Is this pressure treated 70s?

[Jonatan79]

Thank you for the response! I will take a sample for analysis. The soil in the crawl space was damp. I have dug out under half. Water has found its way in via the rock from two directions. But I have addressed that. Probably there is not much moisture damage in the floor joists, but enough moisture to cause a smell from pentachlorophenol. Two other experts have also been here and felt that it smells typically like that.
We also had a mold detection dog here that did not indicate mold in the extension but at a previous entrance in the house where there was an old hidden concrete staircase directly against the sill. That has been addressed with the replacement of the sill and crushed staircase.

Good, investigate thoroughly before you fall into someone’s “trap” and spend unnecessary money.

 

[Per Kronlid]

Bring in more professional opinions. Anticimex might be right. But they "always" suggest dehumidifiers, which they sell themselves. There are members here who were advised to install dehumidifiers under the foundation, which was a concrete slab on the ground...

We had neighbors who were deceived into installing a dehumidifier in their crawl space with a concrete slab before selling...

I am now leaning more towards tearing up the floor and replacing the floor joists. I will take a sample first. Then perhaps a proper sealing of the crawl space and installation of a dehumidifier. Thanks for the input!

 

[plåtrickard]

Bring in more professional opinions. Anticimex may be right. But they "always" suggest dehumidifiers, which they sell themselves. There are members here who received suggestions for dehumidifiers under the foundation, which was a concrete slab on the ground...

We had neighbors who were deceived into installing dehumidifiers in their crawl space with a concrete slab before selling...

I agree..
I do wonder about everyone who installs dehumidifiers both in the attic and crawl space.
You would need to close all air supply, otherwise, it's mostly the electricity companies that benefit from such a setup, right?
As long as you supply outdoor air, it will work continuously?
And how did it function without dehumidifiers all these years before?

 

[Per Kronlid]

Agree..
I do wonder about everyone who installs dehumidifiers both in the attic and crawl space.
You would need to seal off all air supply, otherwise it's mostly the electricity companies profiting from that, right?
As long as outdoor air is supplied, it will work all the time?
And how did it work without dehumidifiers all these years before?

Even Anticimex says exactly this, that the space must be carefully sealed first. Otherwise, it's money wasted.

 

[plåtrickard]

But what in the house has changed so that the need for a dehumidifier exists?

 

[MekPappa]

Even Anticimex says just that, meaning that the space must be thoroughly sealed first. Otherwise, it's a waste of money.

Exactly, you have to close off the ventilation. My crawl space rose about 4 degrees just by closing it, and with the dehumidifier, it now maintains about 16-19 degrees there depending on the season. This means I save on heating costs in winter. Of course, there are different conditions for every house. In my case, there's standing height in half as it is a split-level.

I would suggest trying to find as much of the source as possible and replace what you can. Then, with a sorption dehumidifier, there would be a slight negative pressure that makes it harder for the smell to travel up. You can also add an exhaust fan. This is assuming the smell comes from the crawl space. Take some samples in different freezer bags and smell after a few hours. I asked my colleagues for help since I live in the house and might have tricked my nose. In the end, I sent to a lab anyway.

It could also be that they used whatever was available when they built, so some planks might be treated while others aren't.

 

[MekPappa]

But what in the house has changed so that the need for a dehumidifier exists?

What has changed is the mindset. One doesn't want to live with moisture damage or odors that get into just about everything.

 

[Per Kronlid]

But what in the house has changed so that the need for a dehumidifier exists?

Good question. There should now be less need for a dehumidifier because I've managed to stop water from coming in through the rock that partially slopes toward the foundation. I have drilled and cracked the rock and made a channel along the foundation that leads the water away. I noticed this problem when I dug away soil down to the rock for the terrace/patio.
So, replacing the floor joists is probably what I should do. But as mentioned, I will take a sample first to be sure that's where the smell is coming from.

 

[ati]

But what in the house has changed so that the need for a dehumidifier exists?

Climate changes can also be the straw that broke the camel's back.

 

[plåtrickard]

Climate change can also be the last straw that broke the camel's back

But is it that much more humid in the air?
Because the drainage should take care of the soil moisture.
If moisture reaches the foundation, then that's a problem to solve first....
From a heat perspective, I can understand...

 

[MekPappa]

But is it that much more humid in the air?
The drainage should take care of the ground moisture, right?
If the moisture reaches the foundation, then that's a problem to solve first...
From a heat perspective, I can understand..

Partly, it's about correcting poor constructions from the past, but there are also many different reasons. A few might be a generational shift that doesn't accept the smell, an upgraded heating system (perhaps used to burn oil, etc. that dried things out), switched to tighter windows/doors, additional insulation, etc., which have changed the conditions for the foundation.

 

[Per Kronlid]

What is the best way to seal some gaps between the base plate and the masonry foundation? I want something that won't cause the base plate to rot, and something that won't smell in the future. Tips are welcome.

 

[MekPappa]

How do you best seal some gaps between the sill and the masonry foundation? I want something that won't cause the sill to rot and won't smell in the future. Tips are welcome.

A bit of a late reply. Not sure if you're already done. I sealed the old fresh air vents with foam sealant.

 

[MirsadRexhepi]

Hello. I am interested in knowing if ozone treatment helped? Please explain as well as you can.

We live in a house from '72 with a crawl space and pressure-treated sill plate. The house has always been without a dehumidifier. When we bought the house, we did a comprehensive interior renovation. We did not remove the sill plate but cleared the foundation, sealed it, added plastic, and installed a Corroventa CTR 300TT2 with negative pressure. Additionally, we installed an HRV system. Now the smell doesn't stick to the clothes, but I wonder as mentioned if an ozone treatment would help further.

Regards,
MIRRE

 

[klaskarlsson]

Hello. I'm interested to know if Ozone treatment helped? Please explain as best as you can.

We live in a house from '72 with a crawl space with treated sill. The house has stood without a dehumidifier for all these years. When we bought the house, we did an extensive interior renovation. We didn't remove the sill but cleaned the crawl space, sealed, plasticized, and installed Corroventa CTR 300TT2 with negative pressure. Additionally, we installed FTX. Now, the smell doesn't stick to the clothes, but I wonder as mentioned if Ozone treatment helps further.

Best regards
MIRRE

Ozone helps to remove surface contaminants and odor.
If it's something more fundamental, the smell will creep back again after a while.