Basement concrete drying?

Two weeks ago, I had a sewage backup in my basement. Plumber fixed issue, and damage mitigation service pulled up carpet/padding, steam cleaned and sanitized all surfaces, including the bare concrete floor. Probably 100-150 sq ft total...so it didn't even affect our whole basement. They left 4 huge fans and a giant dehumidifier down there for 5 days to dry everything up.

Fast forward to today. It's been a week since damage mitigation finished (so 12 days after the incident), and the concrete still looks wet in many spots. It looks like water seeped down into tiny hairline cracks in the concrete and although the surface feels dry, it still looks wet.

I have carpet people coming in 6 days. How do I get the concrete completely dried out before they install new padding/carpet? Or is it considered dry enough at this point for carpet since the surface feels dry?

Thanks in advance!

Put some fans down there , and a dehumidifier.

Can you check the humidity level down there. Id does look damp. I doubt those hairline cracks could hold much water. Did that large dehumidifier drain into a tub or shower, or have a container that needed to be emptied? If I had a container, how often was it emptied?
How about your location, recent weather and outside temperatures? Just curious the normal outside humidity levels.
I'd think 5 days with fans alone would have dried the floor pretty well if the heat was on.

highup said:

Can you check the humidity level down there. Id does look damp. I doubt those hairline cracks could hold much water. Did that large dehumidifier drain into a tub or shower, or have a container that needed to be emptied? If I had a container, how often was it emptied?
How about your location, recent weather and outside temperatures? Just curious the normal outside humidity levels.
I'd think 5 days with fans alone would have dried the floor pretty well if the heat was on.

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The dehumidifier drained into my sump pump pit. I live in Kentucky and this time of year the outdoor weather has been 70-80 throughout the day with high humidity and lots of rain. AC has been on in the house due to the higher temps outside. That may be why this isn't drying as fast as normal.

I may have to delay carpet installation at this point until the concrete is no longer damp.

Smart Move . You can do a Matt test to see if moisture is still coming up .

take a 1' square of clear plastic and tape it to the floor . check it in 24 hrs.

If you see condensation under it you know you are still gassing off moisture .

It is not a exact science, But it will give you some indication it is still wet .

Nick said:

Smart Move . You can do a Matt test to see if moisture is still coming up .

take a 1' square of clear plastic and tape it to the floor . check it in 24 hrs.

If you see condensation under it you know you are still gassing off moisture .

It is not a exact science, But it will give you some indication it is still wet .

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Use some thick plastic sheeting, not that cheap, thin .00000004mil painters plastic.
Be sure it has no holes or punctures and tape the edges down as good as you can so there is no air getting in or out.
I'd go for 3' by 3' Nick. ......even tho this one's a no brainer.

Slip of the index finger Hi.

Nick said:

Slip of the index finger Hi.

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Better than the middle one.

highup said:

Better than the middle one.

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He only types with one finger.

Yes , My trigger finger !!

Baby powder----works like magic and let's face it----other things smell worse

rugaddict said:

Baby powder----works like magic and let's face it----other things smell worse

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Does that really work? And are there any downsides to using baby powder other than the smell?

I was able to borrow a 30 pint dehumidifier and rented some carpet fans from home depot. They're all running constantly in the basement now at hi speed. Hopefully that'll take care of the remaining dampness but baby powder might be my hail mary play. I just can't believe how long it's taking for this concrete to completely dry up!

In your initial description, you mentioned they applied a sanitizer. Any chances that this sanitizer has left a residue and that the concrete is simply discolored but actually dry?
How long was the floor wet? This has been like 3 weeks since the old carpet was removed?

highup said:

In your initial description, you mentioned they applied a sanitizer. Any chances that this sanitizer has left a residue and that the concrete is simply discolored but actually dry?
How long was the floor wet? This has been like 3 weeks since the old carpet was removed?

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The floor was wet for about 48 hours before everything got cleaned up. It has been nearly 3 weeks at this point since the cleanup happened and the floor was steam cleaned and sanitized.

I didn't think about the sanitizer discoloring the floor. I think that's very possible, especially since it really only appears to look damp in spots where water/sanitizer went down into the tiny hairline cracks of the concrete.

When I checked the dehumidifier this morning it had a humidity reading of 35% after running for a little over 12 hours. That seems like the basement is pretty dry to me.

spke711 said:

The floor was wet for about 48 hours before everything got cleaned up. It has been nearly 3 weeks at this point since the cleanup happened and the floor was steam cleaned and sanitized.

I didn't think about the sanitizer discoloring the floor. I think that's very possible, especially since it really only appears to look damp in spots where water/sanitizer went down into the tiny hairline cracks of the concrete.

When I checked the dehumidifier this morning it had a humidity reading of 35% after running for a little over 12 hours. That seems like the basement is pretty dry to me.

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That idea just now occurred to me.

Take a close look at the miters in the door trim molding and see if it looks like there is recent movement/shrinkage. If so, the dehumidifier is doing a good job.
Are you able to shut doors downstairs so the dehumidifier is only working on the rooms involved? Otherwise it's dehumidifying the whole house.

highup said:

That idea just now occurred to me.

Take a close look at the miters in the door trim molding and see if it looks like there is recent movement/shrinkage. If so, the dehumidifier is doing a good job.
Are you able to shut doors downstairs so the dehumidifier is only working on the rooms involved? Otherwise it's dehumidifying the whole house.

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I'll check the miters when I get home today. I do have all doors shutoff to the basement. Going on day 3 of fans + dehumidifier (well day 8 if you count the 5 days that the damage mitigation service ran their fans and dehumidifier) and not seeing much of a change in the concrete. Which makes me believe even more that the sanitizer seeped into the small cracks and just discolored it.

At the rate you're going the dirt under the house is probably dry.
My hunch is the concrete is dryer than it was before the flood.........
How much water per day is that dehumidifier creating? ...and how many sq feet of room area are we talking about?
Can you call the restoration company and ask them about the discoloration and maybe about the sanitizer product's name? Then you can call the manufacturer and tell them what's going on.

highup said:

At the rate you're going the dirt under the house is probably dry.
My hunch is the concrete is dryer than it was before the flood.........
How much water per day is that dehumidifier creating? ...and how many sq feet of room area are we talking about?
Can you call the restoration company and ask them about the discoloration and maybe about the sanitizer product's name? Then you can call the manufacturer and tell them what's going on.

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The dehumidifier is pulling about 30 pints of water every 20-24 hours. This is within probably 400-500 sq ft of basement. Talking to other people who run dehumidifiers in their basements, this sounds normal. It's very humid/rainy this time of year where I live in Kentucky.

Great advice on talking to the manufacturer about discoloration with the sanitizer used. I'll get the name of the sanitizer and try to give them a call sometime this week.

At this point I'm moving forward with carpet installation. Finally getting my basement back to normal soon!

One thing to note. If there's no moisture barrier under the slab, then moisture will always be drawn upwards unless the humidity in the house is higher than the dirt below. If it's warmer and dryer inside the home, moisture will always migrate into the living space. SO if there was no moisture issues with the carpet and pad before the flood, nothing much can be different now. You're probably safe with that install.