Mold in my vault

[Ranger Roberts]

Hello everyone, I was hoping to get some advice from everyone. Last year I built a new house. In the basement I had a "vault" room poured under the front porch. The porch is covered and is a cement slab and the vault is directly under it. The vault walls are all underground except for the wall that is in the basement. I installed a vault door in the basement. Inside the vault I have built racks for all of my long guns and I have pegboard on the walls for all of my pistols. I have a 2nd safe inside for all of my NFA items and some other misc items. There is electric inside and I have a dehumidifier running to keep it at 65% humidity.
I was in the vault last night and I noticed mold on the stocks/slings of a few rifles. Not all of them, just a few. I took a closer look around and there is mold started to grow on one of the walls. I immediately mixed a 50-50 water/vinegar solution and sprayed to wall. I wiped down the effected rifles with Rem Oil as well.
So what the heck am I doing wrong? Any tips on how to prevent this? There doesn't appear to be mold anywhere else in the basement but I have to check more in depth when I get home. Thanks everyone!

 

[MislMan]

Being in Florida I can't say I know much about underground walls but you might want to seal the walls inside your vault with one of the concrete sealers made for sealing basement walls. I believe these sealers (apply like paint but they are not paint) would keep water vapors from seeping into the vault.

 

[Walkalong]

You must have air circulation in and out of the room or mold will grow. You need air exchanges in the room. Does the A/C Heat system blow in there? Is there a return vent if it does?

65% is pretty high IMHO.

If you are dehumidifying in the room, you want the room positive, not negative, when the A/C is working.

Sealing up a room can make things worse if you don't control humidity using air exchanges and/or a dehumidifier etc.

Does the dehumidifier pump water out of the room, or do you have to empty the water reservoir?

 

[Schwing]

I agree that you must have positive pressure in the room. I also agree that 65% humidity is pretty high. I live in a desert so it is easy for me to say this but I think anything over say 40-45% is too high.

 

[edwardware]

I dehumidify my basement to 50%, and never have a problem. Previous owners failed to do so, and grew mold.

I'd set the dh to 50%, and wait on the rest.

 

[Ranger Roberts]

You must have air circulation in and out of the room or mold will grow. You need air exchanges in the room. Does the A/C Heat system blow in there? Is there a return vent if it does?

The system does not blow in there and there isn't a return vent. It is pretty much completely sealed to the outside world with the exception of the hole for the electric and the hole for the dehumidifier pump line.

Are you suggesting that I cut a hole in the concrete to increase air circulation? I have access to a core drill. Or should I just start by lowering the humidity?

 

[Sniper66]

I just had my furnace and humidifier repaired today and the technician said Kansas humidity should run around 35%. Not sure that is correct, but I am sure that 65% is too high. As others have said, air circulation and humidity are critical factors.

 

[Walkalong]

The system does not blow in there and there isn't a return vent. It is pretty much completely sealed to the outside world with the exception of the hole for the electric and the hole for the dehumidifier pump line.

Are you suggesting that I cut a hole in the concrete to increase air circulation? I have access to a core drill. Or should I just start by lowering the humidity?

Well,, since air circulation would be difficult now, I would start by lowering the humidity setting.

If that isn't enough, it would require two small holes if the space doesn't leak air at all.

I would think that in an enclosed space like this it should be easy enough for the dehumidifier to do the job.

 

[Sour Kraut]

You must have ventilation (air exchange) and 65% is too high for your room. I just had mold remediation performed in my attic and needed to increase the ventilation. The mold remediation company gives a 5 year guarantee on the remediation but ONLY if the humidity remains below 55-60%.

I think you have some work to do but you should be able to control the environment in that space. Good luck, and let us know what steps you took to solve the problem!

 

[Ranger Roberts]

Thanks guys! I will change the dehumidifier tonight when I get home from work. I will let ya'll know how it works out.

 

[another pake]

Basements tend to be cool. At 65 degrees and 65% RH you are nearing the saturation point of the air as far as moisture is concerned. It will condense and cause you problems.

Warm up the air, lower the humidity and get some air moving. Fans and moving air alone won't do much if anything. The air is still near saturation.

 

[eddd7]

Where does that catch basin of your dehumidifier drain into? If it doesn't frain outside the vault, that's your problem. Also, lowering the moisture level in your vault actually encourages water vapor to migrate through the concrete.

Years ago I sprayed the walls and floor of our basement with Radonseal, which penetrates the concrete, fills the air spaces, and hardens. Concrete passes water vapor really well, as it's supposedly 17% air. You apply the Radonseal with a garden/bug sprayer so it goes on quickly. It works very well. Our basement is dry with no mold.

 

[a1abdj]

"Fixing" these types of problems are usually much more difficult that simply doing it right during the construction process. If you consulted with a "professional", I would get them out there to rectify their problem.

 

[CB900F]

Ranger;

The problem with air circulation is that it's also a path for fire, or the gasses produced by a fire, to get into the vault room. Yes, do lower the humidity, use a high-temp RTV to seal the conduit(s) bringing electricity into the room, and start thinking about air circulation as well as your ground water.

Was the exterior of the foundation sealed after it was poured? Was the pad poured on a water barrier? If not, then sealing the interior of the walls may help, possibly a great deal. However, as I understand it, a lot depends on the product used & proper application. If you do introduce holes, or ducting, into the room, you'll also need to provide for a temperature sensitive method of sealing the duct from being an open pathway for fire & gas. The noxious gasses from a fire can absolutely ruin scope coatings, stamp collections, photo's, and other important items in the vault room.

900F

 

[cdk8]

I'm with CB900F in my curiosity regarding what curing and/or sealing was used, and if the shelving hardware is drilled into the concrete. I've drilled into concrete and was surprised how much some bolts affected humidity without corrective action. In that same house, it also had an issue with groundwater management, and I think that amplified what I experienced.

Do you have multiple humidity meters to validate the thermostat on the dehumidifier is accurate? Have you placed them in different areas to see if a single area is much higher than the others?

Does the porch have provisions to mitigate the damage from thermal expansion?

 

[Sunray]

"...mold started to grow on one of the walls..." Means a dehumidifier isn't enough. Any heat going in there? Suspect the room is cold and damp. Doesn't take a lot of heat to raise the temperature enough to stop molding. Mind you, I'm in a very warm 1 BR Apt and have mold forming on a spot on the ceiling of an outside wall. Suspect the balcony above is cracked and leaking into my place.

 

[au_prospector]

I assume your concrete walls are below grade. They will wick in moisture and need to be sealed.

Add air circulation and lower dehumidifier to 40% and see if it keeps up.

 

[HighExpert]

A fan will help. Get a good quality oscillating fan, put in on a timer to run about 12 hrs. a day and I think you will be good. I would get the humidity below 50% and sealing the walls and floor is not a bad idea. Concrete sweats.

 

[dragon813gt]

I just had my furnace and humidifier repaired today and the technician said Kansas humidity should run around 35%. Not sure that is correct, but I am sure that 65% is too high. As others have said, air circulation and humidity are critical factors.

I'm assuming he was talking about the humidity set point for the humidifier. This is the comfort range for most people when they're running their heaters in the winter.

65% is way to high of a set point. You wan to keep it at 50% or slightly below. The lower you set it the warmer it will make the room which may or may not be a problem. Depending on how the structure was built you may not be able to drop it below 50% w/out the dehumidifier running constantly. Hopefully you have a proper vapor barrier.

 

[BSA1]

R.R.,

I have the exact same kind of vault room in my house.

The temperature is usually 70 degrees in the summer. In the winter I run a space heater and try to have a average temperature of 65 degrees. Average year round humidity is about 50%.

When my house was built they sealed the outside walls of the basement with a black tar.

On the inside of vault walls I painted two coats of latex BIN sealer. Concrete is rough and soaks up the moisture in the paint so I put on two coats with a rough surface roller to get into the little pores. It takes a lot of paint to get into all of the little pores in the surface of the concrete. It basically inhales the first coat!

I have a small water leak in the corner of the ceiling from the keylock they made when they poured the porch. I keep the leak sealed with clear chalking on the top of the porch. On the inside of the vault I painted the ceiling and the water leak with a water proof concrete paint. Again I applied in two coats with a rough roller to get into the pores.

Since then I have never had anymore water drips. In addition the white BIN sealer and the waterproof sealer have made the inside of the vault really bright. My vault is 15 years old when no signs of the paint wanting to peel and no mold.

I like to keep the vault in 65 - 70 degree range as I store my ammunition and gunpowder in it along with my guns and lot of other stuff.

 

[CapnMac]

Vault spaces meant to be isolated from their "parent" spaces need to have their own dedicated ventilation. In many climates that means such space will require their own conditioning, too.

The climate will then determine the make up of conditioning parts, like heat recovery vents and the like.

Vaults do not need many airchanges per hour, but they do require some. This is further complicated if the vault space has any additional uses, such as a severe storm shelter or the like. You take a vault which has almost no discernible heat gains, and you ad a person, that person, sitting still is adding 350 BTU per hour of direct heat, and 350 in latent heat (body-heated humidity increase).

All of which should have been considered in the design before construction.

 

[rondog]

JMHO, but if you can afford to build a new house with a built-in vault, I think you could afford to bring in a pro for a consult and modifications instead of trying to figure it out yourself. There's too much at stake. Some things just shouldn't be DIY, IMO.

 

[BSA1]

Opening the vault door frequently will allow for air exchange. I try to open my vault and leave it open for a couple of hours several times a week.

 

[kudu]

If setting the humidity to 50% works, great, if not you said you have access to a core drill. I would core 2 holes, one high and one low at opposite ends of the vault. You could go with 3" and install a computer cooling fan to run all the time, or 4" and duct heat in from a forced air system, assuming you have a forced air system and not boiler heat. The second hole is for exhausting air being forced in.

If fire is a worry with having the holes, set up a steel slide gate on a lead link made with cerrosafe that will drop to seal the hole when the temperature reaches melting point, that will keep combustion air out of the vault.

 

[BigBore45]

Stagnant air and exposed cement is going to mold. If you do not want holes in it from the outside then the cement needs to be sealed via a paint on like kilz cement sealer. Also some sort of air movement across a UV filter would help tremendously. Also set the dehumidifier to 35%-40%. That's just my opinion. I do have 11 years HVAC experience and a safe in my basement. YMMV