OSB Mold issue in winter? Heated garage

[Ek9max]

So i'm moving into a new-to-me house in a couple weeks.

The garage has inslab heating and a drain. The garage walls were done in fire rated OSB (pre 2010 code) And the house side has drywall, tape, insultation, vapor barrier.

I'm getting the flooring done with a poly coating but my garage guy tells me that due to the winter months/heated garage that I will have a humid garage and the OSB will mould.

Any thoughts on this?

 

[NUTTSGT]

If that was true, 90% of the garages here would be covered in mold.

 

[bdbecker]

If you are concerned about it, you can get a humidity gauge for $10 and keep an eye on it this winter. If it seems like its out of hand, you can get a dehumidifier and run a hose to your floor drain.

 

[PassnThru]

If that was true, 90% of the garages here would be covered in mold.

I prefer to refer to it as 'patina'

It's painted - what would be the difference between the OSB and drywall with the same layer of paint. If it molds, it would be on the paint and would do it on either.

 

[Ek9max]

Also I can see like a 1mm gap between from of the sheets of OSB. Could moisture get in there and mould?

 

[Ek9max]

If you are concerned about it, you can get a humidity gauge for $10 and keep an eye on it this winter. If it seems like its out of hand, you can get a dehumidifier and run a hose to your floor drain.

Yea maybe I'll get a standalone humidity/thermometer. At what humidity would I start to worry?

 

[PassnThru]

Also I can see like a 1mm gap between from of the sheets of OSB. Could moisture get in there and mould?

They appear to be installed vertically so any gaps should fall over a stud.

 

[bdbecker]

Keep it below 60%

https://www.epa.gov/mold/mold-course-chapter-2

 

[TractorJeff]

You did state that it is a "New to me" Garage built on 2010 code. You don't say what City/State you are in so where is the mold in this 8 year old house now? 1mm gap is the result of OSB being installed properly so that the boards swell and contract without buckling.

 

[kbs2244]

Mold grows in still air.
Get a fan and run it 24/365.

 

[Ek9max]

They appear to be installed vertically so any gaps should fall over a stud.

Good point. I'm really not very knowledgeable with this sort of stuff.

 

[Ek9max]

You did state that it is a "New to me" Garage built on 2010 code. You don't say what City/State you are in so where is the mold in this 8 year old house now? 1mm gap is the result of OSB being installed properly so that the boards swell and contract without buckling.

I'm up in calgary, canada. Pretty dry climate. My reno guy just suggested taking down all the OSB to replace with drywall to avoid mould getting into the OSB. He said the snow would melt off the cars because of the in-floor heating and cause mould in the walls.

There does not seem to be any mold issues now. But I did notice the current owner duct taped his garage thermostat to "off". So maybe he never ran it ever. I plan to have it on all winter.

I was just looking for input that's all. I would have thought the floor drain would help enough to keep humidity down.

 

[GrayFlattop]

Echoing earlier comments, I would simply observe and gather data. During the winter, snow melts off my cars in the heated garage. I've never perceived anything that I would refer to as excessively humid. Walls and ceilings are covered with drywall - no mold observed there in 25+ years. Winter air feel dry simply because it cannot hold that much moisture. The floor drain should help keep the snow melt from pooling - assuming that the concrete is pitched properly.

The other factor to consider - every time you open or close the garage doors, there is a very substantial exchange of air volume.

I really don't think that you have to worry about this much at all. I could be wrong, but there are so many other things that would take priority on my worry list.

 

[Ek9max]

Echoing earlier comments, I would simply observe and gather data. During the winter, snow melts off my cars in the heated garage. I've never perceived anything that I would refer to as excessively humid. Walls and ceilings are covered with drywall - no mold observed there in 25+ years. Winter air feel dry simply because it cannot hold that much moisture. The floor drain should help keep the snow melt from pooling - assuming that the concrete is pitched properly.

The other factor to consider - every time you open or close the garage doors, there is a very substantial exchange of air volume.

I really don't think that you have to worry about this much at all. I could be wrong, but there are so many other things that would take priority on my worry list.

Now you have me curious.... . What would be on that list that I should worry about?

 

[BruceMc]

I'm up in calgary, canada. Pretty dry climate. My reno guy just suggested taking down all the OSB to replace with drywall to avoid mould getting into the OSB. He said the snow would melt off the cars because of the in-floor heating and cause mould in the walls.

If your guy is saying that drywall/sheetrock has some magic property that OSB lacks, I'd suggest doing a quick search on "drywall mold".

 

[kbs2244]

Mold problems and the OSB/drywall debate are two different things.
Either one does not cause or eliminate the problem.

 

[n20junkie]

If your growing mold on OSB, your going to grow MORE mold on drywall. Drywall absorbs a huge amount of water.

Regardless of the wall material, if your going to melt off cars, your going to have periods of really high humidity and that will lead to issues. Even if it was tile, it would likely grow mold.

 

[Ek9max]

If your growing mold on OSB, your going to grow MORE mold on drywall. Drywall absorbs a huge amount of water.

Regardless of the wall material, if your going to melt off cars, your going to have periods of really high humidity and that will lead to issues. Even if it was tile, it would likely grow mold.

So what do you suggest?

 

[Showkey]

So what do you suggest?

Don’t worry about it..............

All garages with wet cars have high humidity.......heated or not does not matter.........the cars might put 5 gallons of water on the floor per day. Your way ahead of 98% of all garages because you have a floor drain.

Push the water down the drain.
If it does become an issue ( unlikely) turn the in floor heat off.
Dehumidifier will not work in cooler temps, high cost of operation and garage is not sealed from air exchange.
Fan would help dry it out....slightly........but again a waste of energy. If there a mold issue the fan will guarantee they ( the mold spores) are well distributed around the whole building.
Forced air heat would dry the air out vs infloor heat.

There are prior threads on the topic where guys park outside all winter because they don’t like the water on the floor...........then there are the guys that worry the vehicle might rust more with warm temps of the heated garage. Again don’t worry about it.........it’s not going to be a problem.

 

[Blk88GT]

You're going to have a bunch of humidity when you bring in a snow covered car and it melts off. I'm not sure I'd tear down the OSB, specially if it's painted. But you will need to do something about the humidity for sure.

Keep the air moving and consider an exhaust fan. It's the only way I have found to vent the humidity out of my shop in similar conditions.

My previous shop was forced air/gas and I never had humidity issues like I do with the floor heat. Thankfully I no longer park in the shop every day so I can deal with it.

 

[GrayFlattop]

Now you have me curious.... . What would be on that list that I should worry about?

Ha! Things like - "Where will I find the space for another large tool cabinet?" "Does buying more ratchets mean I have a problem when I already have over 60?" "When I die, will anyone appreciate my tools?" - although I don't spend a lot of time on that one. "do I really want to spend the money moving just to have a larger garage / shop?"

You know - important stuff.

 

[Ek9max]

You're going to have a bunch of humidity when you bring in a snow covered car and it melts off. I'm not sure I'd tear down the OSB, specially if it's painted. But you will need to do something about the humidity for sure.

Keep the air moving and consider an exhaust fan. It's the only way I have found to vent the humidity out of my shop in similar conditions.

My previous shop was forced air/gas and I never had humidity issues like I do with the floor heat. Thankfully I no longer park in the shop every day so I can deal with it.

Did your shop have a drain?