Last summer we bought an interior townhouse (built in 1972) which has an unfinished basement with exposed cinder block walls. We haven't had water in the basement, but I've recently discovered mold growing on one wall. Initially I had mold remediation companies come out, but one suggested that what I really needed to do was fix the problem causing the mold -- water in the block walls.

We've had 4 different companies here who have all recommended their version of an interior drainage system with a trench, pipe, sump pump, etc. But after reading the posts here I'm not sure that is the best decision.

I completely understand that fixing the problem from the outside is the only true fix. But, we will only be in the house for another few years & the cost of digging up the exterior (and replacing the gorgeous flagstone patio we have) plus having to dig up part of our neighbor's back yard (because part of our wall is on their side of the fence) isn't something we'd prefer to do.

Are interior drainage systems always a bad thing? Are any of these companies reputable? Each company is saying their materials/approach is the best (and dissing the competitors too) -- how do I know which is the best choice for us? Is there a best practices when it comes to these drainage systems?

I'm completely confused.

I'm afraid I don't understand your confusion. If the problem is moisture in the wall, the only true fix is to keep the moisture out, anything else is just cosmetic.

Since it is just the one wall causing problems, is it the same wall that runs into your neighbor's yard and also backs up the patio?

Is it possibly an issue with run-off that could be diverted and dealt with before it gets to the wall?

What's the confusion? Will an interior drainage system keep water out of your walls? Will it prevent mold? The answer to both questions is NO. The mold people were right...until you deal with the problem of water entering your walls, the mold problem can't be cured. The one and only place to deal with water entering foundation walls is where it enters...outside. Unless you'd rather be one of the dozens with unsatisfied complaints to BBB, and out many thousands more dollars than it would take to fix the problem from the outside.

How do you know you had mold?
Cement block walls do not support mold growth.
While the dust that collects on the surface will. Its simply a matter of cleaning the cement. It’s been said many times. Three things are needed to grow mold. Oxygen. Food source and moisture. Cement is not a food source.

What I think you had. was the white powdery material growing out near the bottom of the block. This is efflorescence not mold. This is caused by water within the wall dissolving the salts within the cement. As the water evaps out on the surface of the basement side it leaves this deposit as a white power. A host of water proofing companies fool people into thinking its mold.
To answer your question about the interior/exterior issue. No interior systems are not bad, they just do not solve the real problem. They simply control (most of the time) the water that is entering from a crack or opening on the outside of the wall. They do not fix the problem.
So you could get away with in interior water control system but do not believe it’s the cure. It’s only a control.
In choosing a water proofing company you need to really check around. BB boards, is a good place to start. Also compare prices. You’re going to get a real range of prices to do what is really a simple job, just a little back breaking. Be sure their licensed in your state if it’s a requirement. Insured. Get copy of cert.

Now for a wrench in the works.
If it’s a townhouse. Is it a Fee Simple mortgage? Meaning do you own the outside of the home? Who is responsible for the sidewalks, shrubs, roof replacement etc? If its the association then get them to fix the water issue. AS it’s their responsibility to prevent water from entering into your home. Let them worry about the walks shrubs neighbors etc.
Why should you attempt to fix something that is not your responsibility?
Also you may not be able to do this without their permission. AS the floor and basement walls are considered common areas, you may not be allowed to touch them without their permission anyway. Check your bi-laws

I'm confused because I know many people with sump pump drainage systems (I also grew up in a house that had one) & I never thought they were a bad thing until I started reading the responses on this message board. Did all these people make the wrong choice?

I fully understand that the drainage system isn't a cure to the water. As I understand it, it manages the water flow. Maybe I was misinformed, but I was told that stagnent water in the block makes the walls damp & the combination of dust from items stacked against the block wall (or the items themselves) causes the mold to grow. If the water flows through it doesn't allow the mold to grow.

Honestly I don't know for sure if it is mold as it hasn't been tested. But, it's black & splotchy & looks exactly like the pictures I've seen online. There is also some efflorescence, but it is different from what I'm thinking is mold. The mold people have said it was mold, but without testing it.

I'll check my HOA bi-laws about the exterior walls. I've already talked to my HOA president & he said many, many residents have had sump pumps installed.

quote:

Did all these people make the wrong choice

In a word, yes. An inside drainage system is only a water diversion system. It can't stop the water from coming in, it can't stop mold growth, it can't stop the entry of insects and vermin, and it can't stop the entry of radon gas.

Often a sump pump is installed to handle water from an outside french drain system, or as a safety factor when a building is in an area with a high water table. It is nere intended to, nor able to, stop water from entering foundation walls.

Few more thoughts.
Just because it looks like mold does not mean it is. If the walls were painted at any time then what your seeing is the stains left over by the water seeping through the block. It could have some mold on the paint as that can be a source of food in which the mold will grow. However it is very rare that the mold present contains enough spores to worry that you need a professional needs to clean it. Just clean with bleach and water.

Now for the real battle your faced with.
Just because everyone else has had pumps installed in their units does not mean that you should do that as well. The HOA president is not looking out for your best interest. I have seen this time and time again. Read your bi-laws and if you do not understand them get an attorny to read them for you. Draft a letter to the assocation and tell them to fix the water issue. Ask for a written response back not just talk. Almost all of the bi-laws that I have seen make it the resonsiblity of the assocation to fix water intrusion within the home. The other owners may have been lead down the wrong path by them hearing that its their problem not the HOA. Remember your in uncharted waters sort of speak, no pun intended. If you suceed in getting the HOA to fix your basement then everyone else that has issues will want it done. Its the managements job not to spend money so they are going to fight you. As this will end up costing a lot.

You already understand that a interior sump pump system only controls the water after it comes into the building. It may appear that the walls are dryer after the system is installed, but all you have done is moved the water to below the slab and out of the walls. Which can cause more issues such as damp floors, smells as the underlying soil will become damp from the water thus more mold growth. Stagnet water in the block is also not a good thing either.
A interior system is only a band-aid not a cure. Do all that you can to have the outside fixed. Your not going to see any increased value in your home if you do the repair on the inside, so why not push the HOA to fix this once and forall. Based on your conversation it sounds like a lot of folks need this done anyway. Get them involved. They as well as you are paying for the maintenance of the buildings and grounds.

Yes, interior systems are water control. In fact, there is no true way to really "water proof" any existing structure. Often it becomes non-feasible to excavate a structure and apply any kind of material of barrier. If it can be done, it is a good option. However, I'm personally not a big fan of it because disturbed soil takes on more water because it takes years to resettle and essentially creates a funnel right to your foundation walls.

My company installs both interior and exterior water control systems. We are also a foundation repair company, so we approach water from a structural mindset, which is a bit different than the average waterproofer. Interior systems are not bad. Ideally, the best scenario would be to construct with systems on both positive and negative side of the wall.

You have to always consider all factors involved, including soil conditions, age of structure, footing configuration, the homeowner's goals for that space, grade, downspouts, proximity to bodies of water or water tables,etc. when determining where best to address the problem. To control mold, you have to control humidity and moisture. Also, a closed drainage (visit www.gratedrain.blogspot.com) system will not allow bugs, gases, radon, etc to come into the basement, and they don't displace the water.

Also, an exterior application will not rememdy excess water under the slab...