Spores appearing after newly plastered wall

Top Gun Andy

New Member
Hi all, Newbie here.

I have very recently had an internal garage conversion completed on 14 year old detached house. The long external wall was insulated with 50mm celotex boards, drylined and then skimmed. 3 of the 4 walls were complete well over 2 weeks ago and the plaster has dried out nicely. However, today we have noticed (ahead of painting luckily) that, what look like, spores have appeared all along the externally plastered wall. It is worse nearer the window end of the garage.

Before contacting the builder I would like to get some advice from this forum to see what peoples opinion is on what the cause might be. This is going to be my daughters bedroom so the last thing I want to do is wipe off, patch over and hope it doesn't return if it is mould.

Cheers
 

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Top Gun Andy

New Member
Cavity external wall and yes there is 50mm Celotex on the walls (I have photo evidence). The builder did start boarding without but I was at home and got them to pull it off and then building control told them it needed to be 50mm insulation.

Builder has come round and we asked a friend in the trade who said that it could be the salts coming out of the plaster. Builder has advised wiping off with bleached solution. We will do this and leave for a few days to see if this returns. I will borrow a dehumidifier as well.
 

Vincey

Private Member
Tbf did think this is sounding like something not right but had this once myself , can I ask did you ever open the windows in that room at all from when the room was plastered
 

brimplas1

Well-Known Member
I have had it on a shop refurbishment recently but that was due to slow drying, it had no heat and no ventilation.... All the beads were rusting.... I wouldn't use bleach i would get a specific mould sterilizer....
 

tapit

Well-Known Member
Cavity external wall and yes there is 50mm Celotex on the walls (I have photo evidence). The builder did start boarding without but I was at home and got them to pull it off and then building control told them it needed to be 50mm insulation.

Builder has come round and we asked a friend in the trade who said that it could be the salts coming out of the plaster. Builder has advised wiping off with bleached solution. We will do this and leave for a few days to see if this returns. I will borrow a dehumidifier as well.
It does not look like salts. you would usually get a white powder appear on surface.
 

worthwords

Member
what temp in the room and any ventilation?

Drying plaster produces a lot of humidity while the colour changes to pink and it will tend to condense on the coldest surface - which will be the slowest drying (probably external) wall which is still evaporating.
If you take out the radiators in a room you have to bear in mind that cold air can't hold much moisture so it more readily dumps the water on surfaces.

Mold spores are in the air normally so it's about creating an environment which is favourable for them to grow (low temperature and high humidity). The fix is to address those factors and deal with the surface mildew with cleaner.

You can't suck salts though celotex!
 

Dollar

Well-Known Member
Begs the question
you caught.him not putting insulation in
Rule 9 plasters rule book is instantly to chuck the dirty animal out on the street ,
Can of worms springs to mind know with issue

Your welcome
 

choppa

Well-Known Member
Hi all, Newbie here.

I have very recently had an internal garage conversion completed on 14 year old detached house. The long external wall was insulated with 50mm celotex boards, drylined and then skimmed. 3 of the 4 walls were complete well over 2 weeks ago and the plaster has dried out nicely. However, today we have noticed (ahead of painting luckily) that, what look like, spores have appeared all along the externally plastered wall. It is worse nearer the window end of the garage.

Before contacting the builder I would like to get some advice from this forum to see what peoples opinion is on what the cause might be. This is going to be my daughters bedroom so the last thing I want to do is wipe off, patch over and hope it doesn't return if it is mould.

Cheers
Should of used vapour board
 

Robbo123

Well-Known Member
Begs the question
you caught.him not putting insulation in
Rule 9 plasters rule book is instantly to chuck the dirty animal out on the street ,
Can of worms springs to mind know with issue

Your welcome
Agree, he should of known the spec needed and shouldn't need to be told. Also how is the ceoltex attached? I did the same with my garage and built stud walls in from the brickwork with 50mm celotex in-between and 25mm over the top
 

bof

Well-Known Member
Flicking water on skim is a no no
Flicking from a bucket of bacteria is only excusable if the customer has an affliction to switching the kettle on

Just thought the pattern showed bacterial rings from contamination spots , which could have been on the board already TBF
 

The Hobo

Well-Known Member
Flicking water on skim is a no no
Flicking from a bucket of bacteria is only excusable if the customer has an affliction to switching the kettle on

Just thought the pattern showed bacterial rings from contamination spots , which could have been on the board already TBF
kind of thinking down them lines last night /where had boards been stored prior to use
 
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The Hobo

Well-Known Member
Flicking water on skim is a no no
Flicking from a bucket of bacteria is only excusable if the customer has an affliction to switching the kettle on

Just thought the pattern showed bacterial rings from contamination spots , which could have been on the board already TBF
just been back on photos look at right hand side were there is a cut board the mould is on the top board but stops at the joint so is not coming out of the room its on the boards before the fixing /I would go for damp storage before fixing
 

bof

Well-Known Member
just been back on photos look at right hand side were there is a cut board the mould is on the top board but stops at the joint so is not coming out of the room its on the boards before the fixing /I would go for damp storage before fixing
Probably , didn't look too closely tbh , small screen phone , would still suspect the contaminated spots playing a part from growth rings like in Petri dish at school
 

Robbo123

Well-Known Member
just been back on photos look at right hand side were there is a cut board the mould is on the top board but stops at the joint so is not coming out of the room its on the boards before the fixing /I would go for damp storage before fixing
Good spot. Yeah you're right, stops exactly on the board edge. Must have had mould on when they were installed
 

bof

Well-Known Member
Case closed, nice one guys. What is a peter dish?
The little flat round lidded dishes to grow or Test bacteria for multiplication
 

John j

Mono Don
just been back on photos look at right hand side were there is a cut board the mould is on the top board but stops at the joint so is not coming out of the room its on the boards before the fixing /I would go for damp storage before fixing
Why i asked who got the boards. Builder was gonna put standard boards on till he got pulled. Then relised he has to put 40 pound a piece boards on . But wait a min he got some at back of garage from 3 years ago
 

Stevieo

Royal Spin Doctor
Flicking water on skim is a no no
Flicking from a bucket of bacteria is only excusable if the customer has an affliction to switching the kettle on

Just thought the pattern showed bacterial rings from contamination spots , which could have been on the board already TBF
Just a guess but I'd say @Pam H was probably kidding
 
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