Dry out basement

[AJ82]

Hello!

I have torn down framed walls and floors in my old moisture-damaged basement. Now it's bare concrete on the walls and floor. The temperature is around 20 degrees, and the humidity is 50 - 55% with a dehumidifier running. Are these adequate conditions for drying out the remaining moisture from the walls and floor, or do I need to add more heat?

The question assumes that there are no other underlying causes for the moisture problems than 50-year-old framed wood, which I hope is the case.

 

[HogeN]

depends on how the exterior is if it is drainage and protection/insulation against the stone foundation/wall.. otherwise, it's like cosmetics and you'll have to redo the same thing again within x years... BUT if it's in condition, it's no worries

But let it dry for some time if it doesn't sink more then it's just to nail in my opinion

 

[Viktor.J]

Just ensure that the room is sealed, if you have ventilation or similar open, it will be difficult to dry out. Don't know how insulation from the outside affects it, but if you don't have drainage/insulation, there might be a risk that you are constantly adding moisture to the walls as well.

 

[AJ82]

The drainage is under control and the exterior walls are moisture-protected. However, dehumidification is challenging because there is an open staircase to the upper floor. But the dehumidifier does at least reduce the moisture content from about 60% to about 50% when running at full capacity.

 

[HogeN]

The drainage is under control and the outside walls are moisture-protected. However, dehumidification is difficult because there is an open staircase to the upper floor. But the dehumidifier at least reduces the humidity level from about 60% to about 50% when running at full capacity.

Then it's good =) and if it fluctuates between 50-60%

 

[Viktor.J]

What was the purpose of drying? You write "old moisture-damaged basements" is it a newly arisen moisture damage?

 

[AJ82]

What was the purpose of drying? You write "old moisture-damaged basements," is it a newly occurring moisture damage?

These are framed wooden walls and floors that have been in place for far too long and have become rot-damaged. The concrete has then become wet because it hasn't been able to breathe.

 

[Dilato]

50-60% is dry enough, I don't have it that dry in my basement. There, it's between 67%/18.3°C and 73%/16.9°C right now and it feels completely fine.

 

[AJ82]

50-60% is dry enough, I don't have it that dry in my basement.
There it is between 67%/18.3°C and 73%/16.9°C right now and it feels quite ok.

I'm thinking that you might be able to live with a higher moisture content when everything is already dry, but that you might need to lower it to dry out what has already become damp?

 

[Dilato]

I think one might be able to live with a higher moisture content when everything is already dry, but perhaps you need to lower it to dry out what's already become damp?

I'm no expert but I believe that:

It's probably difficult to dry out more than you have, moisture moves from wet to dry so the drier you try to make the concrete floor, the more moisture it absorbs from below, and since you've said yourself that "the concrete has become wet," you probably have, like me, an uninsulated slab without a moisture barrier, so it can't be made truly "dry."

During the summer/fall of 2021, it was so damp in my basement that my stone imitation floor made of glued square plastic tiles came loose from the floor, and moving boxes became water-damaged and dissolved.
I was away from February to November and had no ventilation at all in the basement.

Now I have carpeting and a regular mat directly on the concrete floor and run a dehumidifier 15-30 minutes every night on a timer, and everything is fine.

I also have temperature & humidity meters in almost every room in the entire house, so I can keep track.

 

[jonaserik]

Hello!

I have torn down the framed walls and floors in my old moisture-damaged basement. Now it's just bare concrete on the walls and floor. The temperature is around 20 degrees, and the humidity is 50 - 55% with a dehumidifier running. Are these suitable conditions to dry out the remaining moisture from the walls and floor, or do I need to add more heat?

The question assumes there are no other underlying causes for the moisture problems than 50-year-old framed wood, which I hope is the case.

Old basement? Do you know what it looks like under the floor, if it’s directly as usual (in older houses) on the ground? One way to find out how it is, is to open the floor in a good spot. Is it rock underneath or just clay/soil/gravel, dig almost so that your arms are not enough to see if water stands in the hole.

 

[AJ82]

Old basement? Do you know what it looks like under the floor, is it laid directly as usual (in older houses) on the ground. One way to find out how it is, is to open up the floor at a good spot. Is it rock underneath or just clay/soil/gravel, dig out almost until your arms can't reach to see if water pools in the hole.

1936. Don't know what it looks like under the slab.

 

[AJ82]

I'm not an expert but I think that:

It's probably difficult to dry out more than you have already done, moisture migrates from wet to dry, so the drier you try to make it in the concrete floor the more moisture it pulls from underneath, and since you've said yourself that "the concrete has become wet," you probably have, like me, an uninsulated slab without a moisture barrier so it can't be made "dry" for real.

During the summer/fall of 2021, it was so humid in my basement that my imitation stone floor made of glued square plastic tiles came loose from the floor, and moving boxes became moisture-damaged and disintegrated.
I was away from February to November and had no ventilation at all in the basement.

Now I have a carpet and a regular mat directly on the concrete floor and run a dehumidifier for 15-30 minutes every night on a timer and everything is fine.

I also have a temperature & humidity meter in almost every room in the entire house so I can keep track.

Sounds reasonable. I also have temp and humidity monitoring, so I will notice if it gets out of hand. Now I suspect that the moisture level will decrease as it becomes more winter, but by summer the dehumidifier might need to be run again.

 

[jonaserik]

1936. Don't know what it looks like under the slab.

In 1936, there is likely a thin (about 5 - 7 cm) concrete slab directly on the underlying soil. You can hear it if you take a board and thump on the floor. If the slab is thin, it can produce a hollow sound, and if thick, a more muffled sound. You say the joists against the concrete have somewhat decayed; moisture comes through the slab and it could be because water stands a bit below. At that time, it was not customary to lay more than maybe a centimeter of sand/gravel to level for the casting, maybe even without reinforcement.