Mould or Damp issue

[Jeremy2014]

Looking for expertise here

A damp issue was repaired which was caused by gutter leaks which resulted in one small area of the internal walls to bubble and paint flaking off.

I have scrapped the loose paint and apply filler and repainted.

but now couple of week later, as you can see the paint is powdering, flaking off again - and looking the same as before if not worse.

Talk to some mould people and they say they can fix it for 800 + Vat with the usual scary mould speech.

But question is that just damp that need to be sorted properly? or mould that need to be treated?

So thinking to get dehumidifier , heating so to dry the surface as much as possible.
Do I need to apply any treatment to the wall, once the surface clear / clean - Something like or alternative product? or is there anything else I need to consider please?

Zinsser Bulls Eye 1-2-3 Primer-Sealer White 1Ltr​

 

[Koolpc]

You may need for it to fully dry out if the leak has only recently been sorted. Walls can hold moisture.

 

[Murdochcat]

Walls can hold moisture.

sometimes for months.

Constant ventillation is the key - for a few weeks

 

[foxhole]

Had a gutter leak resulting in a small area showing damp, took 18months for the surface to stabilise .
Best to leave paint off till its stable.

 

[Jeremy2014]

Had a gutter leak resulting in a small area showing damp, took 18months for the surface to stabilise .
Best to leave paint off till its stable.

What did you do to get it stabilize? Just let it dry? any treatment before to paint or prepared the area?
How would you know it is stable?
Can you measure humidity in the wall with fancy gadget / tool from Amazon?

 

[opps]

You seem to have efflorescence, namely salts in the plaster rising to the surface. Those salts are pushing the paint away.

You can buy salt neutralisers

Salt Neutraliser 1 Litre | Rempro

Salt Neutraliser is a water-based formulation designed to penetrate the surface of interior walls Creates an insoluble barrier against further salt movement onto the surface Apply Salt Neutraliser treatment by brush or roller to areas showing salts contamination Salt neutraliser can be applied...

www.rempro.co.uk

No point until the plaster is dry though. As others have stated, air flow is key but a dehumidifier will help. Damp meters are great for timber but useless for plaster. The meters are basically finely calibrated resistance meters. The salts increase the electrical conductivity meaning that damp meters often still show damp even years later.

 

[foxhole]

What did you do to get it stabilize? Just let it dry? any treatment before to paint or prepared the area?
How would you know it is stable?
Can you measure humidity in the wall with fancy gadget / tool from Amazon?

As oops stated damp meters are for timber , damp in walls can be measured but requires kit to drill the wall and place dust sample in a pressure chamber to asses moisture content .The moisture content on surface is of no consequence .I sanded and waited for salts to stop leeching out.

 

[Jeremy2014]

Thanks all for your feedback - greatly appreciated. Patience is key to let it dry properly and then apply Salt neutraliser before to paint again is the plan of action.