Musty, Humid Basement (subfloor, dehumidifier, foundation, furnace)

[BucsLose]

I recently purchased a home built in the 1950's. I am in the process of doing something with the basement. I want to eventually finish it myself and realize it will be a long process.

Sorry this post may be a bit hard to follow. I will try not to bounce all over the place. Note that I will provide link to pictures later tonight.

Right now, the basement has a very musty smell and a bit humid. While I have yet to see any actual standing water, there are damp spots on the floor/bottom of the walls in the corner. Nearly around the entire basement, in the floor area next to walls, the concrete if hollow. I believe this use to be used for drainage. Some of this hollow area has small holes. Also with this, the blower for the furnace/ac, the drain that takes the water from the air, goes down into the concrete floor.
I also have a Radon system installed due to radon presence. When you walk down to the basement, you can hear the suction/vacuum due to the holes in the floor.

Some of my main questions:

1. Since, ever after several hard rains, I have yet to see standing water, is it safe to assume that I dont have some sort of huge problem with water entering from the outside?

2. The damp spots. Im guessing its primarily humidity dealing with the hollow floor, the holes, and even the drain from the furnace. Is the following a good course of action:

My current plan is to:

a) reroute the drain along the wall, directly to where the sump pump is. There is a drain pipe for a sink, I intend to tap into for this. Therefore, getting rid of that drain running under the basement.

b) Along all the floor area next to and including the bottom wall, I intend to scrape off the old paint, clean up/kill any mildew/mold. On the wall portion, I plan to paint on drylock. On the floor portion, where it is hollow, I intend to fill any holes, as well as add a inch layer of new concrete to the floor.

c) The ventilation ducts for the ac/heat system are not insulated. Not sure if this plays any part into the musty smell or moisture/humidity in the basement. But I plan to insulate all ducts properly.

Is there anything else that I am missing? Is what I plan to do, could it cause any problems, specifically the sealing of the holes in the hollow part of the floor and adding a thin layer of new concrete to it? Are there any other things I should do along with this before I start insulating and framing out the basement for finishing?

Sorry for the long post. If there is anything I need to be more specific or add on, please let me know. I will post pics in case they may be helpful, later tonight.

Thanks

[Coldjensens]

Some of my main questions:

1. Since, ever after several hard rains, I have yet to see standing water, is it safe to assume that I dont have some sort of huge problem with water entering from the outside?

No.

Water entry is not always directly related to rainfall. Even though it just rained, your grondwater levels may be low. You should have a drainage system around and under your basement with a sump pit and pump to take the water awate from your house. Without this, I would not try to finish the basement. You cannot "waterproof your basement iwth any permanence. You have to get the water away from your basement walls and footings. Otherwise it is just a matter of time before you will have water penetration again.

2. The damp spots. Im guessing its primarily humidity dealing with the hollow floor, the holes, and even the drain from the furnace. Is the following a good course of action:

My current plan is to:

a) reroute the drain along the wall, directly to where the sump pump is. There is a drain pipe for a sink, I intend to tap into for this. Therefore, getting rid of that drain running under the basement.

Ah ha. You do have a sump pump. That means that you probably have a drainage system. Congratualtions. If it is working prooperly, you should have no water penetration, however we have a very nice drainage system that is apparently working yet after several years, we suddenly have water comming into the basement.

b) Along all the floor area next to and including the bottom wall, I intend to scrape off the old paint, clean up/kill any mildew/mold. On the wall portion, I plan to paint on drylock. On the floor portion, where it is hollow, I intend to fill any holes, as well as add a inch layer of new concrete to the floor.

That is all fine but you cannot make your basement into a boat. You will never permanently seal every possible entry point for water.

c) The ventilation ducts for the ac/heat system are not insulated. Not sure if this plays any part into the musty smell or moisture/humidity in the basement. But I plan to insulate all ducts properly.

There is a product that is like a squished pipe with drain holes in it. It is made to sit on top of your footings and collect the water there. If you thinnk that you have water penetration, I would have them jackhammer up the basement floor and put this system in. Had we known about this system we could have had it don for less than $10,000. Now we are looking at tearing out our entire finished basement and putting the system in at a cost of more than $50,000. Do it now. Save money later.


Also I would suggest that you use some form of subflooring that leaves an air space beneaththe subfloor. This is important both for insualtion purposes (avoid cold floors) and to allow air circulation to dry out any water or dampness that gets in. It will also allow a flood in the basement to run under the floor without damaging anything (as long as it is not too deep). Further, I would use only treated lumber or better yet some form of plastic materials on the bottom of your walls. Use plastic mouldings and wall panels as well (not drywall). That way if you do get water, you will not have to tear out walls to replace them.

[chet everett]

There are many things that MIGHT be going on with this older home, but without being there in the flesh the "clues" are easy misread.

Even the simple stuff, like rerouting the condensate drain MIGHT be an an improvement OR risk making things worse / mask true "root of your problems"... Generally the condensate drain from the HVAC only puts out a small amount moisture. If the ducts are not well sealed, if the house has other humidity issues or if the HVAC system is not opersting properly (and that could include a stopped up condensate drain...) you can get both excess moisture attempting to be removed and some horrendous stink moving around! Even if everything else is OK, movingmthe condensate drain into an existing sanity sewer line is a bad idea and probably agiainst code unless you do at height above the trap, and they might require a condensate pump -- among the most failure prone inexpensive bits in many A/C setups...

The "holes" many in fact be a designed in "weeping drain" that if properly connected to an appropriate sump pit and pump ought to save you from having a catastrophic hydaullic failure of the walls during torrential rain -- do not mess with such a system unless you know EXACTLY what you are doing!

Ditto the "drylock" -- in poor soil conditions with the wrong kind of foundation the application of an interior based sealant can hasten the destruction of the foundation and create a structural issue. Generally that combination of things is too remote possibility to worry about, but if you do not know with certainity that there is nothing to be concerned about, why risk it?

Before I would give any thought to finishing a basement that has ANY signs of dampness or mustiness I would spend some serious time talking to professional contractors and engineers that will seek the true source of these problems, systematically address them, fully document the entire diagnosis and remediation. Then and only then would I contemplate finishing the space. Having suffered through a basement or two that took on as much as 18 inches of water I fully endorse the suggestions to build it out with an eye toward protection. The money spent on prudent measures to deal with with water AND the appropriate backup to guard against loss of power ought to be number one budget item AFTER the analysis and remediation outlined above is undertaken!

[BucsLose]

I just wanted to add some pictures just in case they might help.

HomeBasement pictures by Molsenx - Photobucket

chet, I think the holes in the section near the storm door may have been intentional at one time.
Maybe they used it for when rain may have came in from that door back in the day. As of now, rain does not come in through there.


I am thinking about getting a pro to look at it. But honestly, I am trying to save some money, even if it means getting down and dirty and busting my butt to do it myself. Im not sure if I could hire someone just to give me an assessment on what exactly should be done.

[maf763]

Have you looked at the drainage outside the house, especially where the damp areas are? You might have water gathering at the foundation.

[sgresident]

go out and purchase a dehumidifier right NOW! also, get a humidistat thing to let you know exactly what the humidity level actually is. get the number down below 50. a good range is between 40 and 50. definitely under 60. this may make a huge difference right off the bat. If not, then get someone in to do some inspecting.

[BucsLose]

maf,

I am definately going to change the down spouts and some areas around the perimeter could be higher. So Ill add some dirt and taper it off as it goes away from the house.
Next time it rains, Ill take a look at home much water gathers around the foundation.

sgresident,

I did look briefly into dehumidifiers. I havent picked one out yet because it seems like there is always a negative to one of them. Ill have to continue my research. Im guessing people still use dehumidifiers even after they finish a basement? Eventually Id like to finish it, but Ive got a lot of work to do first.

I still plan to tear off the paint to the bottom portion of the walls and the floor areas near the walls. Clean them, and coat the walls with drylock or something similar. And put a layer of hydraulic concrete on the floor as well as covering up the holes. This I believe will not only help the dampness in those areas but the concrete filling of the holes, I would think would make the Radon exhaust work better for the area under the basement floor. Not only in getting the Radon, but possibly help with the moisture.