Damp walls problems (Ed.)

[Reno104]

we’re having a nightmare with damp at the moment while renovating . Already had a damp course but the root cause (apparently) has only just been discovered. Just looking for other people’s opinions on how to handle this.

So basically we’ve been told that the reason the soil/ground under our house is wet is because rain is running down the external wall of the house and collecting at the bottom. Along the house we have slate but underneath it’s literally just earth/ soil/dirt. So his explanation is that the soil is just soaking up all the rain that’s sat against the house causing it so spread to underneath the house and to the internal brickwork. I guess what he’s saying does make sense as we’ve had lots of rain recently, but he’s told us to dig out all the slate and pour concrete against the house. Is this a good idea?

My worry is that the water will still be sat against the house it just won’t be able to soak through to the foundations.

I’ll attach some pictures for reference. How would you go about solving the issue? My thoughts were if we concrete it surely we still need to fit some sort of drainage system to carry water away from the house?

Any advice welcome!

 

[Ivor Windybottom]

Dig some chippings out completely, as deep as you can get, in a few different places. You'll need a narrow trowel, cutlery or a caking serving knife that you don't care about.

If it fills up the next time it rains then there's an issue. If not then there isn't. Plenty of rain is on the way, it's a good time to check.

If you seal it up then you'll stop more getting in but also stop it evaporating.

Has the driveway got higher over the years? Ideally it should be a couple of bricks below the DPC.

Also, the next time it rains heavily, get your brolly and see what the downpipes and drains are doing. Do you know where the drains go?

 

[Reno104]

Thanks will do this later. I do know that the soils under is wet through.

I’m not sure about the driveway, only been in the house 10 months, although I do know that just about everything to do with this house was done poorly. The drive is all cracked and raised at points and the drain company I got out for a different problem said whoever laid the drive has done some damage to a part of the drain. Surely the water should run down the drain (pictured) just not sure how to go about it. It’s coming up through to the fireplace and soaking through to the floor boards. I’ll add a picture for context.

 

[George_engineer]

You'll get a lot of the rainwater splashing off that hardstanding onto the wall.

It looks like the ground level has been raised when that patterned concrete was laid. Ideally you should dig down so the ground level is 150mm below the slate DPC and have ~200mm of gravel immediately adjacent to the house. A french drain would also help but the main culprit of splashback would be removed.

Check all gutters and downpipes are functioning and not leaking water onto the walls.

 

[lostinthelight]

Looks as if there may be a slate damp course below the row thats been injected that has now had the outside level built up, is there a lower area away from the house so you could dig a french drain at the foot of the wall to run into

 

[blup]

Your problem is that the dpc is only just above the ground floor level (slates) so the damp/rainwater is bridging it. Nothing to do with it going under the wall. Ideally you need a minimum of 150mm below the dpc, so reduce the height of slate chippings, and check if the fall of the drive takes water away from the wall not into it. Shingle is better than slate for drainage

Blup

 

[Reno104]

Thanks guys. The old slate dpc supposedly has failed that’s why another one has been done recently. I’m not sure when the drive was done like I said only had the house under a year and previous owner had passed away so obviously couldn’t ask these sorts of questions.

So ideally we need to get the drive re done so it slopes away from the house? When it rains the water just stands it doesn’t run away from the house if that makes sense. There is no lower level just the small drain in the picture at the front but obviously there’s no way for water to run down it as it’s just a tiny hole in the floor.

 

[Reno104]

Your problem is that the dpc is only just above the ground floor level (slates) so the damp/rainwater is bridging it. Nothing to do with it going under the wall. Ideally you need a minimum of 150mm below the dpc, so reduce the height of slate chippings, and check if the fall of the drive takes water away from the wall not into it. Shingle is better than slate for drainage

Blup

I assumed that the new dpc would still work as it’s higher off the ground? How does bridging work in this way? Sorry I’m not good with this stuff learning as I go!

 

[^woody^]

Problem appears to be splashing above the DPC.

Don't do any nonsense in the ground. Ground is always wet and foundations and walls below DPC will always be wet too.

Assuming the DPC is performing, and any cavity not bridged at DPC level ....

Change the defective bricks, then repoint any defective mortar. Then coat the wall to 600mm above ground level with a quality silane-siloxane based water repellent following the manufacturer's instructions.

Check the wall higher up too for defective pointing, or saturation from roof run off - ie check for water running in and down the wall.

 

[blup]

I assumed that the new dpc would still work as it’s higher off the ground? How does bridging work in this way? Sorry I’m not good with this stuff learning as I go!

If the new dpc is the course above, then the damp would be from water splashing above dpc level, or maybe dripping from gutter.

Blup

 

[Reno104]

Problem appears to be splashing above the DPC.

Don't do any nonsense in the ground. Ground is always wet and foundations and walls below DPC will always be wet too.

Assuming the DPC is performing, and any cavity not bridged at DPC level ....

Change the defective bricks, then repoint any defective mortar. Then coat the wall to 600mm above ground level with a quality silane-siloxane based water repellent following the manufacturer's instructions.

Check the wall higher up too for defective pointing, or saturation from roof run off - ie check for water running in and down the wall.

Can you explain what you mean by cavity not being bridged? How would this be rectified? Thanks

 

[foxhole]

Your brickwork badly needs repointing as it will speed rain penetration as it is.
Damp in fireplace will be from chimney, either not capped and ventilated and / or problems at roof level .You don’t have rising damp .

 

[stuart45]

Can you explain what you mean by cavity not being bridged? How would this be rectified? Thanks

Mortar and other debris in the cavity. The cavity might need cleaning out.
Edit, looking a bit closer, it could well be a solid 9 inch wall.

 

[lostinthelight]

.
Edit, looking a bit closer, it could well be a solid 9 inch wall.

I did wonder that going the number of visible bricks ends

 

[stuart45]

Looks like Flemish stretcher bond, which is normally used.on a solid wall.