Rising damp?

[bullethead123]

Hi all,
I have 2 damp patches in a downstairs party wall which get noticeably worse when it rains. The neighbours have no damp at all on their side of the party wall. I have started a similar thread on the Roofing section as I did have some work done on the roof last year for a patch of damp upstairs but I have been told the source of the problem is unlikely to be the roof, given that the damp only appears downstairs.
As can be seen from the pictures below, the damp patches start approx 1M up from floor level and are separated by the width of (what used to be) the chimney breast. Someone mentioned to me that it might be 'rising damp'. Would this be a possibility given that the dampness is much worse when it rains?
One other contributory factor could be that there is a leak in the pressurised hot water system. I know this because I have to recharge the system from time to time.

Read more: https://www.diynot.com/diy/threads/damp-wall-could-it-be-a-leak-in-the-roof.554546/#ixzz6aHmpZku1

 

[dontbelieveawordofit]

rising damp , most likely
central heating , highly unlikely.
just my opinion.

 

[JohnD]

the wet patch appears to start a few feet above the floor. Is it a concrete floor?

I doubt that "rising damp" can leapfrog up a few feet.

So maybe some kind of damp-hiding treatment has been applied to the lower part of the wall (a metre is typical) which obviously has not stopped the damp, just hidden it

or there is a source, such as a kitchen sink, bath, pipe or gas-fire.

What do you think is on the other side of the wall where the wet patch is?

Have you got a water meter?

Stand back and photograph the whole wall, floor to ceiling please. move the furniture and picture out of the way.

Pull back the carpet. is the floor wet?

 

[bullethead123]

Hi, and thanks for the input.
The floor is wooden floorboards.
There is a radiator on an adjacent wall in the same room but the pipes don't go near the damp wall, they are about 3 feet away from it.
The mains water comes through this room, but that pipe is about 7 feet away from the wall.
I have removed some floorboards to check these pipe connections for leaks due to a problem with the C/H (I have to periodically charge the system as it keeps losing water) but found nothing amiss.
Though the ground underneath the floorboards felt cold, I wouldn't say it was damp.
There are 2 other rads downstairs, one in a separate room and another in the same room but about 20 feet away from the damp wall.
Having spoken to the neighbour, they have no evidence of any damp on their side of the same wall.
I do have a water meter.

 

[bullethead123]

Hi again, just resurrecting this thread with some new info.
I have inspected the pipework to the kitchen rad and all joints seem watertight.
I then lifted up a board near tha damp wall and found it quite damp:

Also, there was damp sandy debris piled up in the sub-floor corner, so much so that one of the joists seems rotted (top right of pic above).
Some slate material was also found. I guess this is something to do with the damp course but perhaps it is from the pier that supports the french doors on an adjacent wall, part of which is missing:

There is an airbrick in the adjacent wall, in the corner of that wall and the one sffering from damp but it goes nowhere. Its height is at a level with the skirting board and it is totally obstructed by plaster and skirting. Seems kinda odd.

Anyone got any ideas?

 

[JohnD]

Stand back and photograph the whole wall, floor to ceiling please. move the furniture and picture out of the way.

Pull back the carpet. is the floor wet?

please include something in your photos to show scale.

 

[JohnD]

looking at your photo 11 Oct the damp patch seems to be about a metre up the wall, so either there is a damp-concealing render below it, or there is a source such as a pipe in the wall or a sink on the other side.

The pic is not floor to ceiling.

The right-hand-side of the wall is either wet or shaded. Can't tell which.

 

[tel765]

You've got rising damp and possibly chemical damp from an old flue - there's also severe rot on the joist.
Given the party wall was the back wall of a chimney breast flue - if the soot was not cleaned off you will get chemically caused damp on the decorated surface - when it rains the humidity will attract the "damp signs".
Does the neighbour have a chimney breast backing on to that position?



You need to lift one or two boards next to the one you've already lifted - & post pics of the construction detail, and other joist tails down there.
I dont know for sure but the bit of plastic showing could be the bottom edge of an attempt at tanking with a plastic sheet - moisture goes up behind the tanking sheet and appears higher up? edit: i assumed at the time you were talking about and showing only the party wall.

Can you post pics showing the outside of the external wall at ground level?
And external pics of the door & its threshold?

This thread probably belongs in the Building Forum.

 

[bullethead123]

You're right John, the damp patch starts about 1m from the floor. The small patch on the right hand side of the picture is also damp and seems to be just to the right of where I would imagine the old (removed) chimney breast was.
It is a party wall and the folks next door have a large cupboard up against their side of the wall. They have moved it and say there is no damp on their side.

You don't think the source of the damp could be ground saturation caused by rainwarer seeping in from outside? It certainly seems worse when it rains.

 

[bullethead123]

Thanks for your input Tel. I'll take the pics tomorrow and post.

 

[bullethead123]

Hi Tel,
First of all, the damp is not in the line of where the chimney breast would have been, rather it is to either side with the side nearest the corner by far the worst. The neighbour tells me that their chimney breast is still in place with a vent at the bottom.

Here are the pics you asked for:

Overview.

Joist nearest corner.

Next joist along.

And the next.

Between joists 1 & 2.

Between joists 2 & 3.

The two pictures above are included because they hopefully show the missing brickwork which shoud be holding up the french door threshold. Perhaps this is where all the sandy debris (referred to earlier) that was piled up at the corner joist came from?

Evidence of a previous damp course?

Sub floor wall.

Adjacent outside wall.

Note: the airbrick shown is above sub-floor level. It is, in fact, at the level of the skirting board and just above and is totally obscured.


Door and threshold.

Come to think of it, around 5 years ago I dismantled a plastic roof which covered the area outside the french doors to a distance of 8ft. I have had the house 10 years and only had the damp problem the last two.

Not wanting to jump the gun, but do you think that the water that is causing the damp may be coming in from this area?

 

[tel765]

Thanks for the pics and info.

The damp penetration is long standing.
There has been previous Damp & Timber work - injection holes can be seen inside the sub- floor and on the outside wall.
The timberwork - joists, floorboards & skirting - is not original.
Square edge floorboards are typical of cheapskate D&T Companies.
DPC material is necessary to isolate all timber work it wasn't provided.
Through ventilation from rear elevation to front elevation is req'd under suspended floors.

The exterior:
The pointing needs raking out to 20mm depth and repointed with a 4:1 sand and lime mix.
I assume this is a solid wall?
The ground level needs dropping.
The concrete sill needs dropping. The elevation needs vents or air bricks esp under the sill.
Remove the present air brick and gash mortar and make good to brickwork.
There is an abutting yard wall - possibly causing penetrating damp?
The coloured silicone sealing around the door frame should be cleaned out and renewed - it might be best given the condition of the wood sill, and frame bottom rail, to temporarily remove the door for remedial work.
The conc sill seems to be allowing pooling.

 

[tel765]

I'll be back later to discuss the interior.

 

[tel765]

The Interior:
Moisture is penetrating through the incorrectly installed wood sill - and the threshold below the sill.
No sub-floor ventilation can be seen. Damp moist conditions lacking through ventilation are ideal conditions for condensation and wood rot.
All woodwork below the door is rotting. The plastic is an attempt to form a DPC but its actually introducing moisture into the sub area.
There's no sign of a mechanical DPC in the jumbled masonry - S&C mortar has been daubed on the sub area walls in maybe a strange attempt to prevent penetrating moisture?
The plate the joists sit on, the joist tails and floor boards are rotting - suspicious, possibly dry rot fibres and fungus can be seen.
Examining the back of the skirting would show any further rot.
Its possible that fungal fibres have moved up behind the plaster.
If it is Dry Rot my method would be to remove all damaged or even discoloured woodwork, and replace with treated and DPC protected new materials.

 

[tel765]

Ref: The damp signs on the party wall and the interior wall.
The info and pics so far is confusing.
More pics and info ref these areas and exactly whats happening with your neighbour would help?
So would a pic showing more of the yard wall and the whole of the elevation to eaves?