Musty basement? damp garage walls?

[fryjack2]

We have one part of our basement that smells musty despite running a dehumidifier.  Our basement is odd as it is 3 different levels all 2-ish steps above/below each other in a somewhat  U shape.  Our garage faces the gym ( with tile flooring)  if the garage door is behind you, and the mudroom (that smells musty and has LVP flooring) shares a wall with the garage ( the right hand wall of the garage when the garage door is behind you).  The curve of the U is not connected to the garage but connects the mud room and gym.

We had a company come out last year when we noticed a wall in the mudroom was warping a bit.  They noted moisture, but no water.  It poured rain a few days while the drywall was off and we saw no water coming into the house. Thats when we started running the dehumidifiers ( oops. We should have been doing that all along) and the company waterproofed the wall and rebuilt it.  Another company came out and told us we should put in sump pumps and dig drains and take down all the walls and redo them with waterproofing.  We didn't do that because it seems excessive as we didnt have standing water or any water when it has rained in the 2 years we have owned this home.  

The bottom 6 inches of the garage walls on the mudroom and gym side feel or appear damp sometimes.  They are made out of some sort of drywall type material that crumbles.  There was a small spot of mildew&start of mold in a corner when we had a stretch of really humid days in July.  We cleaned it with bleach and it has not come back.  A moisture reader shows normal- levels of 35ish in random spots.  

We are working with a guy who thinks the moisture is humidity coming up from the garage floor.  I can see that being the case based on google. LOL.  

We do live in a home with a sloped backyard that slopes towards the house. The previous owners of 15 years said they did not have water issues. We had a water specialist assess the house before we moved in and he said the house was fine. 

I think we need to at the very least take down the garage walls and redo them in a way that prevents the moisture from creeping up into the walls.  But do we need to spend 40k on installing sump pumps, outdoor drainage, and taking down all the basement walls? 

Any thoughts? 

[orval]

Have you checked the actual concrete of the floor? Moisture may not be really visible but creeping in. See this article. It could be enough to damage the bottom drywall that touches the floor I would think.

www.buildings.com/news/industry-news/articleid/21943/title/signs-concrete-floor-moisture

[fryjack2]

orval- our garage floor seems to be dry, but I think I’ll do the plastic I’m on the ground test. We did get a quote to epoxy it which I think we will do no matter what as the concrete is cracking in places and is super old.

[k3am]

Our prior owners also told us that they'd never had any water issues. The inspection showed that there had been issues AT SOME POINT in the last 60 years, but everything was dry. Needless to say, we had a very, very, very wet year, and we now have sump pumps and french drains, and still have issues with humidity under the house.

It was a repair that we may or may not have needed to actually do. The pumps have never gone off since we've had them. I figure.. it's our crawlspace. The part of our house that the entire rest of the house is built upon. Not a fun investment, but I think it was a necessary one.

[fryjack2]

k3am. What happened during the wet year that made you get the sump pump and drains?

Our basement is not a crawl space, it’s 4 rooms that we use (lvp flooring or tiles and drywall or cement walls) so I want to get the issues resolved, I just want to make sure we have an actual cause of the issue before dropping $$$$.