acidic cleaner to remove it.