What to do with damp subfloor soil?

[chimchimfan87]

Hi Bunnings community

I am seeking some help here. I have recently purchased a house in Sydney built in the 1970s and in the building report it is mentioned that some parts of the subfloor soil under the house are a bit damp. No issues reported with the subfloor itself. In the same report, it is also mentioned that the weep holes at the front of the house are covered by soil as there is a garden bed in front of it. I am planning to rectify this and remove the soil so the weep holes are uncovered. I am wondering if uncovering the weep holes will fix the damp soil and make it dry again? Or, is there something else I should be doing? Is it normal to have some parts of the soil being moist and a little damp? I have just purchased the house and quite tight on cash at the moment. Any help on how to fix this is much appreciated.

[Dave-1]

Good Evening @chimchimfan87 

Congratulations first up!

The weep holes you mention are for air flow to help remove humidity from under the house. Id definently have this higher on my list to remove the soil and uncover the slots in the brickwork. Id also have a look around and see if there is soil next to the other sides of your brickwork. Those white stains on the bricks is from moisture traveling up (most houses have some sort of this especially built from back in the 1970's (My house does) It could take awhile to dry out even when you uncover the vents. You can also install larger grilled vents for more airflow to pass through tho I would read the next paragraph first as potential reasons why you have dampness there. (Its not scary btw )

I actually had water traveling through the brickwork (yeah there are fine cracks, wheep holes/airvents that get covered all allowing water to get in) from down my side path, when it rained the water would flow along and down the path, down between the concrete and brickwork, through the bricks and under my house... So this is what Im trying to descibe, do you have something around your house that could be doing the same type of deal? Have a think and you may be surprised what you come up with. 

My solution was to remove the concrete path (had to go as I also replaced my stormwater piping anyway) and then reinstall a new path with pavers and gravel that allowed free drainage. No more issue

Dave

[MitchellMc]

Congratulations @chimchimfan87!

Weepholes typically allow water to exit the wall cavity, so it's important that they are not blocked to ensure the wall cavity remains dry. They might not be directly related to moisture under the house, that's likely from something else.

It's not a huge concern to have damp areas under a house, but does indicate that there's potentially a drainage issue where water enters under the house in rain events. In a rain event the entire soil under my house can become wet and remain damp for quite some time.

To resolve your issue, you might only need to look at installing some brick vents, which allow airflow under the house. It's this airflow that will help dry out the soil. You issue doesn't look bad enough to resort to powered sub-floor ventilation, but that is an option if the issue persists.

Please let us know if you have any questions.

Mitchell