mould / damp

[low drains drifter]

Hi everyone, does anyone have a checklist when trying to work out where mould / damp is coming from? This concerns the inside of an external wall with cavity construction.

 

[Wayners]

Watched skillbulder on youtube that covered subject?

 

[JohnD]

You don't drape wet washing indoors, do you?

 

[tell80]

OP,
why not post pics of the problem showing the interior, and the exterior elevation & at ground level?
Is the floor solid?
Do you have CWI?
Is the outside rendered?
Any previous damp work?

 

[low drains drifter]

You don't drape wet washing indoors, do you?

this is a rental property. the mould is in the stairwell, so there is no room to put clothes there. But yes, this can be a problem where the property is "sealed" with double glazing and is heated with a gas boiler.

 

[low drains drifter]

Watched skillbulder on youtube that covered subject?

thanks, I watched the video on coating the walls. I was hoping that coating the walls (possibly roughcasting) would be a last resort. Not sure about a price but I'm sure it would run into the £0,000's. I'm tempted to start with getting the gutters and downpipes flushed out. This can be done quite easily and not too much £'s

 

[low drains drifter]

OP,
why not post pics of the problem showing the interior, and the exterior elevation & at ground level?
Is the floor solid?
Do you have CWI?
Is the outside rendered?
Any previous damp work?

why not post pics of the problem showing the interior, and the exterior elevation & at ground level?
yes, would make sense. I don't live at the property and I was trying to have a sniff around to see what order I should do things in. I was going to go, gutters and downpipes, ventilation vent in front door, air brick and if all that fails then consider doing something to the outside wall. Are there any steps that I have missed out? Can I try anything else?

Is the floor solid?
this is damp at the top of a stairway.

Do you have CWI?
this is a first floor, 4 in a block flat. cavity walls, yes; cavity walls insulation no. I've been told that the cavity wall insulation is not suitable in this type of property. Not an expert, but I was told that cavity wall insulation could bridge the gap between outside and internal wall.

Is the outside rendered?
no, but a lot of these buildings have been roughcast. can't imagine much change from £5,000 for roughcasting.

Any previous damp work?
no, no previous damp work.

 

[^woody^]

Structural damp is always evident, and the cause very near to the stain.

Likewise for leaking pipes.

In the absence of structural damp or leaks, black mould is always from excess humidity created by the occupants. Always.

 

[tell80]

Without seeing pics its difficult to suggest where the mould/damp signs are coming from?
Damp can penetrate from outside even with cavity walls.
I wasn't suggesting rendering, in fact, I would avoid rendering if possible.

 

[JohnD]

this is damp at the top of a stairway.

So ventilate the stairwell at the top.

Water vapour is lighter than air so it will rise up until it either escapes, or finds a cold surface to condense on.

 

[low drains drifter]

Without seeing pics its difficult to suggest where the mould/damp signs are coming from?
Damp can penetrate from outside even with cavity walls.
I wasn't suggesting rendering, in fact, I would avoid rendering if possible.

I'll get some photos

 

[low drains drifter]

Without seeing pics its difficult to suggest where the mould/damp signs are coming from?
Damp can penetrate from outside even with cavity walls.
I wasn't suggesting rendering, in fact, I would avoid rendering if possible.

why would you avoid rendering?

 

[low drains drifter]

photos from the stair area

 

[low drains drifter]

photo at the top of the stairs

 

[Harry Bloomfield]

this is a rental property. the mould is in the stairwell, so there is no room to put clothes there. But yes, this can be a problem where the property is "sealed" with double glazing and is heated with a gas boiler.

The moisture from drying clothes and cooking, can spread from other rooms, to condense on cooler surfaces. Especially, the steam from cooking, can rise up stairs, to find a cool surface to condense out upon.