Epoxy floor snag - unexpected moisture spots

[Trrexhouse]

I have been getting ready to start a floor prep. Removing all my junk and finding a place for everything else has been a challenge. I did the low cost moisture test with plastic taped to the floor for 48 hours ; dry as a bone. This past week we had a full day of rain. When I got home that evening I noticed wet spots on the floor. Not wet to the touch but what I can only describe as moisture spots. The next day they were gone. I never noticed this before but to be honest I never looked till now. There were no cars in the garage so the water didnt come from outside. Nor did it trickle in . I live 2 blocks away from a canal so my water table is low.

I want to know if I should address this before doing my epoxy job. Or maybe I should do the job on a dry day and forget it . Will this moisture thing affect the floor once it has cured? Any suggestions? Thanks

 

[thegarageguy]

More than likely you have a high rate of gas vapor emitting through your slab. A calcium chloride test will determine the existing amount. Anything above 3% per 1000 sqft per 24 hrs is not recommended by any or most manufacturers.

The solution is a negative side vapor barrier, then your preferred epoxy poly system

 

[tncatadjuster]

Was there enough of a sudden temp change to cause it to sweat on top?

 

[LegacyIndustrial]

I have been getting ready to start a floor prep. Removing all my junk and finding a place for everything else has been a challenge. I did the low cost moisture test with plastic taped to the floor for 48 hours ; dry as a bone. This past week we had a full day of rain. When I got home that evening I noticed wet spots on the floor. Not wet to the touch but what I can only describe as moisture spots. The next day they were gone. I never noticed this before but to be honest I never looked till now. There were no cars in the garage so the water didnt come from outside. Nor did it trickle in . I live 2 blocks away from a canal so my water table is low.

I want to know if I should address this before doing my epoxy job. Or maybe I should do the job on a dry day and forget it . Will this moisture thing affect the floor once it has cured? Any suggestions? Thanks

As GarageGuy mentioned you can do the more accurate test, you may still want to stick with a water-BORNE epoxy system, less likely to have issue with a little water vapor. If you live that close to a water source you should have a high-water table. High-water table meaning you have ground water close to the slab, low water-table meaning far from the slab. Unless you meant something else??

 

[Trrexhouse]

Yes, sorry I mis typed . I meant high water table. I am going to do the calcium chloride test. That picture looks horrible. Think I'll have a stroke if my floor looks like that after all that work ! Thanks Tim

 

[thegarageguy]

That picture looks horrible. Think I'll have a stroke if my floor looks like that after all that work !

I've had much worse....imagine 2000 sqft of continuous bumps and blisters like that....so bad I was embarrassed to take pics...it's a nightmare

 

[bigjon]

Is the brown liquid coming from the blisters?

 

[thegarageguy]

yes...contaminated slab as well

 

[Trrexhouse]

I ordered a 3-pak of cacl test . Should I test as soon as I get them or during another day when rain is expected? The moisture spots were only visible when it rained so I figured testing during rain would make sense. Thanks, Tim