Damp on outside wall

woodwormme

I’ve had a leak in the bedroom next to the chimney so the roofer suggested removing the stack. The previous owner of 2.5 years had one of the chimney stacks capped as well. Not sure when, but she did it. 

I’ve done that so that should remove the leak. However I’ve noticed that at the bottom of the chimney the wall is always damp looking (external). 

There aren’t any air bricks, which I will get done soon. The other chimney has an internal air vent plus a wood burner that I sometimes use. 

So what is causing the damp wall? Could it be the stack that was covered? Could it be the lack of air bricks (although there was still one stack that wasn’t covered). Or could it be pointing? Although I think the wall looks ok. 

With regards to the upstairs bedroom wall, that appears to be not so bad. Someone painted waterproof paint On the chimney, which stopped some water, but not all. 

Any advice will be fab. The inside of the chimney at ground level is fine. Perhaps it has stuff inside as it was bricked up at one point in time. 

woodwormme

Picture for reference 

FreeBear

A picture showing the roof line might help. But we can already see you have an issue with damp along the full length... The first three/four courses of brick appear to be pretty wet. Most likely from rain hitting the concrete and splashing up. The fix is simple though = Remove that strip of concrete between the wall & slabs. Dig down 200mm or so and back fill with gravel. Make sure that the gravel is at least one course of brick below any damp proof course, preferably two.

As for the damp higher up - If the chimney isn't capped, get it done. Insert a small vent at the base of the chimney, and monitor the situation. The pointing looks a bit rough, but it is functional and not really worth the expense of racking out and replacing (in my opinion).

murphydavid

I'm no expert but here's a few ideas 
Kind of hard to follow:
When you say capped do you mean sealed (air tight) or a cowl put over so moisture can escape but rain can't get in?
Are you talking about one chimney stack; with two chimneys inside it; with one going to a bricked up fire place upstairs and the other to a wood burner downstairs?
Is the internal air vent a component of the wood burner. ie where is the air venting from and to and what is driving it.
If the upstairs damp was next to the chimney it could have been the flashing round the stack at roof level - was it near the ceiling? did the roofer go up and investigate.
I would say the damp in the picture is not from a chimney that is capped and goes no further than an upstairs fire. Even if the division between the two chimneys had broken condensation from that one would not end up there. Regarding that chimney (not in use) I would remove the cap and put on a cowl if that is the situation and put in air bricks on the outside into the back of the bricked up fire place so it can decrease internal humidity and not damage interior decor.
To me the damp you can see is either a failure of the damp proof slates or membrane. A bypass of the damp proof membrane by materials added or maybe a concrete platform when the wood burner was installed or condensation. You say the previous owner had one chimney capped followed by "I’ve done that" so that makes 2. I presume that means there is a cowl on the wood burner chimney. Can you see if it is covered in tar and have you had it cleaned because wood burners require a special wood burner cowl and regular cleaning or it will get partially blocked.
I would look inside the stove for signs of water / humidity / rust. If that's inconclusive think of putting a cheap humidity meter in or under the stove towards the back (only when it is not in use) and if the reading is high try to increase the ventilation in that fire place. Check the air ventilator is functioning. Maybe a simple thing like leaving the stove door and damper open to see if things improved. If its condensation the damp won't be noticeably different for a long time but the humidity meter should tell you if you are on the right track.

woodwormme

@FreeBear yikes ok! There is a house just next door that is protecting most of the wall from rain. Is this damp an issue  

I’ve had the chimney removed @murphydavid I don’t think my post was clear. I’ll read fully and reply. 

woodwormme

Hi I’m sorry my posts don’t make sense. I do have a habit of jumping conversations, I have a hard time expressing myself I will number if it makes it easier. 

1) I have the typical two chimneys in a Victorian semi detached house. Living room and dining room have chimneys. Living room is at the front of the house. The picture was taken from the garden. Therefore the problem damp is at the dining room. 

2) the living room chimney had a wood burner installed up to 2 years ago. That chimney has internals issues, but I don’t complicate the conversation. 

3) My chimneys have two stacks. The problem dining room chimney has one stack that was capped, the other had a cowl. This chimney hasn’t been in use for many years. The previous owner capped the chimney and had repointing done (so she says). Neither removed the damp internal wall. 

4) Various roofers suggested removing the chimney as the pointing was a bit rubbish and it was made from different bricks. I removed the chimney stack from the dining room this week. However he didn’t put in air bricks for this chimney. Is that a problem? 

5) the side of the house is mostly protected from rain due to my next door neighbour. So yes the DPC must be failing.

6) I shall 100% remove the concrete from the side of the house. Will this improve the damp? 

7) damp is fine within the house. Damp readings are within normal range and also I don’t have an issue with condensation etc. 

woodwormme

@murphydavid

1) hi yes the roofer went up on the roof and the loft. 

2) the wood burner had the correct stack. Next door have the same stack and they have a burner. That chimney with the wood burner isn’t the issue at the moment. 

murphydavid

Ok so at point 3 you say "Neither removed the damp internal wall". So is the damp we can see on the outside also have a damp wall on the inside?
If you can see the damp proof line (horizontal line of mortar a bit thicker than the others) which I think I can about 2 and a half bricks up and there is no damp inside I would not do anything to the path till I checked if removing the dining room chimney breast (removed the chimney stack from the dining room this week) has solved the issue. You won't notice a rapid change it takes time.
I presume the inside wall where the chimney breast was is now bare brick work.
So more questions. From the outside brick pattern it appears that the wall is a cavity wall.
Is there it a cavity wall where the chimney breast was or is that now single thickness.
Is the wall at that point damp or dry inside? 
To answer one of your questions directly. Although you might not get a problem the correct procedure for the remaining piece of the dining room chimney is it should have had a vent installed when it was capped and it should now have a further vent installed at the bottom. You should also check the proportions of how much stack is inside the building and how much is outside.

Also this may be of interest
https://www.practicaldiy.com/general-building/chimney/chimney-breast-removal.php

Doozergirl

Have you checked in the loft to see if there's any evidence at all of a leak from the roof?  If it's visible outside then I'd say its getting a soaking somewhere and more than just a ventilation issue.  

I'm in absolute with freebear.  You need to remove that concrete from the side passage.  Someone did it properly initially and laid the paving away from the wall and then someone else has come along and put that concrete in. 

The damp proof course is being breached, it isn't 'failing'.   I don't think that is the only issue though. 

murphydavid

Doozergirl said:

I'm in absolute with freebear.  You need to remove that concrete from the side passage.  Someone did it properly initially and laid the paving away from the wall and then someone else has come along and put that concrete in.  

IMO If the path is below the damp proof membrane in the wall I would not mess with the path. Block paving is held in place by the perimeter and will come loose without it so if the concrete is removed a new perimeter will be required to stop the path breaking up. If the concrete was not put in when the path was laid the blocks would not have remained in place. If done properly its on a sand base and the sand must be captivated. There appears to be a gap between the concrete path perimeter and the wall so it was done like that so as not to use the house wall as the perimeter.
If there is a problem with rain splash up it is normally resolved by impregnating (paint on or spray) the splashed area with a silicone damp proofer and if the membrane is damaged removing the concrete will not help and might even do more damage to it. If you do remove the concrete and it is against the wall remove some of the paving first as smashing the concrete while it is captive to the wall could put pressure on the bricks in the wall. 
Something like this will protect from rain splash although a solvent one might be better outside.
https://www.amazon.co.uk/Everbuild-WAT5-Water-Seal-402/dp/B0012LETNK/ref=sr_1_10?keywords=silicone+wall+sealant&qid=1584442256&sr=8-10

Doozergirl

That is an old house.  It shouldn't have a damp proof membrane and those are paving slabs, not block paving.  If there is a problem with the concrete breaching the original damp proof course then it will solve a long and ongoing problem.  The paving isn't the 'keeper' here, the house is the asset and no one should be laying concrete against the side of a house like that.  Any perimeter can and should be laid away from the house.  

You should never put any type of damp seal on an older building, lime mortar is designed to pull moisture out from inside the house.  They breathe.  It's modern methods that stop a house from breathing that start to cause and compound issues.  If the mortar is replaced with a cements mix, then the brick become the softest medium and they start to do the job that the mortar was designed to do.

There is evidence of a previously injected damp proof course, which, of course, isn't working, because they don't work.   

Where I have seen this before, it was a roofing problem.  The back gutters had split and there was water pouring down the walls, but it was only showing at ground floor level where it was spreading out.  

I was going to say that it would be useful to see the walls inside, but there's probably waterproof render on them hiding it.

OP, where is the inside floor level and what type of floor is?  Solid or suspended?

It might also be an idea to check how the wall looks and the ground around it when it's actually raining.