Mould has returned whats the next step ?

westcountrycat · Post by **westcountrycat** » Thu Oct 17, 2019 11:23 am

Hi All,

We have an 1950's ex council semi detached, we have had a constant problem with mould in the smallest bedroom (two outside walls). it has a slight roof slope on the ceiling.

We have tried ventilation to the max, a de humidifier, airbrick, airholes in the soffits - none of that made a difference and just made the room very cold for my little boy and i had to get a extra rad in their in the end over winter, all that ventilation did't seem to make a difference to the problem.

other notes - Guttering has been done. its doesn't feel west to touch.

We have now tried keeping the room warm, new window, kingspan insulation down the sloped area (from inside the loft) where most of the mould occurred and no airbrick. The room is now warm and habitable and the mould is less prevalent than before so i thought we had cracked it however, ....... over the last two wet and damp weeks the mould has sprung up again, mainly in just one corner of one wall and along the top of another wall.

i have attached photos, i'm not sure if that helps any advice on what steps i should take next ?

: M2.jpg (33.46 KiB) Viewed 3206 times

London mike 61 · Post by **London mike 61** » Thu Oct 17, 2019 11:50 am

Have a look in the loft to see if there is any water ingress and lift the loft insulation above the bedroom and see what the area is like around that space. Also check hat the roofing felt is not torn or damaged as that would cause water to seep through.

Mike

westcountrycat · Post by **westcountrycat** » Thu Oct 17, 2019 12:32 pm

Thanks Mike, i think i'm going to get someone into have a look at your suggestion. thanks

sammy.se · Post by **sammy.se** » Thu Oct 17, 2019 1:36 pm

I had a similar problem - it turned out to be a couple of things - water ingress from guttering (which you have fixed) and secondly, moss had built up between two adjoining roofs, which was a moisture trap and was wicking moisture from the roof join, down to the wall, and into the room.

As per the above post, I would check the roof thoroughly.

Also - what is on the external wall? is it bare brick or rendered? and is the wall solid, or does it have a cavity?

westcountrycat · Post by **westcountrycat** » Thu Oct 17, 2019 1:46 pm

Hi Sammy,

it is a rendered wall, i understand it had cavity wall insulation a very long time ago.

I have just been cleaning it again and one of the walls it is on does feel a little damp and has some brown and black mould spots the other section of mould is on the other corner where there is one outside sidewall and one internal wall ajoining and this does feel to totally dry.

I terrified of the cost but know it can't go on :(

sammy.se · Post by **sammy.se** » Thu Oct 17, 2019 2:35 pm

Hmm. Ok, it could be that the render has blown and there is water between the render and the brick work, but, if it is a cavity wall, the outside skin/bricks shouldn't be transferring moisture into the internal wall, unless the cavity is breached (meaning something that wicks moisture is connecting the two skins of bricks).

I would say don't spend any money - you need a reputable damp expert's advice - hopefully some wiser people than me on here can provide it.

There's a really good expert on YouTube that explains things really clearly and shows a variety of damp situations - I'll try and dig up his name.

Don't worry - it will be solved. Don't spend any more money though, for now, unless it's getting someone knowledgeable to diagnose it

But, most damp 'experts' are not experts, that's the annoying thing...

It could be something like this: https://www.youtube.com/watch?v=QrjCRsA5jwM

I don't mean to scare you! Might not be this at all! just trying to describe how damp can occur in cavity walls...

sammy.se · Post by **sammy.se** » Thu Oct 17, 2019 2:36 pm

https://www.youtube.com/user/stibnite11

Peter Ward - you can learn a fair amount from his videos.

Rorschach · Post by **Rorschach** » Thu Oct 17, 2019 3:14 pm

That looks like condensation mould to me, very common in the corner of rooms. Is that a matt emulsion on the wall/ceiling? If so, re-paint the area with a silk finish mould resistant paint such as Zinsser permawhite.

Warmth won't stop mould, in fact it will only help it, dry is what you need. Ventilation only works if you are bringing in dry air, in the UK ventilation can serve to make things worse as the air is cold and wet. Getting the moisture out of the air is key, you have already mentioned a dehumidifier which is great but for it to work properly you need to stop damp air getting in, if you are ventilating at the same time as dehumidifying you are wasting your time.

sammy.se · Post by **sammy.se** » Thu Oct 17, 2019 4:24 pm

Hi Rorschach, do you think that the cold spots might be causes by an underlying damp problem, which then attracts the condensation?

Totally agree about the dehumidifier not being close to fresh air.

I'd be curious to know if the damp is present underneath the paint, and how deep it is. If it's dry under the paint, or maybe just damp for a couple of mm's, then I could agree it's condensation. If it's damp a few CM's into the wall, I'd be inclined to think there was another underlying issue...

Rorschach · Post by **Rorschach** » Thu Oct 17, 2019 6:46 pm

If there is water getting behind there I would expect to see a water stain and a lot more mould. Mould on wet surfaces tends to form a dense, clearly defined area. Mould on areas where condensation is forming tends to be spotty and spread out.
It also doesn't take long for any leaks etc to cause the paint to break down and flake. Condensation on the other hand takes a very long time before it causes any damage to the paint.

Corners that are on an outside wall tend to get this as they are the coldest spots in a room so this is where any condensation will occur. Of course there could be a problem behind this that is making it even colder but I highly doubt that there is actual water getting there.

Rorschach · Post by **Rorschach** » Thu Oct 17, 2019 6:48 pm

Also on a related note you say the house is a 50's ex council, is it a BISF steel frame house? Have you had any remedial work done if so?

westcountrycat · Post by **westcountrycat** » Thu Oct 17, 2019 7:09 pm

Hi Rorschach,

No steel in the house or work done. its a solid well built house that's great apart from the mould, i don't think the sloped ceiling helps but i don't get this in the other bedroom which is alongside it, the only difference is the room with no mould has only one external wall.

I wonder if i have two ongoing issues the damp you see in the photo was easy to clean off so i think you are right but i don't know how to make the room any less condensated, the door is always open and its well ventilated and i have windows open at every opportunity. it hasn;t been an issue all spring and summer.

The other wall which is an external wall gets mould along the corner and all the way down, some spots along the skirting and some on the wall particularly along hairline cracks and it looks a more rusty brown colour plus a quite few random spots on the ceiling that side all over browny/black none of it is as clustered as in the photo

Am i dealing with two issues do you think ?

Thanks so much for your help, i feel like i am going round in circles !

Rorschach · Post by **Rorschach** » Thu Oct 17, 2019 7:47 pm

Can you post some pics of the outside of the house, point out where the mould is worst.

How many live in the house, what sources of moisture are there? Regular showers, tumble drier without vent, drying washing inside etc?

Don't be disheartened, it took us several years to pin down our mould issues.

westcountrycat · Post by **westcountrycat** » Fri Oct 18, 2019 10:02 am

Ok here are some pictures

circle marked 1 is were the black clustered mould is that you suggested is condensation.
Circle marked 2 is the wall were there are mould spots all the way down the corner and along the external wall here and also on the ceiling of that side of the room.

The second picture shows the larger room next to it, this suffers from occasional condensation on the window and we find black mould on the bottom of the window sometimes but other than that is absolutely fine.

: Small Room.jpg (62.54 KiB) Viewed 3157 times

: Larger room.jpg (35.41 KiB) Viewed 3157 times

dewaltdisney · Post by **dewaltdisney** » Fri Oct 18, 2019 10:19 am

My first thoughts were house condensation. That does look like spores fed by moisture in the air rather than damp penetration.You need to carry out a forensic check on moisture laden air. The biggest cause is showers, wet towels hanging up, cooking and also how warm the house is all over as having cold rooms and warm rooms can cause problems. Condensation happens on the coldest surface present and I think it is best to leave heating on 24/7 and adjust the thermostat a bit when you go out. The temperature is always warm and and the boiler does not have to work to hard to bring it up a few degrees when needed.

I think that mould spores are present and they have to be killed off as any moisture helps them grow. To give you an idea of how hardy this type of organism is that the diesel bug is a similar type of mould that lives in a diesel fuel tank that has condensation water accumulated over time which the diesel oil then floats on and the bug lives in the interface between the two feeding in hydrocarbons and water.

In the indoor environment the mould spore release is independent of the outdoor environmental conditions and time of year or day. The factors governing the release of spores into the indoor air are all related to human occupancy and activity. If materials contaminated by moulds are disturbed by maintenance activities, cleaning, vacuuming or simply by air current, large quantities of spores can be released in to the air.

I read that not all mould species present in the outdoor environment would find the indoor conditions suitable for growth but some of the mould such as Penicillium, Mucor, Aspergillus, Cladosporium, Alternaria and many others will positively thrive in the indoor environment. Availability of moisture is usually the main factor influencing whether the settled mould spores will germinate and produce unsightly mould growths on walls, fabrics or other materials

DWD