Wet sub floor wall and wet internal ground floor wall

[Alex H]

Photos:
https://imgur.com/gallery/Vld7A

Hi, we purchased a new house and we knew it would have some issues.

1930 concrete block 215mm thick with render construction. Timber suspended floors on concrete piers in a sub floor.

There is a cracked concrete path that runs down the side of the house, it's higher than the floor level and as such we were expecting rotten timbers on that side, surprisingly timbers are better than expected for the sub floor.

However the sub wall on the path side is a bit damp, and I'm wondering if I should try to improve that situation?

The chimney breasts extended into the sub floor, and look like they were once open to vent the sub floor, but have been bricked up, should I open those back up?

Sub floor vents, 2 front, 2 rear were partially open, but I've stripped back about ten layers of paint to open up the grooves.

I was going to lower the side path, but we have a neighbouring retaining wall and I don't think I can lower the path significantly.

Instead I was considering building an open lean-to and getting the concrete off to try and keep it dry.

Or should I excavate down the wall and put in a French drain?

I'll add a photo of the side path

 

[Alex H]

Also, as per the photos I have a wet internal column. I was expecting to see concrete block with mortar joints, but I can't see any mortar joints... Anyone seen this construction befire?

 

[Mr Chibs]

Could do with some pics please.

But if you can't remove the high path (totally), then what about chopping a trench, 150mm wide and filling with large pebbles?
I did the same, used diamond disc on large angle grinder and dug out around 150/200mm deep.

I also used dryrods in the mortar line (might not help you, depending on if your house is brick or not)
See here:
https://www.diynot.com/diy/threads/channel-drain-damp-patio-too-high.486890/#post-3963530

Should say, damp has now gone.

Airbricks/ventilation is important on older properties, I've re-instated ones blocked-up on my house. I've never seen a vent under the floor in a chimney breast, so hard to comment further.
Can you take a pic.

 

[Alex H]

I'm down again on Friday. I'll take some pictures.

I'm thinking a lean to and removing water getting anywhere near it would remove the source of water, then I can open it up and let it dry.

Thanks

 

[Adam182]

Im thinking a lean to and removing water getting anywhere near it would remove the source of water, then I can open it up and let it dry.

Thanks

If you can guarantee its from water coming from above and down as opposed to rising from below with the water table or running with the land then a lean to might go towards alleviating the issue somewhat.

Mr Chibs idea above of digging a trench and filling with clean hardcore would be my approach, I would also add the dryrods as extra precaution (recently used them myself).

You could also put some land drain in the hole before the hardcore.

The problem with your french drain idea is that you wouldn't be able to get the required depth by the sounds of it to remove all the water.

 

[Alex H]

Well, if anyone was interested I've found the source of water in 4 areas in the house and worked out how to solve most of those.

Firstly, that wet column has a gutter pointing at it with no end cap. It's soping wet and internally it's been plastered over in the past with gypsum over the lime render. Trapping moisture in. Gutter sorted and stripped back gypsum to find about a half inch of weak mix concrete render that's shot from the moisture. Remove that and blockwork is there. It's also sound and now starting to dry where it's been exposed.

Other wet wall area adjacent the path. Source of water could be the path, or the sub floor vent that is internal and let's 80percent humidity air onto that wall..

Sub floor vents opened up and humidity has fell to low 70s under the house. Timbers look good under there thankfully and I'm putting in new air bricks.

Found a water feed from tank dripping down a boxed in section, from the tank, to the back bpiler and sub floor. All ripped out and plaster removed.

Upstairs bedroom, which was a kitchen circa 40 years ago has water damage from a sink outlet. Again, plaster over the lime render trapping it. Stripped back to block and it's now dry.

This house has just suffered from poor ventilation and some bad decisions by people who have worked on it using modern materials

Fingers crossed im now happy with the structure.