Damp patch on wall

[Yukster]

My flat has damp patches a metre up from floor level. There is no damp visible underneath it or above it. There are problems with the roof -chimneys aren't capped, pointing needs redoing and some flashing was redone badly some years ago- where there's likely to be a leak and we're trying to get someone to fix it. But builders who's been to have a look keep saying that it might be rising damp. Having that fixed is expensive so I'd like to ask how can I find out if it's rising damp or not before spending the money to fix it? I can fix the roof and let it dry and see but I'm wondering if there is a way of knowing if it's rising or descending damp in advance?

 

[Yukster]

 

[JohnD]

how can I find out if it's rising damp

As a rule of thumb

it's not rising damp

As another rule of thumb

people who sell silicone injections will tell you that it is.

It's worth remembering that no injected chemical will repair a leaking pipe, a splashy shower, a broken drain, defective brickwork, condensation, overspilling gutters, or a faulty chimney. Or, in other words, it will not cure the most common causes of water in a house.

What is on the other side of the wall? An outside wall? A kitchen sink? A bath? A shed?

Why is there a towel hanging on the door?

What is the floor made of?

Is that lifted floorboards I see? Is there damp beneath?

Is there a waterpipe in or under the wall?

Is there a bathroom above?

Is the plaster under that peeling paint surprisingly new-looking?

Is there an airbrick or other ventilation in that chimneybreast?

Post some photos of the other side of the wall please. Include the ground beneath and the roof and gutters above.


Damp that starts a metre up a wall, in a straight line, is often damp that has been concealed by a waterproofing treatment; and as the fault that is the source of water has not been repaired, the water reappears above that treatment.

 

[Yukster]

As a rule of thumb

it's not rising damp

As another rule of thumb

people who sell silicone injections will tell you that it is.

It's worth remembering that no injected chemical will repair a leaking pipe, a splashy shower, a broken drain, defective brickwork, condensation, overspilling gutters, or a faulty chimney. Or, in other words, it will not cure the most common causes of water in a house.

What is on the other side of the wall? An outside wall? A kitchen sink? A bath? A shed?

This is a partition wall with the neighboring flat

Why is there a towel hanging on the door?

it's just there because i had nowhere better to put it at the time. This is a kitchen.

What is the floor made of?

it's a brick wall

Is that lifted floorboards I see? Is there damp beneath?

These are nicer floorboards brought in to replace the existing floorboards. I haven't lifted the floorboards so not sure

Is there a water pipe in or under the wall?

I will have to lift the boards to check

Is there a bathroom above?

Good question, It's the upstairs neighbour so will have to check

Is the plaster under that peeling paint surprisingly new-looking?

it is probably 5 years old

Is there an airbrick or other ventilation in that chimney breast?

I am not sure, I'll have to check, i don't live in this flat presently

Post some photos of the other side of the wall please. Include the ground beneath and the roof and gutters above.

That will be difficult but I can check with the next door landlord what is on the other side of that wall

Damp that starts a metre up a wall, in a straight line, is often damp that has been concealed by a waterproofing treatment; and as the fault that is the source of water has not been repaired, the water reappears above that treatment.

So is the likely source a leaky pipe in the wall or water coming from above, say from an uncapped chimney?

 

[JohnD]

If you lift the floor, you will see if if is wet underneath.

If not, it is not rising damp.

If yes, it is probably a pipe leak.

The chimneybreast is particularly wet, but the flank wall is also wet, which is not typical of a damp chimney.

Wet chimneys in old houses usually leave yellow or brown stains (and tar smell) from the tar and soot. Bedroom fireplaces that were never used may be clean.

As it is a kitchen it may be plumbing related.

If there is a bathroom on the other side of the wall, even more likely to be plumbing related.

The chimneybreast must be ventilated top and bottom. If there is no visible airbrick, drill into it just above the skirting. Look for wet rubble inside, and a current of air moving upwards.

 

[^woody^]

Who owns the freehold? That would normally be the landlord's responsibility.

I'd suspect a chimney problem or if an external wall a penetrating damp issue, before rising damp.

Do not allow anyone to inspect/diagnose if they will benefit from the work they will recommend. Get an independent survey first to diagnose the problem, then get other contractors to quote for the recommended work