The type of mold cannot be determined by a visual examination.
Most mold is not much of a problem to eradicate and does not bother many people to any great degree. Others are more sensitive.
There are remediation companies, or you can learn easily enough how to do the job yourself.
All the drywall & insulation must be removed, the area cleaned, and a liberal application of diluted Clorox applied. There are fancier chemicals to kill mold and spores, but Clorox does just fine. It is a little smelly and wet during the work, but you try and use as little water as possible to perform the job.

I would be more worried about what else is wrong.

I think all old houses have some mold, but not all have problems with it. It sounds like you do, though.

You didn't mention where you are; that may make a difference in how big a problem you have.

I am a bit confused about your 1914 house with a modern foundation. How did that happen? And why?

On the good side, you live in an older house which is most likely no where near as air and vapor-tight as modern construction, so it will dry out much more readily.

Now you may have an awful problem, or merely a big PITA that can be handled with just some extra work and costs. It's hard to tell from your description. But if it's the latter, here's what I'd do.

Immediately start using dehus in any space that is damp. If it's totally impractical to dehu an area, get fans on it to move air through and out to the outdoors, not just around inside the house- always presuming that you are in an area where outdoor air is less humid than inside the space.

Invest in some small temp/hygrometers (they run $20-40 each online). I have about a dozen perched here and there and they help me monitor conditions.

What kind of cellar flooring or ground cover do you have? Even if you have concrete, unless its a modern pour, it's likely it has no vapor barrier/retarder underneath it. That will have to corrected to dry the building out.

Are all sumps in perfect working order?

Have you thoroughly examined the structure and located all sources of additional water penetration: window/siding intersections, roof, guttering, exposed foundation at grade, etc? You need to find where the water or moisture is getting in and block it.

Now about the sheet rock with mold behind it. Well, you're going to have to remove it, and probably the adjacent insulation and vapor barrier and stuff behind it. I would also paint any wood in the wall with anti-mold chemicals (either specifc antifungal stuff your can get at janitorial supply houses or just scrub well with a very strong mix of water and Clorox). Then let the cavities get throroughly dried out before you repair the wall and enclose it again.

So, here's a possible order of march:

Get yourself some mid-grade breathing protector. (Better than just paper masks, but not total rebreathers, either; your challenge here are spores, dust and anti-mold chemicals, like strong solution of Clorox). You'll need lots of plastic or latex gloves and probably a couple of changes of coveralls and a pair of rubber boots if you're really going to be wading in it.

Buy Clorox, and cleaning supplies, including lots paper towels and big sturdy trash bags.

Buy dehus.

Buy hygrometers. (You might think about a wood moisture meter as well, though I have never used them. These help you assess how wet the wood is, so you know when it's dry enough to begin reclosing cavities.)

Buy fans.

Spray or wipe down any mold you can see with a strongish solution of water and clorox and then remove the wall itself if you feel it has penetrated the sheet rock (and likely it has.) Keep going until you're past (in both depth and width) of any visible contamination.

After removing all the moldy stuff from your structure get the dehus and fans cranking. Monitor humidity throughout the day and night, so you can get a feel for when to runs fans and dehus.

While the affected areas are drying put your time into finding sources of water or moisture and solve those problems.

Roof is a biggie, but you sometimes can put short term patches on if you've lots of things that need attention. Can't work on it during the winter, though.

Look at every penetration and see if you need caulking.

Examine your rain handling system. Are your gutters and down spouts OK? What happens to the water when it hits the ground, where does it go? You may need some french drains or tiling to get it away from your foundation. You may need to do some bush or tree trimming, after you sort things out. Unless it's something clearly causing a probem, I always wait since you might be sorry if you rush out with the chain saw. (I always am if I don't think carefully, first.)

Then think about how you can block rising water vapor from under your house. This will make a big difference in your indoor environment, and reduce the need for constant dehuing. Soil vapor barrier installation is one of those things that can be done through the fall season (unlike roofs) so I'm putting it later on in the list of things to do though it is quite important.

OK, I hope I haven't depressed you too much, though you sound quite worried already. You've probably heard about those infamous mold-palaces that wind up in endless litigation or are finally burnt down because of mold problems that can't be cured. Try to cheer yourself up with this thought: I think almost all of those are new houses sealed up to modern standards. Houses of your age are generally no where near as tight, nor are they made of the same materials so I think you're already ahead of the game. (Unless, and this is a big if, your house is in New Orleans and was flooded in Katrina... then my measures detailed above are too puny, and probably too late. But you would have mentioned that, right?)

Are you a new homeowner? Did you have a house inspection and were any of these issues mentioned in the report?

Don't abandon the dream of owning an older house. Remember that it has stood up to many challenges and will likely be here long after many modern structures have degraded.

A general rule for all molds and fungal infestations is that they need a couple of things to flourish: proper temps (though this differs among the various species of molds); still air; high relative humidity or moisture condensation; darkness and their preferred range of foods. Unfortunately sheet-rock paper is one of their favorite foods, so is really saturated wood for some species of molds. Other molds thrive on ordinary dirt, soot and grease that can accumulate inside older buildings;those species can be quelled by removing the dirt.

However almost ALL molds can be inhibited or arrested by removing one or more of their needed requirements of life: (moisture, food, still air, lack of light or correct temp range). In many cases you can manipulate the environment enough to stop it in it's tracks. Then you have a shot at reducing or removing (physically, mostly) the spores and growths. You can kill most of the spores and growths, but probably never expect to completely sterilize the area. Since these are house-infesting molds which, while unhealthy to be around at high concentrations, do not grow on us. Therefore reducing the total fungal-load in the building environment, and then keeping it under control is enough to make things OK again.

In other words your task is to get rid of the excess overgrowth and change the environment enough to discourage another build-up. That's what makes it a do-able propostion. Complete removal would be nearly impossible and it would recontaminated as soon as the first breeze blew by, anyway.

If the mold is confined to only one or more rooms, I would try to seal them up to separate them from the rest of house, particularly if you are living there. You do need ventilation in the mold rooms, but keep adjacent windows to unmoldy rooms sealed up if you're running exhaust fans outward during demo work. You could also tape shut doors between the "clean-er" rooms and the moldy areas when you're cleaning up - and no doubt letting a whole lot of spores take wing. I would also shower and wash my hair every day during the worst of it. No point in moving the little beasties around, or sleeping in a pile of them, either.

Doing the major clean-up and removal of contaminated materials shouldn't take more than a few days. It's basically just grunt work, delicacy is not needed, just stamina! After the moldy stuff is out, you won't have keep the rooms separated.

Finally, one other thing I should point out is that if you have any health or breathing problems, you shouldn't undertake this yourself without considering it very carefully.

I hope this isn't an overload, but useful to you. Good luck!

Molly~

PS: I find if you put a subject in the title of your post, I think you're more likely to attract answers. I have only a limited time to reply to topics, and pretty much stick to subjects where I have info to offer. A thread that just says, "please help", will not get opened opened as frequently. Sorry you didn't get a quicker response, though.

OK, I went back and hunted up your first post, so I know the answer to the foundation question.

And I see this is not your house, yet. So that makes it easier. You need to have it inspected and have several bids from remediation companies either before you make an offer or as a contingency of the contract, with them (the sellers) either letting you out (harmless) of the contract if it turns out to more than it appears, or them paying - or allowing - the cost of the remediation.

Don't be shy about asking for this, they will have to deal with it with whichever buyer appears, so if you like the house, why not you? The sale price will be depressed by the apparent, or actual damage, any way you look at it.

From my quick scan of your description it sounds like it's confined to the basement, at least for now. I think that's better if it has not risen up into the main structure (though it will, in time).

Now there is a great deal of hysteria over mold, so expect some gloominess from professionals who want to sell you a lot of remediation. That's why you need several quotes, and possibly a structural enviromental engineer to help you assess what will clean it up and solve the problem.

I am more cheered up by this, since you don't own the bulding, yet. Do your homework, and you could wind up with a solva-able problem, and very nicely priced house that you love. Or you could walk with your capital still safely in your bank accouont. So, it's a double upside for you.
I am attaching a link to a Preservation Brief on moisture control. One of a series of vey useful resources. (scroll to end of Brief to find link to other topics).

Molly~

Here is a link that might be useful: Link to Nat. Park Service Pres. Brief on Moisture Issues

Just curious why to use diluted Clorox instead of full strength Clorox?

Full strength is overkill, and increases the chance of problems from using it: fumes, spills, stains, inadvertent damage.

Ok, so have I ever used it full strength in moments of desperation? Yup! And paid the price in enduring bad fumes. It is not really safe, and uneeded, as well.

Remember you're not trying to sterilize the surfaces, just reduce the biological load.

And, if having mold isn't bad enough, I recently read a scientific paper that suggested that some molds in their latent stages are perversely stimulated by strong doses of the very things that are intended to inhibit them: Clorox, alcohol, heat, cold, reduction of humidity and exposure to Uv light.

I guess we shouldn't be surprised since molds pre-date us, and are sure to be survive after we are gone.

So I guess the most cogent reason not to use full strength Clorox is that while you are choking and gasping and ruining your clothes, the litte beasts are laughing and feeling energized. That's too much to bear!

Molly~

Full strength evaporates too quickly to do the job effectively. I believe I got that tidbit from the EPA website, but possibly elsewhere.