Damp Issue - TilersForums.com

[RDTiling]

Hi all.

I went to look at tiling a bathroom the other night. The bathroom has been treated for dampness issues, they have had the DPM replaced and the walls were replastered about 4 weeks ago.

First thing I spotted was some black dots on the new plaster (pics attached)

The only times I've ever seen those are where there are damp issues. Anyone got any thoughts or am I on the wrong track?

I'm reluctant to just tile over them, given dampness was the reason it was ripped out in the first place!

 

[White Room]

You say replastered but with what???

 

[RDTiling]

Its a smooth finish and feels a lot like multifinish.

The owner told me where the key was so she wasn't aroud when I was there.

I unfortunately don't know whether they use a bonding plaster first.

I said to her on the phone that I'd never seen patches like that on new plaster!

 

[White Room]

If the dpm had been replaced they shouldn't be using any gypsum based products for the floating coat (undercoat), multi finish is standard.

The floating coat should a cement based as Sovereign Renderlite which stop salt coming through, the spotting looks like there's no ventilation in the bathroom.

 

[RDTiling]

There is a vented window in the bathroom, but perhaps its not enough.

Do you think it would be ok to tile over or should i suggest looking into it further?

 

[Ajax123]

Treated for damp..... Was it dried to remove the damp that was already there?? The dots don't look like mould but I am really not sure what they are. It might be mineral deposits as a result of efflorescence. I guess it could be a one coat plaster which will have larger mineral aggregates in which could come to the surface on finishing.

 

[widler]

Looks more like mould coming back through,or its that badly vented it just has bad condensation, is it a council house ?

 

[Rizzle from the Portizzle]

Looks more like mould coming back through,or its that badly vented it just has bad condensation, is it a council house ?

snob

 

[Rizzle from the Portizzle]

ok damp cannot rise that high as gravity will not surport the weight of water at that hight so if its damp its coming in from an out side source and finding the weakest point to show its self .so only two options walls out side letting in water from over flowing guttering .or leak from flat above .if its building from bad venting on the inside it will only be on the surface not behind so scape back a couple o mm then damp test .

 

[widler]

snob

Right im a snob ray, im from burnley, proper posh up here

 

[RDTiling]

Thank you to all for your input.

The property is an older building (i think from memory the brick plaque above the main door read 1903) of 6 flats and this one is on the ground floor.

All the owner me is that a specialist damp proof company was brought in to rectify the problem.

I've not heard back on the result of the damp proofing company coming back to look at the 'spotting' on the new plaster.