Mould - causes & best treatment ideas

[Peterpiperpickedwrong]

Part of our house seems to be just single brick as it was converted from the old garage.

There was a lot of shrubbery growing against the outside of this wall so we have cleared it wondering if that was causing the dampness.
We have had the brickwork sealed which cost a couple of thousand to have done but we still have Mould coming through.

Is it just from condensation? -warm inside and being single brick construction the wall/internal plaster is cold.

Is it possibly from the drain outside that’s the other side of the wall?

Damp proof course problem?

Who is the best person to call to actually find out what the problem is? I need the solution to be as inexpensive as possible. This house has turned into a money pit!

Some people will tell you, mould killing chemicals, but that's wrong.

The entire world, and the air above it, are full of mould spores.

Why isn't my wall mouldy? Because it isn't damp.

Why is your? Because it is.

You didn't mention which room(s) this is in.

If a kitchen or bathroom, where water functions are performed, you need an effective extractor, and you need to use it.

There is the possibility of a water leak if the room contains a tap, a drain, a pipe, a boiler or a radiator; or if any pipes or drains are in the floor, especially if it is concrete.

If the extension was very badly built, the floor may be damp, depending on its method of construction, and the roof may leak, or the gutters.

Does "one brick" mean four inches thick, or nine?

The one thing that I can be sure will not fix the ventilation or the leak, is a chemical injection into the walls.

post some photos and explain what part of the wall is mouldy.

No possibility of internal water leak- no pipes, rads or boiler or anything on the affected walls. There is a drain outside that wall which I think runs parallel to the wall. Both corners of that wall have mould. Not entirely sure of the wall thickness overall it it just one brick width and then plaster on the inside. The actual wall was built the same time as the house so was quite a quality build in the 50’s but previous owners have just knocked through into what was the garage from the dining room to create an extra sitting room. Concrete floor but this is slightly lower than the outside level -there is a step down from the dining room into this sitting room- the outside is just a concrete & brick terrace there as the ground level slopes/drops quite a bit.

Roof has been checked (we had the gutters replaced so the roofer had a good look)

I just don’t know if we need to call in drainage people, builder, ventilation expert.
Any advice appreciated. Thank you for taking the time to post.

you have quite a severe wet mark along that wall, rising from the skirting, and the highest point is in the corner. Usually the source will be at or near the highest point. I find it hard to think there is not a leak. I do not believe it is condensation or rain penetration.

What is the floor covering?

Please photograph the outside of that wall, including any gullies or downpipes, and indicate where the internal wet patch corresponds.

Please photograph the whole of the two walls shown in that photo, inside and out.

Does the terrace slope towards the house, or away?

Flooring is just the manky carpet that was in when we moved in, don’t want to pay to replace it for it to be ruined again.
DH has, as an emergency measure, filled with extra cement along where the later addition of the patio/terrace wall was added into the brickwork. It is raining now andthe corner of the patio where it is damp inside is completely dry The more red bricks are the terrace wall. No leaks on the cast iron drain pipe. If standing on the floor the top of the terrace wall is well over head height.
Have noticed the bricks behind the drainpipe are looking white below where the internal floor level is.

Hope this all makes sense.

Last pic.

Gotcha!

The wet patch is next to a downpipe and a gulley. There is green algae on the concrete outside, indicating long-term wet. The white marks on the bricks are efflorescence where water has soaked in and evaporated away, leaving the dissolved minerals behind.

In any house in England that was built before 1946, clay gullies like yours are broken and leaking. There might be a house somewhere in the country that doesn't have a broken gulley, but I have never seen it. It needs to be dug out and replaced. The gulley has a U-bend on it or similar kind of trap. The clay pipe it attaches to underground is probably also broken, so needs to be dug out and, at least, inspected. The broken pipe and gulley might be choked with mud or mortar repairs. The result will be that water has been spilling out for around 75 years, so no wonder you have a wet patch. The water might be running along by the wall under the concrete, it's too soon to say, but will become clear when you start digging. Any builder or groundworker can do this kind of job, or you can DIY if you take more advice and don't mind breaking concrete and digging holes. It is tiring but not complicated. Plumbers are weedy little fellows wih petal-soft hands who are not suited to such heavy work. it is essential to use a well-established local persion by personal recommendation, and not to rely on internet searches or advertisements recommendations on websites that the trader pays to be listed.

Depending on local practice, you may have separate drains, or a combined system where rainwater and sewage travel down the same pipes.

If the drain carries water or sewage from more than one house (e.g. if you are at the end of a terrace) then your local water company may have responsibility. You can get a drain company to poke a camera up the pipes from the manholes on either side, but I think I know what they will find, and what needs to be done. It's very common.

The downpipe may also be choked with leaves and grit, so start by cleaning that out. The gulley has a pot that you can scoop out with a ladle. These simple actions might do some good.

Sorry this is not good news.

You are correct in saying that condensation will form on a single brick external wall with the heat of the room hitting the cold plaster. My friend had this causing mould on her wall. The solution was to put up an internal false wall with insulation in it, no problems since and it has made the room much warmer. Something for you to consider?
Looking at your damp, I don’t think this is the cause. It is rising damp. You state that the outside is higher than the internal floor? Surely it is a case of getting a damp proof course. (Just my opinion. Having renovated a house and stumbled across problems, I now realise that most things can be sorted one way or another and they are not to be worried about. Good luck x)

p.s.

I think I can see the DPC in your photo, under the yellow mark "floor here"

The efflorescence rises above this, suggesting the DPC is bridged or damaged, unless water splashes up out of the gulley in heavy rain, as might happen if it is blocked. Examine the joint in the downpipe. These are not (supposed to be) sealed so that in the even of a blockage, water will emerge through the joint above the blockage.

Could water be collecting on the other side of that garden wall? is the earth or paving built up above the DPC?

We had similar in an old house when we moved in. We cleared out drain pipes and guttering which was blocked. We stripped back damp plaster to brick and then had heating on full time. It did dry out. Then we had it re-plastered and then painted with damp proof paint. Also painted clear damp proof coating on outside brickwork. Three years on it has not come back. We think the house was not heated properly before as elderly man lived there alone.

If you're taking any more pics, I'd be interested in the paving or concrete as it runs along the bottom of the wall. Especially any signs of sinking, cracking or repairs and patching, and how far from the drain they are.

And the wall and paving behind that redbrick garden wall.

To pp. When we first moved in we stripped wallpaper, had dehumidifier going, installed new central heating then painted with damp proof paint had the pointing done outside and on the pointing mans advice had a water shield coating put on the outside wall.

PigletJohn The tarmac is in awful condition and there are some sunken bits. Sounds like it will be a case of digging up the outside and sorting drains. The mould is in the other corner of that wall as well and I can see the white goes all the way along the whole of what was the old garage wall. I can see the whole edge of tarmac up to that wall looks really dark/wet. The tarmac changes to concrete where the raised patio was build -this has also sunken over time. Sounds like it is going to be expensive

Can’t reallt take internal without shifting a huge sideboard and other bit of furniture that I can’t do alone.

More

thanks

The relevance of the sunk and cracked concrete, which may have been patched, is that when a drain leaks, the water washes away the soil, so creating a cavity that the concrete subsides into. Sometimes if you hit it, it sounds hollow. Often it has been repeatedly patched.

I see there's another gulley by the wall with the ladder, and the concrete is cracked, so, with the white marks, I will guess the same thing has happened there. Does the concrete slope away from the house, or toward?

i can't see the DPC on the wall by the ladder, can you?

white marks also occur where a washing machine has been draining and the dissolved soap in the water on the bricks leaves traces. Mineral efflorescence is crystals, mostly lime, and very hard, but if you scrape them off and put some in vinegar, will probably fizz. You can't wash them off, as they soak into the bricks and re-emerge when it dries again.

The moss and algae and dark stain are typical of long-term wet.

No other gully. It’s the same one. The tarmac slopes down and then just ends then concrete starts which slopes down to the garden. It doesn’t slope towards the house at all.

The DPC by the ladder in front of the window? Close up we can actually see one but no, we can’t see one on the side wall that has the white (we have a lot of ladders lying around!) You saying about the algae & long term wet makes sense. We obviously need to get someone in to have a look at the drains so we can sort it permanently.

Thanks so much for all the info & for taking the time to post.

@PigletJohn
Just wanted to return and thank you. We didn’t have a clue how to deal with the damp or where to start in figuring out what was causing it. You said.....

clay gullies like yours are broken and leaking. There might be a house somewhere in the country that doesn't have a broken gulley, but I have never seen it. It needs to be dug out and replaced

^you were spot on! Thank you