DPC Sleeper wall, rising damp?

[nero44]

Hello,

I am in the process of cleaning up my victorian cellar, which is progressing well. Currently fitting/replacing some of the insulation between the joist and I have encountered a damp spot.

I would like to know what your guess is for the source of this and if there is a cost effective method to remediate this to avoid further damage. Let me paint a picture for you guys:

This is under the floor at the rear side of my house. There is a balcony door leading out to the side return. There is also my SVP in the corner connecting to the sewer. There is no smell, so I doubt it's a leak of the SVP or the sewer below. The SVP has recently been refitted. The suspended timber floor sits on joists, which sit on a wall plate, which sits on these "sleeper walls". I don't actually know if this is still considered a sleeper wall if attached to the outside wall of the house. On the above-floor-image you can see some evidence of damp coming up on the wall to the right of the balcony door, but I think it's an older mark. I scribed a line around the patch 6 months ago and it hasn't moved since.


The damp area is where the copper pipe goes up to feed the radiator above. Also here the copper pipe feels dry, so I don't think that is leaking. With the amount of damp I would be loosing a bar a day on my closed system if it were that. The soil in the area feels damp to the touch (nothing too surprising for this type of property), so are the bricks of sleeper wall and you can see how it penetrated the wall plate. The two sleeper walls before appear dry, however the wall they are attached to is still internal. Other info, it has not rained in days at the time of the picture.



Here are my thoughts: the outside ground closest to this is dry (as it hasn't rained in a few days), so I don't think there is water ingress from the outside going through the wall plate and through the sleeper wall into the ground. My guess is, the soil is just damp (as commonly is) and penetrates up the bricks, and since there is no DPC between the sleeper wall and the wooden wall plate it penetrates the timber. The joist that sits on the damp wall plate appears dry, but I think I see some historic water stains, so it may have been impacted previously when dampness was high.

What can I do here safely to have some sort of DPC, to stop damp going up into the wall plate?
- Get a Damp Proofing kit, drilling a few holes and injecting a chemical DPC?
- Could I source a thin metal sheet (like a stainless steel sheet) and dry and hammer it in the mortar to form a barrier?
- Any other ideas/suggestions?

At some point I am looking to get a side return extension done, so the area would be dug out, but who knows when that will be.

Interestingly, the sleeper wall before is not even fully supporting the wall plate. I am thinking, in this gap I could simply push something in to create a barrier? Or rake out and apply new mortar? Although that might then just create the bridge to let water into the wall plate above...


Thoughts?

 

[nero44]

Alright, so this is would be my gameplan:

1. Tackle the sleeper wall that is dry, but not fully resting on the timber

- slightly prop up the wall plate by putting in some short timbers left and right of it
- completely rake out old mortar
- add a new thin layer of mortar on brickcourse, slide in a bit of DPC roll, and then fill in the rest up to the timber wall plate
- let it completely cure so it has proper support and actually resting on the sleeper wall

2. Use dry rods on the damp one

- clean our all the debris that is on the wall plate, it might be bridging moisture from top/behind
- leave mortar untouched, drill holes under first course of bricks (counted from above) at indicated locations, potentially all the way through single course and into the main wall behind it
- potentially also drill holes left and right directly next to the sleeper wall
- insert dry rod sticks, close with fresh mortar
- hopefully the chemical can then form a dpc inside the old mortar. Doesn't have to be perfect but any improvement will probably help to keep the timbers above dry(er)

Insulate between joist as planned.

Any thoughts on above pls? Never worked with this dryrods, but seems easy enough.

 

[nero44]

Ok, so done on 1. Was pretty straight forward.

For 2. the mortar was quite crumbly. I did end up putting a few dry rods in there where I could, but only a few cm into the mortar. So the effect will be minimal if any.

I managed get my arm around the sleeper wall and noticed that moist soil was backed up all the way... So managed to push all the soil away, at least 2 brick courses down. I suspect this was the main culprit... backed up soil behind the wall bridging damp all the way up into the wall plate. I think this should now be much better.

Lesson of the day, look for / remediate the actual source of damp before using DPC injections etc...

 

[nero44]

Alrighty, so turns out it was not the main culprit as that wall plate is still pretty damp... I've lifted some of the decking on the outside to assess the situation there.



there was a lot of debris in the area, so wondering if that prevented water from running down the slope naturally to the next gully. The DPC is actually very low here, as it's the highest part leading up to the house. It's basically on floor level under that last course of bricks. On the right side (where I see the damp from the inside void), there seems to have been some mortar/render which has broken off. I am aware that ideally there should be none as it could bridge the DPC, but also somewhere under there in the corner, there is a hole. I could stick a screw driver in there.

As a temporary fix to avoid any rainwater potentially running down that hole, would it make sense to slap some waterproof cement there to fill that render/corner back out? I will need to get rid of the entire dreadful decking at some point anyway, but for now I am looking for something to minimise the chance of more water getting inside.

 

[noseall]

Alrighty, so turns out it was not the main culprit as that wall plate is still pretty damp... I've lifted some of the decking on the outside to assess the situation there.

View attachment 399388View attachment 399389

there was a lot of debris in the area, so wondering if that prevented water from running down the slope naturally to the next gully. The DPC is actually very low here, as it's the highest part leading up to the house. It's basically on floor level under that last course of bricks. On the right side (where I see the damp from the inside void), there seems to have been some mortar/render which has broken off. I am aware that ideally there should be none as it could bridge the DPC, but also somewhere under there in the corner, there is a hole. I could stick a screw driver in there.

As a temporary fix to avoid any rainwater potentially running down that hole, would it make sense to slap some waterproof cement there to fill that render/corner back out? I will need to get rid of the entire dreadful decking at some point anyway, but for now I am looking for something to minimise the chance of more water getting inside.

Can you compress your post into a simple question? Folk are going to lose interest.

 

[nero44]

Can you compress your post into a simple question? Folk are going to lose interest.

Morning, I think they already have given the lack of activity on this. I am basically just writing this as my own DIY journal for myself

Jokes aside, somewhere in that corner there is a hole which might allow moisture to run into my cellar. This section of the house is going to be rebuilt at some point, so looking for a temp fix. blue line is current DPC.

Question, would/could it help to refill the green area with some waterproof repair cement or is that going to make things considerable worse given that I might be creating a bridge...

 

[foxhole]

Looks like penetrating damp caused by rain hitting decking ( which is too high) and splashing walls above the dpc, exasperated by rain run down soil pipe . Have you checked gutters above?

 

[nero44]

Thanks for responding. Gutters above are clear. When it rains, that corner with the SVP is actually not terribly wet. However penetrating damp was definitely an issue. The deckboards were touching the walls! I have gone in with a jigsaw and took an inch off (with a long term view of removing this decking all together). Also the ground has had a chance to dry now that I removed some of that soil and debris. I might lift a few more boards to make sure water has a path to run down the side return to the next gully.