Wet Floor

[iamoasis]

Hello,

I live in Canada and house was built in 80s. The climate this winter has been very mild and my 2 car garage is constantly very high humidity. This is typically seen every spring but due to mild winter, it's been months like this. The garage walls are insulated (spray foam), ceiling blow-in and the garage door is insulated. I purchased a dehumidifier (Alorair HD55) which works well at pulling moisture but the garage floor remains wet and humidity high. I'm not the original home owner so I can't say if a vapor barrier was installed underneath the slab but my guess is no. I can say with certainty that thye used pre-cast hollowcore slabs for the flooring. I'm sweeping the garage floor daily and puddles are being pushed out, only to show up again not long afterwards. I'm trying to limit the amount of snow we bring in. I kick and remove as much snow off the cars before parking inside. I have a large 36in industrial fan to move air and a 5kW heater.

Would there be any added benefit to seal the concrete floor to limit the moisture wicking through?

I appreciate any help.

 

[geneg]

Hello,

I live in Canada and house was built in 80s. The climate this winter has been very mild and my 2 car garage is constantly very high humidity. This is typically seen every spring but due to mild winter, it's been months like this. The garage walls are insulated (spray foam), ceiling blow-in and the garage door is insulated. I purchased a dehumidifier (Alorair HD55) which works well at pulling moisture but the garage floor remains wet and humidity high. I'm not the original home owner so I can't say if a vapor barrier was installed underneath the slab but my guess is no. I can say with certainty that thye used pre-cast hollowcore slabs for the flooring. I'm sweeping the garage floor daily and puddles are being pushed out, only to show up again not long afterwards. I'm trying to limit the amount of snow we bring in. I kick and remove as much snow off the cars before parking inside. I have a large 36in industrial fan to move air and a 5kW heater.

Would there be any added benefit to seal the concrete floor to limit the moisture wicking through?

I appreciate any help.

Only if you seal the bottom of the slab! Sealing the top will have limited success. I'd almost bet that there wasn't a vapor barrier installed. I've had a similar issue in my shop & have found that ceiling fans blowing down & a wide squeegy are about the only methods that help. Also helps to heat consistantly, not occasionally. Dehumidifiers typically also work better at higher temps.

 

[RegeSullivan]

I'd suspect you have additional issues with water under the floor. Any signs from outside that you have a drainage problem?

 

[ConCretin]

The moisture on your floor probably isn't water coming through the concrete. If they used hollow core plank that aren't in contact with the soil below, it's almost certainly not. It's more likely condensation from warm, moist air in the garage coming in contact with your cool concrete floor. Dehumidify the air to eliminate the condensation.

 

[iamoasis]

I'd suspect you have additional issues with water under the floor. Any signs from outside that you have a drainage problem?

No drainage issues. Concrete around exterior is sloped. There is snow accumulated on this said concrete at times.

 

[iamoasis]

The moisture on your floor probably isn't water coming through the concrete. If they used hollow core plank that aren't in contact with the soil below, it's almost certainly not. It's more likely condensation from warm, moist air in the garage coming in contact with your cool concrete floor. Dehumidify the air to eliminate the condensation.

So I guess the only solution would be a heated floor?

 

[ConCretin]

So I guess the only solution would be a heated floor?

That would be really nice if you could figure out how to do it. I'd limit moisture as best you can and a try a dehumidifier.

Just curious. You mentioned hollow core plank. Is there a crawls space or void underneath?

 

[geneg]

I didn't notice the hollow plank, assumed a slab on grade. Years ago did a parts mezzanine at a Honda dealership with hollow core. The hvac contractor used the cores as transfer ducts. Inlet going into the end of the core at one side & a register cut int the top at the other end. I don't remember any complaints. He didn't do every core, just a few across the area. Just pipe warm air thru your slab.

 

[Shea]

Running a fan across the floor can help. The swirling air does not have time to sit on the concrete surface to condense.

 

[iamoasis]

That would be really nice if you could figure out how to do it. I'd limit moisture as best you can and a try a dehumidifier.

Just curious. You mentioned hollow core plank. Is there a crawls space or void underneath?

Nothing underneath. The garage is attached but no living space under.

 

[RegeSullivan]

An industrial fan, 5kw heater and a dehumidifier seem like it would handle the humidity in an insulated 2 car garage well enough to keep puddles off the floor in most weather. I'd be looking for outside air leaking in. I could understand a little occasional dampness because the floor is colder than surrounding air but with all the mitigation in place puddeling seem excessive.

Short of a number of small air leaks adding up to a major intrusion or water being introduced to the spaced I'm stumped.

 

[iamoasis]

An industrial fan, 5kw heater and a dehumidifier seem like it would handle the humidity in an insulated 2 car garage well enough to keep puddles off the floor in most weather. I'd be looking for outside air leaking in. I could understand a little occasional dampness because the floor is colder than surrounding air but with all the mitigation in place puddeling seem excessive.

Short of a number of small air leaks adding up to a major intrusion or water being introduced to the spaced I'm stumped.

I appreciate the help. I will continue to heat the garage consistently rather than occasionally. The higher temp will allow the dehumidifier to operate more efficiently. In the spring/summer, I will look to seal all gaps where air could be leaking.

 

[Crowbarman55]

I have had the same issue in Michigan for many years. I know that no vapor barrier was installed under the slab. Two years ago I installed a Mrcool Mini split and Race Deck solid tiles. Solved the moisture problem for me.
Todd