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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> Bubbling Plaster https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1376079511 Message started by Smithy2000 on Aug 9^th, 2013, 9:18pm

Title: Bubbling Plaster
Post by Smithy2000 on Aug 9^th, 2013, 9:18pm

Hi there,

We live in a 160year old Victorian Cottage.
I have noticed sections of internal walls where the plastering appears to be bubbling and turning into sand.

Some of it is behind lining paper and some is bare plaster (with paint on top) just turning into what I can only describe as a crystalised type of sand.

I'm not sure if this is a damp issue or whether it is some kind of reaction, possibly with the old plaster or pointing being possibly of lime due to the properties age?

The house as been extended back in the 80's and that part of the house does not have this problem at all.

I did convert the under stairs area of the old section of the house to be used as a pantry. I took the walls back to brick and re-pointed the sections that needed it with a standard motar mix. I then boxed it out with plasterboard using dot and dab. I then skimmed the board before painting with white emulsion and fitting shelving. However a year on, I am now noticing some small sections of the skimming plaster is crumbling off, leaving little piles of powder on the floor.

If anyone could advise on what this is, what's causing it and how best to remedy it, I would be very grateful.

Cheers!

Title: Re: Bubbling Plaster
Post by TIMBA-WOLF on Aug 9^th, 2013, 10:31pm

can you provide a picture or 2 and check out this thread

http://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1364473698

Title: Re: Bubbling Plaster
Post by Smithy2000 on Aug 11^th, 2013, 12:15pm

Hi Timba-Wolf,

I've done some more research and believe the issue under the stairs is merely the emulsion flaking off has I didn't leave the plaster long enough to dry before painting it. AND I didn't use a 50/50 water and matt emulsion mix to prime the plastereed surface after it had dried out either! Damn! :o(

However the other issue remains, regarding the crystalisation of plaster / sand.

Bit more info / background:
About six months after we moved in and when the weather started getting really cold, we started getting black damp spores on the internal side of the house's north facing front external wall. Mainly in the dining room. Upon checking the house paperwork we found out that a previous owner (who was a builder and coincidentally built the rear extension back in the 80's) had the house treated for or against damp. This included as well as drilling the walls and injecting them to protect from rising damp, also had a real solid concrete type of plaster applied to a height of 1 metre interanlly around all the external walls of the old section of the house.
We had the Company that carried out this work inspect the spores as their work was still covered under a 30 year guarantee (now expired). They informed us that it was a condensation issue and we have since resolved this issue by installing a better electric heating system (we do not have mains gas) and ventilation.

Whilst viewing the black spores, I also asked him to look at a section of this crystalising issue that was on the base of a brickwork pillar about 8inches above floor level, around the door frame that led to the space under the stairs.

He looked at it and said that he knew what it was but wouldn't go into great deal about it or how to resolve it has he said "If I tell you what it is and how to resolve it, you'll just sort it yourself and that will take business away from his company resolving it". ??!!

Anyway, I din't give him any busniess but when I came to converting the under stairs space, I merely knocked out the brick that were suffering from this crumbling and crystalising and two more surrounding bricks to make sure and replaced them with reclaimed bricks (due to the old sizing) and that seemed to resolve the issue.

However the piece that we've now noticed crumbling and crystalising behind the lining paper, is just above this pre mentioned 1 meter protection mark on the front house wall and located in the downstairs loo. Yet sections within 10 inches around it appear solid and dry as confirmed by a damp meter. There is a window within a foot of this section and we also have plantation outside this window (in the ground not in pots and been there for possibly years before we moved in 3 years ago).

So, am I looking at potentially another damp crumbling and crystalising brick that needs to be replaced or is this something potentially more serious?

Cheers and I will see if I can get some pics sorted, after I've ripped off some of the lining paper for better access / viewing.