Does this look like mold issues, what can be done?

[sprdave]

Our (parents) house is over 100 years, part with dirt floor, stone foundation and the like. It has a strong damp/musty smell. They are trying to run (portable) dehumidifiers but it's still close to 70%

Does it look like (could be) mold issues in these pictures?

https://www.flickr.com/photos/126695439@N04/

And what can be done practically (haven't been able to convince a new house ). Talking about spray foaming the foundation walls..would that be effective or worse?

[kurt]

Of course it's mold. It's an old damp musty smelling basement.

Whether or not it's a problem is open to various interpretations.

[Marc]

Does the area with a dirt floor ventilate outdoors?

Marc

[Scottpat]

Typical problems with a 100+ year old home with a stone foundation and a basement. Keep in mind that any waterproofing not done from the outside is akin to putting a bandaid on a bad case of roadrash! You can cover some of it but eventually it's going to seep on through. It is virtually impossible to make a stone foundation watertight, most folks just try to manage seepage.

[kurt]

Yes. Even if you foam the interior, you need to provide a drainage plane membrane between the foam and the foundation, and the drainage mat would need to discharge/drain into a drain tile and sump.

After that, you'd want to also install a vapor retarder for the floor, which means a new concrete floor system. Put it all together, and it seems like it might be more than you want to bite off at this stage. Or not. Depends on where you're trying to go.

[Mike Lamb]

Accept the fact that the basement will be damp and the foundation will likely have seepage. Waterproofing would require exterior excavation and you don't want to go there. $$$$$. Make no plans to finish the walls. I'd want any dirt floor areas paved.

I doubt humidifiers can handle all the damp rise. I might try a ventilation fan run by a humidistat.

Exterior grading and roof water management is critical.