No render against drainage and no DPC on garage wall

[tinoater]

Occasional DIY bodger here, haven't done external work before.

The problem is damp on the floor in the garage which was built as a recent extension before I bought the house. There's a drainage channel on the outside of the wall that isn't rendered and I think the water's coming in there. Usually this channel is filled small decorative stones which I've cleared away. I can't see if there is a DPC for the garage... I think I can see the DPC line for the house but not the garage. There are some random red plugs in the wall below the render, could it be they injected some DPC cream in there?

Not sure what's best to do so any pointers would be helpful! Everywhere says not to render below the DPC but I don't know if there is one and in any case it looks like that strip needs some waterproofing on it? If I do need to render that strip then I'd like to do it myself as it'd be a tiny job for a plasterer.

TIA

 

[Mike13]

the damp droof course is above the finish to the render, so that bit with the two hand painted arrows on it is bridging and allowing the damp to flow back up and into the wall inside I think. the render should really finish at the line of the dpc pointed out in picture 2 I also think, but that would involve using a cutting wheel to trim back the render a little, then making good on the wall?

 

[tinoater]

Thanks for the reply.

On picture 3 I don't think there's a dpc on that wall - at least I can't see one. It looks like a single layer breezeblock wall and looking between the blocks on picture 4 I can't see any dpc. The dpc line on picture 2 is between the bricks on the house, the garage wall was built separately. The damp looks like it's coming through from that area, so I'm guessing it's the problem.

If there is no dpc on the garage wall then would rendering down to the bottom help, or potentially just do nothing as the water could just travel up it and through the breezeblocks into the garage still?

 

[Mike13]

cant tell on the rest from photos given, but the render to the left of drawn arrow in pic 2 is potentiall bridging the dpc on that wall. you need some more careful investigation to find out what is there on the rest, any of us could not be certain about what is there from current pics.

 

[tinoater]

Ah I see what you mean about the render to the left of the drawn arrow in pic 2, but actually that wall isn't a problem, it's the wall to the right of the upvc door that's the issue.

A close-up of the problematic breezeblock wall is below. Should I be able to see some dpc between the blocks if it was there? It doesn't look like it to me. The only thing I can see is some black sheeting that looks like it's under the concrete floor (second pic), is that some sort of waterproofing, or just what you have to lay down before you concrete a floor over it? Note the line of DPC on the course above it, that's the continuation of the dpc line from the 2nd pic that's on the bricks of the house, not the garage.