Yet Another Cycling Forum

General Category => The Knowledge => OT Knowledge => Topic started by: Mrs Pingu on 13 February, 2021, 05:21:41 pm

Title: Damp, again (the saga continues)
Post by: Mrs Pingu on 13 February, 2021, 05:21:41 pm: Long term residents may recall my saga of 2016. I'm not going to rake all over it again but...

Back then there was a damp bit in the corner of the building (possibly unrelated to the leaky roof). This is what it looked like mid repair.
(https://live.staticflickr.com/1644/25700523754_11d26d22b9.jpg) (https://flic.kr/p/Fa4Ujw)plaster_01 (https://flic.kr/p/Fa4Ujw) by The Pingus (https://www.flickr.com/photos/the_pingus/), on Flickr

This is what's on the other side of that hole.
(https://live.staticflickr.com/1471/26279463376_8ce00298bf.jpg) (https://flic.kr/p/G3e7U9)IMG_4023_01 (https://flic.kr/p/G3e7U9) by The Pingus (https://www.flickr.com/photos/the_pingus/), on Flickr

You may be able to make it out here between the two satellite dishes.
(https://live.staticflickr.com/65535/50939566621_f8cae68ff4.jpg) (https://flic.kr/p/2kBmAs2)2021-02-13_05-32-31 (https://flic.kr/p/2kBmAs2) by The Pingus (https://www.flickr.com/photos/the_pingus/), on Flickr

Now that plastic vent thingy is not an original feature of the building, and I don't know why it was installed, but I did think at the time of the repairs that it looked like an obvious place for water to get blown in. I seem to remember plonking a big rock behind it on the basis that it was handy and hoping to deflect the worst of any rain.

Anyhoo, as far as I could tell it was fine for the next few years, but towards the end of last summer I noticed it was getting mouldy down there again, and of course it's only getting worse now. It doesn't look like there's water coming in from above. It's not humid in the room - no condensation on the windows of a morning and the RH meter (situated about 2 meters away on the other side of the room) says about 40-50% which is pretty good for this time of year.
I need to do something about this, but as I'm hoping we might be able to sell this place to some other mug this year I don't want to get sucked into any major wall/plaster ripping down based type 2 fun.

I'm thinking I just need to find a way to stop water getting into the vent. Of course if it was installed horizontally then I could just fit a vent cowl over it, but it's not, so I can't.
I was thinking about asking my slate replacement operative to come round and slap some cement over it. I don't think I need to be over concerned about ventilation in the wall as when I'm upstairs in the loft it feels like there's plenty down that wall.

Think I might get away with that and some dehumidifying and antifungal wash inside?
Title: Re: Damp, again (the saga continues)
Post by: Mr Larrington on 13 February, 2021, 06:25:56 pm: Expanding-foam-inna-can?
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 13 February, 2021, 06:47:48 pm: Mmm possibly. Don't think I'm going up there on a ladder tho.
Title: Re: Damp, again (the saga continues)
Post by: Kim on 13 February, 2021, 07:00:19 pm: Shirley there must be such a thing as a cowl that would cover the vertical height of that vent, even if it would have a lot of unused horizontality?
Title: Re: Damp, again (the saga continues)
Post by: Mr Larrington on 13 February, 2021, 07:25:09 pm: Quote from: Mrs Pingu on 13 February, 2021, 06:47:48 pm
Mmm possibly. Don't think I'm going up there on a ladder tho.

Isn’t that what Pingus are for ;)
Title: Re: Damp, again (the saga continues)
Post by: De Sisti on 13 February, 2021, 08:08:12 pm: Quote from: Mr Larrington on 13 February, 2021, 06:25:56 pm
Expanding-foam-inna-can?
Just what I need. Thanks for the top-tip. :thumbsup:
Title: Re: Damp, again (the saga continues)
Post by: Gattopardo on 13 February, 2021, 08:40:12 pm: Wrong kind of vent, should have an air brick. The vent should have a mesh behind it and a louvred vent.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 13 February, 2021, 08:41:57 pm: Yes I know it's shit but it's there now.
Title: Re: Damp, again (the saga continues)
Post by: Gattopardo on 13 February, 2021, 08:45:52 pm: Quote from: Mrs Pingu on 13 February, 2021, 08:41:57 pm
Yes I know it's shit but it's there now.

Sorry, can you get up a ladder and replace it?

Thinking if you could put some fine mesh behind the vent so the water can be caught and drain safely.

MODIFY: Actually no more nails stick a louvred vent on that one. https://www.toolstation.com/louvre-vent-flyscreen/p54697
Title: Re: Damp, again (the saga continues)
Post by: De Sisti on 14 February, 2021, 08:39:06 am: Quote from: Gattopardo on 13 February, 2021, 08:45:52 pm
Quote from: Mrs Pingu on 13 February, 2021, 08:41:57 pm
Yes I know it's shit but it's there now.

Sorry, can you get up a ladder and replace it?

Thinking if you could put some fine mesh behind the vent so the water can be caught and drain safely.

MODIFY: Actually no more nails stick a louvred vent on that one. https://www.toolstation.com/louvre-vuoent-flyscreen/p54697 (https://www.toolstation.com/louvre-vent-flyscreen/p54697)
If you can't get hold of No More Nails, there are alternatives.
(click to show/hide)
(https://media.screwfix.com/is/image//ae235?src=ae235/22070_P&$prodImageMedium$)
Title: Re: Damp, again (the saga continues)
Post by: Pingu on 14 February, 2021, 05:38:24 pm: Quote from: Mr Larrington on 13 February, 2021, 07:25:09 pm
Quote from: Mrs Pingu on 13 February, 2021, 06:47:48 pm
Mmm possibly. Don't think I'm going up there on a ladder tho.

Isn’t that what Pingus are for ;)

Oi! :demon:
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 14 February, 2021, 05:45:38 pm: I don't think our ladder will reach, you're ok ;)
Title: Re: Damp, again (the saga continues)
Post by: Kim on 14 February, 2021, 05:48:13 pm: l+1 :thumbsup:
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 14 February, 2021, 05:57:23 pm: This is where a jetpack would come in handy.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 06:51:56 pm: Sorry, I was just getting off about your lath again.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 06:55:07 pm: Anyways..... Cold bridging innit, mould loves it.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 16 February, 2021, 06:58:17 pm: Quote from: Aunt Maud on 16 February, 2021, 06:55:07 pm
Anyways..... Cold bridging innit.
Hmm?
I don't understand why it's just got like this in the last 6 months.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 07:01:34 pm: Jet O' Cold air against the back of a thin, warm plaster wall and hey presto it goes black and mouldy.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 07:02:44 pm: New double glazing ?

Plus it takes a bit of time for the moisture level in the plaster to get high enough for mould spores to germinate.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 07:21:33 pm: Still air can do it too. Have you put anything in front of it in the last year ?
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 16 February, 2021, 07:24:14 pm: Quote from: Aunt Maud on 16 February, 2021, 07:02:44 pm
New double glazing ?

Not sure how that would help?
This place recommends adding insulation inside but I'm unconvinced. Do you not just end up with a load of hidden damp and mouldy bits instead? http://www.underoneroof.scot/articles/1573/Energy_Efficiency_Improvements/Insulating_traditional_solid_walls

There is a hifi stand (open) in front of it but it's always been there.
Title: Re: Damp, again (the saga continues)
Post by: ian on 16 February, 2021, 07:38:20 pm: Isn't the wall getting cold and causing moisture to condense out of the air onto the exposed surface (and not a warm wall)?

You shouldn't take advice from me for all manner of reasons that should be obvious, but if there's no cold interior surface to the wall, then ambient moisture can't condense on it. But it has to be properly sealed, otherwise yes, it'll just condense on the cold surface behind it.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 07:41:39 pm: That's it, it condenses on the inside / room surface at the moment.

I meant if you had had new double glazing installed, as that can lead to more moisture in the room. It only takes a bit more humidity for mould to get going.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 16 February, 2021, 08:22:25 pm: Ah ok. No, the DG hasn't been replaced. It has no trickle vents but then it never has.
No moisture builds up on the window in there, which suggests the wall is colder than the window...
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 16 February, 2021, 08:30:40 pm: You could try covering up the vent, but that cavity needs to be vented as that's what the design relies on.

Can you not install a panel radiator on that wall to heat the wall and cover up the mould. That's what I'd do.
Title: Re: Damp, again (the saga continues)
Post by: valkyrie on 16 February, 2021, 08:34:31 pm: It looks to me like that opening was originally made for a pipe. Maybe an old boiler flue or drainpipe connection? Whatever it was for, it’s clearly just a cold bridge now. I’d bit the bullet and pay for a man with a ladder to remove the vent, fill the hole with expanding foam and then brick it up. If fitting a stone or brick to close the hole is tricky then you could use something like a soot door cover instead.
Title: Re: Damp, again (the saga continues)
Post by: ian on 16 February, 2021, 08:40:44 pm: We had a proper damp surveyor for this place (we pulled out the kitchen, and groo) and that was down to cold walls, moisture, limited airflow around the back of appliances, and the fact the dishwasher had been leaking slowly like an old, drunk uncle into the corner for years. Once we'd cleaned up after the incontinent dishwasher (or rather paid someone to do it), he recommended tiling the walls behind the units (so moisture can't soak in), making sure there was space for airflow, and keeping the kitchen warm.

Basically, any significant temperature gradient will condense ambient moisture, but mould requires permanent moisture ~75% or higher – so a surface that is wet more than it is dry.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 16 February, 2021, 08:55:03 pm: Quote from: Aunt Maud on 16 February, 2021, 08:30:40 pm

Can you not install a panel radiator on that wall to heat the wall and cover up the mould. That's what I'd do.
Hmm, could do I suppose. If we haven't managed to offload this place before autumn (which I have an unhappy suspicion may transpire) maybe I'll give my plumber a shout.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 17 February, 2021, 07:13:45 am: Quote from: ian on 16 February, 2021, 08:40:44 pm

Basically, any significant temperature gradient will condense ambient moisture, but mould requires permanent moisture ~75% or higher – so a surface that is wet more than it is dry.

I'd be surprised if it's rain doing it, as it needs to get through the vent, along the tunnel and hit the wall. Unless there's a puddle forming, but then the carpet would be wet.

You could close most of the vent up and live a smaller hole for the air to get in.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 17 February, 2021, 12:37:23 pm: Ok, if I was to squirt a load of expanding foam in there but leave a wee slot at the top would that not still leave me with the same cold bridging issue?

I take it when you said put a panel radiator on the wall you meant a GCH one, not an electric?
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 17 February, 2021, 04:39:43 pm: Something like that.

Any radiator would do, but if you've got gas and its cheaper then that would be the one I would use.

The radiator would heat the wall and dry it out, plus create convection currents and increase the airflow over that part of the wall. Mould loves still air, which is why it's first found in corners of ceilings or at the bottom of walls behind furniture.

In the meantime, you could wipe it off with a cloth to reduce the number of fruiting bodies which produce spores. Just wipe it off with a dry paper towel and keep at it on a regular basis. It should keep it at bay for the meantime.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 17 February, 2021, 05:00:55 pm: Cool. I've got some fungicidal stuff (Granocryl) coming this weekend which will help a bit, hopefully, and I've spied somewhere that will hire and deliver a decent ladder so that can be a job when I'm off in a couple of weeks. In the meantime I just need to persuade Pingu to move the hifi stand a bit so I can get in at the wall...
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 17 February, 2021, 05:15:21 pm: It's a horrid thing.

We had it in our place in Somerset after I installed double glazing. It went ballistic and the only way I could get rid of it was to sell it to someone else with the house still attached.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 17 February, 2021, 05:40:51 pm: Aw don't tell me that.
Title: Re: Damp, again (the saga continues)
Post by: ian on 17 February, 2021, 05:46:36 pm: Give it a good wipe down with a fungicide (benzalkonium chloride or similar).
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 17 February, 2021, 06:12:56 pm: That's what's in that Granocryl stuff.
Title: Re: Damp, again (the saga continues)
Post by: hbunnet on 17 February, 2021, 10:03:18 pm: I hope this helps.

We live 10 miles S of PHD and this has been the wettest winter we remember in 40+ years. So not so different in ABZ.

A flat roof leak I thought I had cured 20 years ago has reappeared although it seems OK now with (at last) improving weather.

Your problem could just be the weather, which is my excuse for doing nothing.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 18 February, 2021, 01:12:50 pm: Benzalkonium chloride is toxic to cats, mind.
Title: Re: Damp, again (the saga continues)
Post by: ian on 18 February, 2021, 03:37:33 pm: Everything is toxic to cats. Even mild criticism. Fortunately, they don't often lick walls unless you treat them with tuna first.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 18 February, 2021, 05:13:00 pm: Yes. Benzalkonium chloride is probably toxic to everything too. I shall endeavour only to make up a small amount in the hope I remember not to pour it down the drain afterwards...
Title: Re: Damp, again (the saga continues)
Post by: hellymedic on 18 February, 2021, 06:19:34 pm: That might be an over-reaction, given how commonplace benzalkonium is in Dettol, hand sanitiser and zillions of other cleaning products.
Title: Re: Damp, again (the saga continues)
Post by: ian on 18 February, 2021, 06:26:01 pm: It's relatively common in medical preservatives, though they seem to be phasing it out, probably because they can rely on sterilization and hyperfiltration. It has also disappeared, much to my annoyance, from the Waitrose Daily Shower Shine.
Title: Re: Damp, again (the saga continues)
Post by: Aunt Maud on 19 February, 2021, 07:10:39 am: You may see it as a mild over reaction HM, but it's still a truefact™ and worth being aware of.
Title: Re: Damp, again (the saga continues)
Post by: djmc on 19 February, 2021, 07:28:54 am: Here in France they recommand spirit vinegar to remove mould from walls rather than bleach. You can buy it for such in DIY and hypermachés on the hardware/cleaning departments.
Title: Re: Damp, again (the saga continues)
Post by: ian on 19 February, 2021, 09:53:33 am: Killing mould is quite difficult, the spores are Hard to Kill without stathaming them with proper chemicals. They will laugh at vinegar and, quite possibly, the French.

Any damp surface will get re-infected, mould spores are environmentally ubiquitous, you're breathing them in with every breath.

So basically, however you kill what's currently on the surface, if it stays damp it will be reinfected.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 19 February, 2021, 12:36:30 pm: Quote from: djmc on 19 February, 2021, 07:28:54 am
Here in France they recommand spirit vinegar to remove mould from walls rather than bleach. You can buy it for such in DIY and hypermachés on the hardware/cleaning departments.
I had seen that. What I read was that it actually kills it, as opposed to bleach which just makes the black go away....
Title: Re: Damp, again (the saga continues)
Post by: hellymedic on 19 February, 2021, 02:43:26 pm: I used copper sulphate from a sibling's chemistry set to kill mould on my Pedersen saddle.
Seemed to do the trick.
Moulds don't like Cu⁺⁺!
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 19 February, 2021, 03:59:50 pm: Of course my lovely lime plaster probably won't appreciate me dissolving it with acetic acid. Anyway the Granocryl has arrived.
Title: Re: Damp, again (the saga continues)
Post by: ian on 19 February, 2021, 04:30:35 pm: Basically, you won't kill mould spores as they're chitinized little motherfuckers, and if you did, more would simply land there. So basically it's a case of removing the conditions for them to germinate (removing the moisture) or putting something there that prevents germination or kills them if they do. The only full-time solution is the former, wet surfaces will always eventually turn mouldy.
Title: Re: Damp, again (the saga continues)
Post by: Moleman76 on 20 February, 2021, 07:18:24 am: Regarding lime plaster, do note that if the surface is appropriately base (I think pH > 11 or so), mold (mould) can't propagate. There are some "lime paint" products (at least over in USAnia) that do their mold-proofing work on that basis.
Bleach just takes the black away. Does not kill the stuff.
Reducing humidity is another solution, as is making sure there is no cellulose about.
Title: Re: Damp, again (the saga continues)
Post by: Mrs Pingu on 22 February, 2021, 06:47:37 pm: I've just been pointing my ~~speed gun~~ IR thermometer at all the walls (just for the giggles) and that little section there is definitely the coldest. There's about 4°C difference between the bottom and the top of the alcove and the bottom bit is significantly cooler than the rest of the room. Even the dormer cheeks weren't very cold, which surprised me.