Strong smell of ammonia after plastering

[Annie]

Hi, We recently bought a 1900s terrace, and after removing old wallpaper and chimney breasts got most of the house replastered. Used mortar mix to fix up some of the worse gaps in the brickwork before the plasterer came, and in one of the downstairs rooms near where the chimney breast had been removed noticed that a really strong ammonia type smell came out of the walls where we'd done this. When dry the smell went.

Plasterer came in to do that room and the smell came back again - he said he thought it may be where they'd had animals in the past, but I wasn't convinved after noticing the reaction with the mortar mix before - especially as it had happenend nearer the top half of the wall.

Nearly five weeks later and the room still smells of ammonia in the corner where I'd originally noticed it. Haven't yet painted that room, and worried there may be a bigger problem somewhere.

Google searches turned up the fact that soot mixing with cement can cause ammonia type smells - and this was the room where there was most sooty brickwork on the wall behind the chimney breast. The back of this wall is still covered in soot now (this is in the cupboard under the stairs, which we haven't yet plastered).

So my question is, if this is just a reaction of something in the plaster with the soot, will it go completely given time? Or do we need to do something to somehow neutralise the smell first before painting? Also planning to plaster the cupboard under the stairs. Is this a good idea? Will it solve the problem by trapping all the smells inside? Would plaster boarding the cupboard be a better idea so the plaster doesn't come in direct contact with the sooty bricks? Really not sure they could be cleaned as they're not in good condition, and it seems like the soot has penetrated them completely.

Any advice much appreciated?

 

[flynnyman]

Its when water comes into contact with soot you get the smell of amonia, if the cupboard doesnt have a vent the moisture in the air will be like adding water to the soot so giving the smell of amonia, Just a guess

 

[Annie]

Thank you for your comment. No, the cupboard doesn't have a vent. Or a door at the moment - just open to the same room where the smell is.

So if the smell is the soot reacting with moisture in the air, or water still drying out of the plaster, will this smell eventually disappear? Just wondering whether I need to take action in some way?

 

[andyR]

Id assume it would once the plaster is dry, if its the soot causing the smell.

 

[warriorupnorth]

He should off brushed off the soot and neutralized it with an inhibitor/neutraliser then applied the render with a salt inhib and waterproofing additive, some times a damp course is required esp in older buildings (big bone of contention on here) i'm on my mobile in India at the min so difficult to go into detail n specs but e-mail me an I will gladly give you as much I.
Info as I can when I get back , but there will be lots more opinions in this thread to follow, just glean what you can

 

[henry]

Yes good advice of warrior, the only thing I may just say is use a anti sulfate cement with the sand , what I have also seen brown staining from the soot. PVA can sometimes smell on different wall surfaces.

 

[Capital spread]

He should off brushed off the soot and neutralized it with an inhibitor/neutraliser then applied the render with a salt inhib and waterproofing additive,

Before you plaster you must scrub as much of the soot off as possible and then treat as above.
Failure to do this will not only cause the smell but in time the soot will bleed back through the plaster.

 

[irish_spread]

You could try tanking it with a watertight membrane, loads of companies on the market such as oldroyd ets then render with sovereign render mix or similar

 

[tboy]

had this 'smell' with hardwall, it was someone pissing in the water butt.:RpS_mellow: