Damp Proof Course Type

[Stevecc]

Hello

Can anybody identify what type of damp proof course this would be. It just looks like a thicker layer of mortar from the outside.

 

[Bonni]

DPC can be slate, bitumen, plastic, and in the rare instance copper.

 

[Stevecc]

Thanks for your reply. Not sure what my DPC is made of, there is a thicker layer of mortar between the wet bricks and dry bricks

 

[tell80]

OP,
Whatever is going on, mechanical DPC or bed of mortar, its doing a great job.
If you scrape away a little of the mortar it should reveal any mechanical DPC inserted in or below the mortar.
Is your question just curiosity or do you have damp issues inside the property?

 

[Stevecc]

Yes it does appear to be doing a good job. I guess there must be a DPC under the mortar. I think I'll do what you suggest and take a little mortar away and see whats underneath

There is something going on the in property. At the extension the plaster is discoloured and paint peeling

 

[tell80]

Did you find a DPC?
Why not post pics of any discolorisation or bubbling paint/plaster - close up and context shots will help.

 

[^woody^]

The thick mortar is a DPC joint, not a DPC.

This joint consists of
mortar
the DPC material (bitumen felt in this case)
mortar

There is no need to scrape away anything, you can see that there is DPC there as the wall below is damp and the wall above is dry.

 

[Stevecc]

tell80 i'll post some photos soon, basically walls look stained and paint peeling

woody you think its a bitumen felt DPC. What makes you say that, I can't see a bitumen felt membrane sticking out

 

[tell80]

Stevecc,
Scrape at the mortar bed if you want you wont do any harm. Maybe you will find, as I mentioned, a DPC inserted in the mortar.

Bonni also mentioned "bitumen" if thats what the DPC material turns out to be.

Certain mortar beds sometimes act as the "DPC" & enable the wall above the bed to remain dry.

 

[tell80]

Just noticed your last post:
Have you already tried scraping it out a little?

 

[Stevecc]

I'll scrap some of the mortar and see what I can find.

There is nothing sticking out of the mortar, such as a mebrane or slate or bitumen, along its length

 

[Stevecc]

Update

It turns out the DPC was slate buried in the mortar. Also I think the slate DPC spans the cavity

 

[JohnD]

it's been repointed over. The moss and stains show there is a great deal of water there. Please stand back and take a wider pic. You need to find the source. It may well be a broken drain or pipe leak. Show all pipes, manholecovers, drains, and also the gutter and downpipes.

the white marks are often found near a washing machine, from the soapy water.

 

[Stevecc]

Thanks I'll take a wide photo.

I think it could be the wide gap between the wall and the concrete pathway that is allowing rainwater into the foundations and wetting the wall and causing the algae to grow.

Not seen the roof leaking. Not sure how to detect a leaking drain

 

[JohnD]

downpipes and kitchen sinks often go into a gulley beside the house. Older houses have glazed clay gullies which IME are always cracked or broken and leaking. I'm told there is an unbroken one somewhere but I have never seen it.