problem with black mould building up walls, ceiling

brendankelly

gsxr1 wrote: »

Why are you asking a question about an unoccupied building?

The OP lives in an occupied home.

If you are having problems with an unoccupied house why not start a thread on it. Im sure we can help you.;)

Thanks for the offer of help but I do not have any problems with damp Thank God. From reading the advice here if I had dampness I would have to keep the windows open, Could not have a shower, could not boil the kittle and the bit of sex would be completely out. Thank God I do not have dampness.

paddy147

Lads leave it out will yous,and less of the smart ar5e answers too.:rolleyes:

Everyone is doing their bit to help out here,so dont start whinging on or giving out about the advice given out.

gsxr1

brendankelly wrote: »

Moisture will only condense on a wall if the wall is colder than the temp of the room. If a wall is colder than the temp of a room then there is a problem with the wall. When condensation appears on a wall it means that there is what is called ""cold bridging"". This is where there is something that will carry the cold from the outside to the inside of the wall. In stone builds this was the ""Through Stones"" they became known as weeping stones by those that did not understand or by the builder that was trying to cover up for his bad workmanship. Moisture condensed on the Through Stone and flowed down the wall. ""Weeping Stone"". The problem the OP has is with the wall.

Oh. So its not down to a leak then?

Its weeping stone ?

brendankelly

You clearly never heard of weeping stones and I cannot say for definite that it is not down to a leak.

A cold bridge could be any thing for example a dirty wall tie could be a cold bridge. An air pocket in the cavity insulation could be a cold bridge. I have seen the window DPC in a ball at the top corner of windows causing a cold bridge.

If the wall is colder than the room temp there is a problem with the wall.

BostonB

MicktheMan wrote: »

...

Very often and in my experience, Landlords experience damp problems in their properties when certain tenants move in and then when the tenants are replaced with other tenants the damp problems subside. In your case this may not be the case but it is worth bearing this in mind. ....

A friend had this. Previous tenants in the house 5 yrs no issues. New tenants in the house 2 months and had lots of mould. Tenants leave, new tenants no mould problem.

One place I see mould a bit is in bathrooms/shower rooms with no windows, just extractor fans. The fans can't clear the humidity quick enough.

gsxr1

BostonB wrote: »

A friend had this. Previous tenants in the house 5 yrs no issues. New tenants in the house 2 months and had lots of mould. Tenants leave, new tenants no mould problem.

One place I see mould a bit is in bathrooms/shower rooms with no windows, just extractor fans. The fans can't clear the humidity quick enough.

yeah. I find this also.

One apartment is as dry as a bone with 2 people living in it. The same apartment one year later with 4 people in it is a damp cave.
We are working with homebond trying to find why. We suspect cold weather and constant sauna like conditions, due to clothes drying and over crowding is the cause. Lack of sun on a cold north wall all this can come together to make trouble.

The air is thick to breath. . It really does come down to a moisture balancing act. Even in a place that is built to standard.

Before one tears down or replaces this and that. Understanding how to control the simple causes is paramount. OP it could well be anything as this thread shows . I think you need to get up there and trace the source whether it be leak or simply condensation.

Brenden . You seem to be upset as I sided with Mick. I believe his solutions to be the simplest to cover before considering building defects . It is always advisable by me to not make a mountain out of molehill. Im sorry if this upsets you. I do understand how this happens. Its my job. I have found that that a simple adjustment in climate cures the problem.

BostonB

A leak would cause other problem, like staining before mould I'd expect. Though obviously it would cause mould eventually.

AMG86

Have a look at this link. http://www.proair.ie/index.php?option=com_content&task=view&id=63&Itemid=209. Installation of a HRV system could go some way in solving your problem.

brendankelly

Apologies all aound but if I had not seen it with my own eyes I would not have believed it. Glazed plastering can and will cause damp spots on wall and ceilings. The person that leaves glazed plastering should not be called a plasterer, The site manager that did not cop it was blind and the person that painted it was not a painter..

Skimming should be applied in 2 coats. When the first coat is ""going off"" the second coat is applied. The drying out process causes suction and this in turn makes the second coat porous. Gypsum is not very breathable but glazed skim is the same as glass and condensation will form on it. Glazed plastering is actually a special finish and was asked for in the early 70s for in toilets over the tiles. The idea was that it could be easily washed and would not keep smells. Glazed plastering can only be achieved by applying one coat and troweling it while it is wet.

gsxr1

brendankelly wrote: »

Apologies all aound but if I had not seen it with my own eyes I would not have believed it. Glazed plastering can and will cause damp spots on wall and ceilings. The person that leaves glazed plastering should not be called a plasterer, The site manager that did not cop it was blind and the person that painted it was not a painter..

Skimming should be applied in 2 coats. When the first coat is ""going off"" the second coat is applied. The drying out process causes suction and this in turn makes the second coat porous. Gypsum is not very breathable but glazed skim is the same as glass and condensation will form on it. Glazed plastering is actually a special finish and was asked for in the early 70s for in toilets over the tiles. The idea was that it could be easily washed and would not keep smells. Glazed plastering can only be achieved by applying one coat and troweling it while it is wet.

I also have seen this. I think. It looks like a map on the wall after emulsion paint has been applied. Like a polished finish in parts.

starlight09

brendankelly wrote: »

I have worked on hundreds of houses and I never saw a damp spot on a ceiling that did not have a leak above it in the felt/roof. It is the same for the walls. If the outside plaster is cracked you will have a damp wall inside unless it is a cavity wall that is vented. Water tanks are often placed above bathrooms and condensation will form on the outside of tanks and pipes that becomes water when it hits the plasterboard.

Hi Brendan,
I' m interested in what you said. We have a problem with vapour like drops on our ceilings and running down the walls also patches of black mould, for this I use mould and mildew which works great but only for a time. We live in a bungalow, we had the external walls pumped 2yrs ago, made no difference. over the years I have tried all kinds of things, special paint, (waste of my money) opening windows, closing windows, keeping the house warm. We were told to make sure attic insulation was going out properly at the edges which we took care of. We are totally at a loss. Its easy for some people to say that its normal in winter but when it affects wardrobes and ones health, we have to do something. Our bathroom is tiled but still water flows so badly down the walls that the window sill and floor are soaked each morning. I also notice that the outside of the cistern is full of condensation and dropping on the floor. Sorry for going on I'm just so tired of having to mop up every day. My husband says to ask would the soap-block have anything to do with it. Hope you can help.

DCCC

trixyben wrote: »

I have a house that I rent out and im having a problem with black mould around the top a windows and random patches on the ceilings, up stairs, i had window vents put in all up stairs windows to help air ventilation but to no avail, anything that is up against one o the bedroom walls ater a while will start to grow mildew on it...

This has been a problem or a while now and want to get this sorted i thought maybe cavity insulation was maybe needing reilled but had this checked and its OK..

Has anyone had problem with similiar and how did you solve the problem?

cheers

hi
sound like trap water in cavity. if your house is bricks make sure weep holes are installed above all external opt. This should do it
if this doesn't work have a builder take a look you should be able to get a free Quot
Best of look

johnb25

starlight09 wrote: »

Hi Brendan,
I' m interested in what you said. We have a problem with vapour like drops on our ceilings and running down the walls also patches of black mould, for this I use mould and mildew which works great but only for a time. We live in a bungalow, we had the external walls pumped 2yrs ago, made no difference. over the years I have tried all kinds of things, special paint, (waste of my money) opening windows, closing windows, keeping the house warm. We were told to make sure attic insulation was going out properly at the edges which we took care of. We are totally at a loss. Its easy for some people to say that its normal in winter but when it affects wardrobes and ones health, we have to do something. Our bathroom is tiled but still water flows so badly down the walls that the window sill and floor are soaked each morning. I also notice that the outside of the cistern is full of condensation and dropping on the floor. Sorry for going on I'm just so tired of having to mop up every day. My husband says to ask would the soap-block have anything to do with it. Hope you can help.

We have similar problems in our en-suite, worse in winter. The main cause is the steam from the shower, which condenses on the walls, especially the external wall. Once condensed it is almost impossible to clear. It is worst near the top of the walls where the cavity is closed, and around the window. In cold, frosty weather leaving windows open is almost useless, as there is almost no breeze or air circulation, and it cools the room. The en-suite has a 4" wall extractor which cannot cope with the steam from two showers in the morning.

I am going to put in a ceiling extractor directly over the shower to try and get the steam extracted before it has a chance to circulate and condense.
The standard 4" shower ceiling fan is something like this http://www.tlc-direct.co.uk/Products/MRSL100TC.html which has a capacity of about 85m³/hr.
What I am looking at is something like this, http://www.tlc-direct.co.uk/Products/SLTD250T.html which has a a capacity of 250m3/hr
Does anyone see any problem with using a fan of this capacity? Is there any reason why I could not do this?
The existing wall fan runs of the light switch, and has an isolator switch. I presume I can tap into this and operate it from the light also? (Will get spark to do it!)

starlight09

Johnb25,
I agree completely with you about opening windows in frosty weather, its a total waste. If you go ahead with 1 of those fans would you please post here how it works for you. It could be an answer to one of my problems. Best of luck with it.

brendankelly

I have a theory on this. Condensation will form on the glazed plastering because it is like glass. What I would like to do is plaster one wall with lime putty and see how much less condensation will form on that wall compared to the other walls. I do not expect that one skim coat of putty will be enough. Naturally I could not charge for experimenting on someone's house so if there is someone out there that is adventurous within range of me get in contact.

johnb25

brendankelly wrote: »

I have a theory on this. Condensation will form on the glazed plastering because it is like glass. What I would like to do is plaster one wall with lime putty and see how much less condensation will form on that wall compared to the other walls. I do not expect that one skim coat of putty will be enough. Naturally I could not charge for experimenting on someone's house so if there is someone out there that is adventurous within range of me get in contact.

Can it be painted over? Will a coat of bathroom emulsion over the lime putty not put a sheen on it again, and back to square one? Surely it is more to do with temperature.

starlight09

On the subject of dampness and black mould, I was told today to paint my room walls with Zinsser B-I-N Primer. It dries into a flat white ready for painting. Has anyone heard of this? Does it work or am I wasting my money again? What about any health hazards? Feedback welcome.

BostonB

johnb25 wrote: »

We have similar problems in our en-suite, worse in winter. The main cause is the steam from the shower, which condenses on the walls, especially the external wall. Once condensed it is almost impossible to clear. It is worst near the top of the walls where the cavity is closed, and around the window. In cold, frosty weather leaving windows open is almost useless, as there is almost no breeze or air circulation, and it cools the room. The en-suite has a 4" wall extractor which cannot cope with the steam from two showers in the morning.

I am going to put in a ceiling extractor directly over the shower to try and get the steam extracted before it has a chance to circulate and condense.
The standard 4" shower ceiling fan is something like this http://www.tlc-direct.co.uk/Products/MRSL100TC.html which has a capacity of about 85m³/hr.
What I am looking at is something like this, http://www.tlc-direct.co.uk/Products/SLTD250T.html which has a a capacity of 250m3/hr
Does anyone see any problem with using a fan of this capacity? Is there any reason why I could not do this?
The existing wall fan runs of the light switch, and has an isolator switch. I presume I can tap into this and operate it from the light also? (Will get spark to do it!)

I've tried unsuccessfully to get a larger fan, my local electrical supplier being utterly useless I gave up chasing them for it.

We have the same problem en suite.

I was wondering, is there a better way to contain the steam. Having a seal ceiling to floor door on the shower and some sort of passive plastic hood over the shower to funnel the steam into some sort of trap, that drains back to the shower tray. An alternative I suppose is some form of wet room, though I don't know if the ceiling is water proofed in that scenario.

Fans I think just delay the problem rather than cure it.

starlight09

brendankelly wrote: »

You clearly never heard of weeping stones and I cannot say for definite that it is not down to a leak.

A cold bridge could be any thing for example a dirty wall tie could be a cold bridge. An air pocket in the cavity insulation could be a cold bridge. I have seen the window DPC in a ball at the top corner of windows causing a cold bridge.

If the wall is colder than the room temp there is a problem with the wall.

As I have mentioned here, we suffer from black mould patches in our room walls, we thought it might be from dirty wall ties as you mentioned so we had the walls pumped with insulation 2yrs ago but it did no good unfortunately. In cold weather the top of the walls (from ceiling) have droplets of water running down. Any ideas Brendan.

The black patches will not come off with just water so I don't think its condensation. These patches are in the area running along over the windows but I did see in one of the rooms where I removed the carpet that the corner floor and skirting board was wet to the touch with a fowl smell.

johnb25

BostonB wrote: »

I've tried unsuccessfully to get a larger fan, my local electrical supplier being utterly useless I gave up chasing them for it.

We have the same problem en suite.

I was wondering, is there a better way to contain the steam. Having a seal ceiling to floor door on the shower and some sort of passive plastic hood over the shower to funnel the steam into some sort of trap, that drains back to the shower tray. An alternative I suppose is some form of wet room, though I don't know if the ceiling is water proofed in that scenario.

Fans I think just delay the problem rather than cure it.

I am hoping that the second fan I linked to above will extract the steam almost as quickly as it rises, and therefore nip the problem in the bud.
Another thought that crossed my mind was to fit a glass panel above the shower screen that would stop steam travelling along the ceiling. I would leave a gap between between it and the shower screen to allow an inflow of air for the fan.

tlc, linked to above, deliver to ROI. I have never dealt with them, but they look like a large enough outfit.

johnb25

starlight09 wrote: »

As I have mentioned here, we suffer from black mould patches in our room walls, we thought it might be from dirty wall ties as you mentioned so we had the walls pumped with insulation 2yrs ago but it did no good unfortunately. In cold weather the top of the walls (from ceiling) have droplets of water running down. Any ideas Brendan.

The black patches will not come off with just water so I don't think its condensation. These patches are in the area running along over the windows but I did see in one of the rooms where I removed the carpet that the corner floor and skirting board was wet to the touch with a fowl smell.

Our condensation is also worst along the top of the exterior wall. The reason for this is cold bridging; there is a cavity closing block that sits on top of both the outer and inner leaves of the wall, maiking this is the coldest part of the wall. Yours is probably the same.
Condensation causes mold, which will not wash off with water or more condensation.

gsxr1

Condensation can not form is there is a absence of air. Makes sense.

That accepted.

mushroom fixing 50mm insulated plasterboard should prevent internal condensation from forming on the surface of the wall behind it. Air cant condensate in zero air space.


People with problem cellars with waterproof concrete wall solve condensation by the use of sprayfoam. This also eliminates the air gap and creates a warm surface .

Any thoughts

brendankelly

My Idea If you look at a gas bottle outside of a frosty morning you will see a ring of frost up to the level of the gas inside. This is condensation. Your wall is now the gas bottle and it is colder than the air inside and condensation will form on it. You have cold bridging. If the wall ties caused the cold bridge the pumped insulation made it worse. It definitely did not stop it.

I will PM you the name of a material that would (I am 80% sure) solve your problem but it is 60 E per Sq Meter just to buy. The other idea is to put a good lime plaster on the outside but because your walls are so wet it would take ages to dry especially over cement blocks. Lime plaster allows moisture in and vaporises it and it comes out as vapour. This process heats up the wall and because the wall would be just a fraction of a degree warmer than the air condensation will not form on it. We have been looking at this problem for years and doing small tests and so far we have found that using lime has had the most success. But unfortunately at present we cannot tell you that putting x amount of lime plaster on will absorb y amount of condensation.

heinbloed

Seldom one hears such rubbish:

Quote from the salesman posting above:

" Lime plaster allows moisture in and vaporises it and it comes out as vapour. This process heats up the wall and because the wall would be just a fraction of a degree warmer than the air condensation will not form on it. "

The laws of physics?

Evaporation COOLS surfaces, lime plaster salesman ! Not the other way around !
The world woudn't have to bother about home heating, just a spray of water onto walls and the house is warm...oha.

The colder the surface the wetter it gets. Due to the increased temperature difference.
Back to school , lime plaster salesman !
Consumers be aware of the cowboys!

Since the realative air humidity is higher outside than inside one doesn't need direct rain to see the wall getting soaked. The airborne moisture is enough to wetten a lime plaster wall beyond any suitability for human usage.
In the Irish climate, with an average air moisture of more than 80% the wine cooler effect build into an external wall, yeassus, one must be really stupid .....

heinbloed

Why are evaporating walls cold ?

For many people this is mystery, abused by the cowboys of the building trade.

There is an ancient method to keep things cool, without a mechanical or chemical support an item can be kept about 5 degrees Celsius colder than it's sorrounding air.
We can buy these devices in the clutter shop, for example for cooling butter or wine. A simple clay container would be soaked in water and the evaporating moisture cooling down the content.

Like this one for example:


http://www.fine-wine-accessories.co.uk/productdetails.asp?productid=76

Someone who sells evaporating materials to the home builder and claims they help to keep the wall warm should be taken off the market and put behind bars. Into a cell, one with damp walls and no other form of heating. That might teach him a lesson.
Anyone here who is willing to inform the authorities about the lime plaster salesman his methods?

gsxr1

I do believe that it is widly regarded that lime plaster as apposed to cement bace plaster is warmer.
http://www.heritage-house.org/condensation.html

This is a fantastic example of condensation in a corner of a bedroom. It had formed on one wall, causing damp, mould, fungus - you name it. We scraped the paint and fungus off, to expose cement render on brickwork. It doesnt go round the corner to the wall on the right.

I wonder why?

We tested the temperature and humidity of the walls. The wall on the right is covered with original lime plaster. The temperature probe showed a temperature of almost 2 degrees higher for the lime plaster than the wall with the mould on it - which was cement rendered and nearly 2 degrees colder.

Another example of how modern materials dont work, and traditional materials are warmer and drier.!

I have heard this before. In the trade.

I am not a sales man . Lime plaster was widely used in older building practices and is quite common in older homes.

You may be interested in the above link.

I dont believe the OPs problem to be any more than internal condensation TBH.




Condensation is the result of warm, moist air which finds a cold surface on which to condense. The two coldest places in a house are generally the windows, and the bottom of the outside walls, near the skirtings. Moisture comes from a variety of sources, but mainly:

We humans – the average human sweats and loses around 8 pints of water in a 12 hour period
Kitchens – cooking – steam from hobs and ovens, tumble dryers
Bathrooms – showers, baths, wet towels
Plants – in pots on window ledges
Wet cellars with no ventilation or air circulation
One of the things we often see in old houses, is water streaming down windows in winter and collecting in pools on the window ledge. This is because the rooms are not able to breathe – the air is not circulating and able to get away, and the warm, moisture laden air thus releases moisture on the windows. The commonest problems with old houses that stop air circulation are listed below:

Installation of plastic (UPVC) windows with no ventilation
Ventilation bricks blocked up
Fireplaces blocked up with no ventilation
Draught excluders around doors
Lack of ventilation to cellars
No extractor fans to kitchen and bathrooms

brendankelly

The German is in a bad humour today?. If he read my post
""the wall would be just a fraction of a degree warmer than the air condensation will not form on it. ". He would not need to write """The colder the surface the wetter it gets""".

You should look at the link from GSXR1 and read it. The only thing left out by GSXR1 is that there should be a working cavity.

starlight09

I've been googling and came across a company called HRV (heat recovery ventilation system) It looks good, really impressed with it. Just wondered if anyone has any know more knowledge on it.

MicktheMan

starlight09 wrote: »

I've been googling and came across a company called HRV (heat recovery ventilation system) It looks good, really impressed with it. Just wondered if anyone has any know more knowledge on it.

Yes, it works assuming:
1. your house is airtight
2. the system is sized correct for your house
3. the ductwork is optimised and properly insulated.

There are many companies offering hrv systems. The principle of its operation is moist warm air is extracted fron the wet rooms (kitchen, urility bathrooms, ensuites etc and a outside air is supplied to the other rooms (living, bedrooms) with the halls & corridors acting as buffers. This is the ventilation part (V). The heat recovery (HR) part is where the heat is taken from the warm moist extracted air and transfered to the cold outside supply air through a heat exchanger. The two air streams don't actually mix. A consequence of this process is that the supplied air is dried (from a RH% point of view).
It's designed to run 24/7.
You get a controller which allows you to boost the system when showering for instance and also to set it at minimum when occupation is low.
There is regular maintenance required in that filters need to be cleaned every couple of months and changed annually therefore location of the HR unit is important.
Not suitable with open hearths.
I have one installed in my house (a 35 yo bungalow) with airtightness less than 3ACH @50pa and has improved our internal air quality no end (used to have RH% >70% regularly and now it baselines at 40-45% peaking to maybe 55% when cooking in the evening.
To sum up, worth it big time in the right situation.

gsxr1

yeah have to agree. The HRV systems are very impressive. The quality of the air in the home is noticeable fresh, balanced and pleasant . A house I once built had it and I noticed the need for plenty of attic space for the ducting. It all looked very expensive to install in a new home. I would expect it would even more expensive to fit into a completed home.