Q&A / 

Efflorescence Brick Floor

Caitlin Jenkins and her husband now live in Basel, Switzerland. But the building has a brick floor and she's dealing with efflorescence. Let Caitlin give you the details:

"Hi Tim,

I saw your YouTube video on efflorescence  and I'm wondering if you have any particular recommendations for our situation.

My husband and I just moved into a very old building in Switzerland. We have clay floors in the basement room, which we are trying to make our bedroom.

There is definitely efflorescence on the floors. Look at my photo, but it's not nearly as bad as it looks (just a little bit of crystals after about a week).

The room is humid - but all of Basel, is damp this time of year, and we haven't otherwise noticed any issues. We run a dehumidifier occasionally just to be safe (protect our clothes).

Mostly, cleaning up the chalk is irritating. So, a few questions...
1- do you have any ideas for how to decrease the chalk buildup? Oil, sealant?
2- is there any risk of putting patio tiles over the floor and just not worrying about it most of the time)?
3- is there anything we can do differently to maintain the space?

NOTE: there isn't a leak anywhere and we don't own the apartment. We're close with the landlords so we can make recommendations, but digging up and relaying the brick (for example) would not be an option (also because the property is historic and protected).

Thanks much!"

You can see the unpleasant salt deposits that we know as efflorescence. Photo credit: Caitlin

You can see the unpleasant salt deposits that we know as efflorescence. Photo credit: Caitlin Jenkins

Here's my reply:

Caitlin, I can understand why you're running the dehumidifier to stop mold from growing on your clothes. That's a great idea.

However, that's exasperating the efflorescence issue. The more water you pull from the air, the more water is drawn through the brick.

When that happens, the salts in the water are left behind.

The salt is harmless and it's just an appearance issue.

The only way to stop it is to exhaust the supply of salt in the ground or brick - and that could take centuries - or to stop the water from coming up through the floor.

It's virtually impossible to stop the water as that should have been done during construction. The issue is, hundreds of years ago the Swiss builder didn't have access to high-performance cross-laminated vapor barriers to put on the soil under the brick! Go figure!

Covering the floor with another material will not solve the problem.

Applying a sealer MAY stop it, but it's an issue of finding a clear film former that will not peel from the vapor pressure.

It's a real conundrum. Are you able to vacuum it up fairly easily when you see it, or are the salts pretty much embedded in the brick?


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