Rising damp or condensation?

[whatnumber]

The internal plaster has been flaking off a large area of our north facing living for some time now.
This is an extension built before us - maybe 10-20 years old.
The damp is also appearing low down on what would have been the old outside wall but is now the wall edge of an internal fireplace (third pic).
Before winter we did insert those silicon injections ourselves incase it was rising damp. Have also re done any holes in the pointing again as there were quite a few. There was a large hole behind the tv wall (2nd pic) half way up which is now filled in.
I have resealed the French drains as the joints were letting water through to the ground. I have also sealed all the walls outside with breathable wall paint seal.
Is this enough?
Had two plastered around to quote on re plastering . I have asked for breathable plaster. They wasn't sure what would have been causing the damp and we're worried the new plaster would just come off again.
There is no ventilation in the living room and we do get a lot of condensation. Could it be internal condensation reacting with bad plastering and metal beading etc?
I'm not sure where to go from here.
@pigletjohn I know you are an expert if you or anyone else could offer some ideas of what we could do next thank you.

Not sure why the house is on its side!
Yes the wet wall is the extension and the dry wall is the original house. All three of the new extension walls are the only ones effected. All have the white appearance above the dpc. Does that mean the dpc has failed on the extension? Is that the silicone injections to fix it?
the gulley it drains into looks is in the gutter on the floor of this wall. I guess it goes into the garden underneath the patio. There is water in it. I’ll post a picture. This is also the pic of close up dpc. The dpc is two bricks up

Down the side alley the paving slabs have been put on top of concrete. But around the rest (and most) of the extension they are on a bed of stones then sand it seems.
At the back of the side alley there is a manhole cover for the toilet waste I think but I'm sure it goes the opposite way under the house so wouldn't go anywhere near the extension.

You could run a hose onto the paving stones and see which way the paving slopes and if water runs to gutter. And if it then runs away freely.
We have such heavy rain nowadays perhaps the gutter is overwhelmed.

well that's interesting

the efflorescence is well above the dpc.

if water is coming from below the dpc should stop it

I wonder if water is getting into the cavity from the windowframe of the roof over the extension

can you drill a 6mm hole in the mortar just above the dpc, at the wettest looking part, and see if water ever trickles out?

measure down from the windowsill inside then out and chalk on the outside wall where the internal floor level is, please

is the damp related to periods of heavy rain?

put a hose in the gutter and see if the water runs freely down that pipe hole

I can't actually see the dpc. Is it a black line? can you do a close-up pic please? put your finger on it.

ta

I’ve run the hose into the top gutters. They seem to be working well. The floor gutter is working fine too. Draining away a lot of water down the hole in the previous picture.
I’ve run the hose on the patio slabs. The slabs aren’t angled towards the house but the water is draining away quite quickly into the dirt between the slabs in front of the floor gutter. Is this my problem - do these need to be filled with concrete to create a barrier so the water sits on top rather than soaking into the ground? We do get a lot of weeds and grass between them in the summer.

Yes the white effervescent is below and above the dpc on all three new walls. Only the new extension, not the old.
The roof looks in good condition. Would it be leaking on all three walls and not show signs higher up - internally or externally?
also the window seals look fine - would it be showing signs on all walls if large window on one wall only?
The dpc is the black line.
The internal floors are level exactly with the dpc.
Its seems much damper in the winter thus rainy season, yes.

Yeah that is fine OP. If you see below that is how your house would typically be constructed. The floor slab in line with DPC. And you have that aco channel in front of the outer wall. It is looking still like a damaged aco channel to me. Some water could still be flowing through. Efflorescence can just come from the bricks themselves rather than hard tap water although yes a leaking water main is possible if it is running just alongside that wall. It could possibly be a poor underside of cill but the amount of water looks more like rising damp to me.

Thanks for diagram.
I did repair the aco channel which was leaking in the joints.
How would I know if that is enough?
This extension is at the back of the house in the garden - I just don't see how any water pipes would be anywhere near it.
I keep reading rising damp isn't real and the dpc should be working to protect the above bricks even if the aco channel is Damaged?
Do you think the patio should be sealed between the slabs in front of the aco channel as water is soaking into the floor there when I put the hose pipe on it

I’m more wondering if you are getting water leaking into the cavity between the 2 leaves from the drain.

Piglet John would know better but where I am we build the wall below ground a bit differently to that drawing I put up there, we often put a block lying on its side below ground but in the diagram I put up for you the 2 block walls are built straight off the foundation filled with concrete below ground. I’m wondering if water might be seeping in there into the cavity there from the drain and that would explain why it is coming up above the dpc. But obviously I’m not sure.

We potentially have Rockwall cavity insulation in the cavity -
I got a certificate for it for the house when we purchased.
Would that soak up the water above the Dpc?
When you say the drain do you mean the aco channel or the circular drain where the water from the aco Chanel drains away?

I meant the hole that (ought to) lead to a drain.

Cavity fill is not absorbent like cotton wool, so will not wick water upwards. The DPC should prevent water rising g up the wall from below.

If, however, water is getting into the cavity from above, cavity fill may slow it drying out.

If you can drill a hole into one of the vertical mortar joints just above the DPC, it will be interesting to see if water dribbles out, especially after rain.

Thank you I will drill a hole and wait for rain!
There were many holes in the pointing which we have already filled in.
Do you think that would have let enough water in to cause all of this damage?

Running with the theme of water coming in from the top I’ve got on the ladders and can see there are cracks in the mortar in between the bricks above the window - would that let enough water in?

Also cracks between the new extension and old wall.
I can see someone has tried to repair the to wall side where the edge of the roof is too.

i can't see the holes in the brickwork you mention. Might be because I can't enlarge the pic.

the flashing looks like it has had a silkicone product added to seal it into the wall, which is not usually correct but silicone products are noe available, as the old lead-roll and mortar method used to fall out.

the bay roof appears to be lead, and if properly done should be OK. squirt some water on it and see where it runs to. Lead roof repair is a specialist job now. Nothing stands out as being wrong, as long as the water runs out, and not towards the house.

its rather common to have water penetrating round a window frame if badly fitted. Morar filetrs tend to fall out. Plastic trim is often glued over gaps to hide them. Plastic frames have internal drainage channels, and weep holes at the bottom so water can escape without getting into the wall. Look at the joint between frame and brickwork, and underneath the frame. There should be an exposed drip groove to prevent water tracking inwards. I think all your wet marks are at or below the height of the windowsill.

"Also cracks between the new extension and old wall.
I can see someone has tried to repair the to wall side where the edge of the roof is too."

(doesn't seem to be a "quote" command in this version of Mumsnet)

it looks like the new brickwork has not been toothed into the old, which would be a better quality job.

I can't make out the repair you mention. Can you do a close up of the repair, then stand back and show the context where it is on the wall. Upright if you can.

It looks like concrete has been used to seal the led flashing to the wall. Is that a bad thing? It looks in good condition.
I’ve had a good look at my windows and poured lots of water on the bay window lead roof.
The side seals for the window seem fitted and siliconed in well.
The led bay window roof seems fine, all the water falls off it onto the window seals.
The window seals do have the lip beneath but so much water still falls onto the wall above the dpc so they are now soaked. The window seals only come out 1 3/4 inches above the bricks. Isthis enough?

In theory it seems to make sense the problem is from the two windows and they have been badly fitted as on the corner not underneath a window there is no effervescence. But then this doesn’t explain the tv wall effervescence which has no window. Would the large hole in the outside mortar on the tv wall explain that effervescence? (We have now filled this hole in).

Lead flashing is inserted into a slot cut horizontally into the mortar joint of the brickwork above the window, then dressed vertically down the wall, then dressed horizontally over the lead roofing, which itself should be turned up where it meets the wall so that water cannot get behind the lead and wet the wall. It is (was) wedged into the slot to delay it falling out, with rolls of scrap lead, hammered in, and thern the slot filled with mortar. That traditional method has been superseded by grey silicone injected into the gap, it's sticky and flexible so doesn't fall out like old mortar. Either is OK if in good condition.

I don't think I can see a gutter round your bay window roof. Where does the water go?

I think you describe the water draining onto the wall and running down it. This would certainly make it wet. But it shouldn't get into the cavity unless it finds a gap, for example round or under the window. There might be a gap under the windowsill. Can you take some pics from below and the side please.

In the event that the source of water is rain running off the bay roof, it could easily be solved with a small gutter and a downpipe running to your Aco channel.

I will look for a pic showing how the drip groove in a sill should work.

here we are

door sills and window sills both have this

imagine rain blowing against the face of the door or window and running down

it runs onto the sill, then runs down the slope and the edge.

it will tend to cling to the sill and run round the edge to the underside. But it reaches the groove and, not wanting to run uphill, drips off.

If the groove is filled by dirt, paint or filler, or of the sill does not project far enough from the wall, water will run round and wet the brickwork

the one in the pic is a drawing of a concrete or wooden sill, but plastic windows have something similar.

and this is a good vid showing how the sill is fitted. I'd expect it to project about 100mm beyond the face of the wall, but I just saw 5 inches (125mm) mentioned. The window supplier would have instructions according to their design. Down my road we have sloping brick sills so I can't measure one to check. Except my neighbour has stone sills with about a foot projection on corbelled brackets, so quite different.

Yes all the water from the bay window runs down the window. Maybe a gutter would be a big improvement.
Here is a picture underneath the window seal.
It definitely has a groove. However the window seal only protrudes 4cm away from the bricks underneath.

This edge looks like it could need new silicone?