Mildew all over plywood walls

[Ferdinand]

1 hour ago, Omnibuswoman said:

To be fair, I think the house should be condemned. It’s about to go up for sale, and I think only a fool would buy it. The cottages were built for mine workers by the Duke of Bedford in the 1860s, out of the rubble dug from the nearby mines. A sort of philanthropy on the cheap. 
 

As the doors and windows have been perpetually closed since February, and there’s been no heating on, the whole place has a sheen on mildew - every carpet and wall - and the black mould is even worse than before. It’s an absolute health hazard. 
 

That said, Auntie Rene is still going strong at 94 (now in a care home) having lived in those conditions for over 55 years. Maybe it’s possible to acquire a health benefit from living in such an environment…

 

Plenty of people here will give you free rubble.

[Ferdinand]

1 hour ago, Omnibuswoman said:

Crikey!!!
I’m going to give washing it down and painting with antimicrobial paint a go, but am open to needing to replace it all if that doesn’t work.
 

In the meantime I’m wondering if leaving the front doors open might be a good idea rather than sealing the place up with no heating in situ yet. I’m sure it’s going to get worse. 

 

Don't forget your mask.

 

On your aunt's mugging - that's very sad, as it shows the long term effects of a single traumatic event on one person's life.

Edited October 27, 2021 by Ferdinand

[SteamyTea]

As luck would have it, this week's Book of the Week,  Slime: A Natural History, is being read out on R4.

https://www.bbc.co.uk/sounds/play/m0010wy3

 

Maybe burning is not such a great idea unless done properly. There is an Energy From Waste incinerator near St. Awful. Not far from you.

[Onoff]

19 minutes ago, Ferdinand said:

On your aunt's mugging - that's very sad, as it shows the long term effects of a single traumatic event on one person's life.

 

It was my Mum who got mugged. Cut a long story she was mugged on her way to bingo which she loved by a couple of scumbag opportunists. She gave chase and dived through their open car window to try and get her handbag back. They drove off and she fell into the road. Broke her arm I think it was that time. Never went back to bingo ?

[Omnibuswoman]

3 minutes ago, Ferdinand said:

 

What is the RH level?

 

I might be inclined to close it long enough to dehumidify with one on a long cable, if you can.

I haven’t got a monitor yet, as the building is still open to the elements, and a hygrometer is therefore likely to measure the atmospheric conditions rather than the building per se. 

Inside mum’s cottage the RH is 68%, which mum said is not unusual in wet weather (it’s mizzly outside) even though they have taken multiple steps to try to reduce the humidity. It’s also a damp microclimate down here in the valley.
 

We thought that our place would be drier being at the top edge of the valley, but now I’m not so sure!

[SteamyTea]

15 minutes ago, Omnibuswoman said:

thought that our place would be drier being at the top edge of the valley, but now I’m not so sure!

Depends on altitude as well.

RH is a strange thing that cannot be easily calculated, so approximations are used.

 

Worth making a simple temperature, relative humidity and air pressure logger. They can tell you so much.

Only cost a few quid as well.

[riboid]

Ferdinand - RH is relative humidity.  It is the volume of moisture in the air at any given time and in a %.  100% is saturation, which means you the air cannot hold anymore moisture.

[SteamyTea]

10 minutes ago, riboid said:

100% is saturation, which means you the air cannot hold anymore moisture.

Careful, it is more complicated than that.

The air does not really 'hold' the water. It is the kinetic energy, of all the molecules in the completely fluid mixture that does work on each and every other molecule including the water molecules.

 

Juggling would be a better term than hold, but then that assumes that gravity is the dominant force.

 

 

[riboid]

I use hygrometers on a daily basis: so its the volume of moisture in the air at any given one time.  Simply.  Still a good metric to let you know where issues lie, etc.

[keith65]

I have been putting up plasterboard dot and dab and before I have had a chance to skim, the black mould is forming so have had to put in a dehumidifier running 24/7 I think the warm moist air in the southwest does not help one bit.

[Cpd]

I have not read this whole thread in detail but I HAVE seen this happen.

I have an unheated workshop and I have every type of timber in there, hundreds of bits from OSB to shower board, from mahogany to soft pine and the ONLY thing that goes mouldy is certain types (most types actually) of ply board, NOTHING else goes mouldy. I have seen this happen over the years and now just steer clear of ply. OSB EVERY time now and never a problem. I made the grave mistake of using ply in another shed rather than sarking or OSB and your shed looks exactly as what happened to me, my shed was very well ventilated but it still went mouldy…… I was / am still so frustrated that I went down this route. I treated it with neat thin bleach, sprayed it on with a kitchen spray bottle and it’s been very effective, i wore a full body protection, eye protection and a gas mask with carbon filter. I tried other bleaches - thin bleach from tesco and they did NOTHING !!!!! I have warned a few friends about ply going mouldy and some of then ignored this only to suffer the same fate…… 

https://www.amazon.co.uk/gp/product/B00COM84IM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

this is the stuff I used with great effect, I even bought a few bottles as back up just in case I needed to re- apply but so far so good. 
if your concerned about mould I would rip it out and replace with osb, I am still sitting on the fence about ripping mine as it’s a big cost and a lot of work. 
 

I see the price has gone through the roof since 2019 but I would still recommend this type. 

Edited October 27, 2021 by Cpd

[saveasteading]

I think your idea of ventilated is very different to what the timber industry do. I worked on a few buildings for them and the amount of ventilation is huge. They want a constant draught through the shed.

 

Plywood is particularly vulnerable as the layers are cut from a log as with a pencil sharpener. The surface therefore has the rings spread out and the softer wood is more porous and vulnerable. You can see this on the photos as rings and repeated knots.

 

Seal the wood or create a lot of air movement say I.

[SimonD]

On 25/10/2021 at 20:48, Omnibuswoman said:

All wood exposed to the air was blackened.

 

Have you double checked to make sure this is mildew? I.e. is it slimy/fury and does it sit/grow on top of the wood?

 

I could be wrong but something about the photos makes me think it's more like blue stain, where there is a certain type of fungus that feeds off the sugars in the wood. This does happen when there is excess moisture together with a sugar rich timber, but the difference is that whilst it leaves an ugly surface, the growth dies down naturally once the sugars have been consumed within the wood and or there's a moisture reduction. There isn't typically any damage to the structural integrity of the wood.

 

It would be interesting to know if you've done a moisture test on the plywood itself to know whether it is actually damp?

 

On 25/10/2021 at 22:10, Omnibuswoman said:

ply could absorb and release a certain amount of moisture without any harm coming to it...

 

Yes, it can, but the blackness may not be causing harm to the plywood, just that the wood used in the plywood is susceptible to this kind of growth. It may be that it is a pine based board, like Radiata, or Elliottis as pine. Just a guess...

[saveasteading]

Interesting.  So I found this which seems to back your idea up. You would therefore expect to see this on the sapwood (which are widened by the manufacturing process) and not the strength rings (for which there must be  a word)

 

Blue Stain

Blue stain is a little bit different than the other types of discoloration that we’ve been discussing.  Blue stain is caused by a microscopic fungi that sometimes infects the sapwood of trees and uses it for food.  As the name sounds, the blue stain fungi produce a blue and gray discoloration of the wood, often in the form of spots, streaks, or patches.

It’s also important to note that blue stain does not cause any kind of decay, has no affect on wood strength, isn’t airborne, and isn’t linked to any type of health issues.

[SteamyTea]

59 minutes ago, SimonD said:

could be wrong but something about the photos makes me think it's more like blue stain

Everyday is a learning day.

Is there a test that can be done?

[SimonD]

3 minutes ago, SteamyTea said:

Everyday is a learning day.

Is there a test that can be done?

 

I'm sure there must be, but I'm not familiar with the process. You can see and feel the difference where even though it does cause staining, the black mould sits and grows on top of the wood whereas the blue stain kind of fungus seems to sit within the wood. Difficult describe really, but it also doesn't respond to treatments like oxalic acid which people often claim it does. I've had it happen on glulam beams that got wet and had been treated with a borax preservative solution, for example.

[Omnibuswoman]

Very interesting. 
 

I will have another look tomorrow, but I think it is both! Certainly there is a slight coating of the wood present, and a further type of mould which is a turquoise/green colour which is only on the surface and easy to brush off. The black mould can be brushed off (it is powdery), but seems also to be ingrained - as you describe the blue-stain mould. 

I may see if I can find someone interested in microbiology to have a gander at some samples under a microscope!

[Onoff]

I wonder if it's worth cleaning and painting with a primer containing a biocide? Indeed doing the same for any new wood you fit. Something like this:

 

https://www.zinsseruk.com/product/bulls-eye-1-2-3/

 

Reassuringly expensive btw! 

  

[SteamyTea]

If this blue mould lives off the free sugars in the timber, maybe a blast over with a blow torch, which will combust the sugars, will permanently sort the problem.

See what I did there, I got burning back into the processes.

[Onoff]

14 minutes ago, SteamyTea said:

If this blue mould lives off the free sugars in the timber, maybe a blast over with a blow torch, which will combust the sugars, will permanently sort the problem.

See what I did there, I got burning back into the processes.

 

Aka shou sugi ban! 

[SteamyTea]

33 minutes ago, Onoff said:

shou sugi ban

I shall ask my Geisha Girl.

 

We used to char the saunas before they left the factory.  Never saw any fungi on them.

Edited October 29, 2021 by SteamyTea

[Onoff]

1 hour ago, SteamyTea said:

I shall ask my Geisha Girl.

 

We used to char the saunas before they left the factory.  Never saw any fungi on them.

 

Bet you saw a few fun guys in them though! ?

[Ferdinand]

Charring is an interesting idea.

 

I wonder if it would work?

[SteamyTea]

7 minutes ago, Ferdinand said:

Charring is an interesting idea.

 

I wonder if it would work?

Just need to find an offcut of clean ply, char one side and leave in a shed.

[Omnibuswoman]

11 hours ago, Onoff said:

I wonder if it's worth cleaning and painting with a primer containing a biocide? Indeed doing the same for any new wood you fit. Something like this:

 

https://www.zinsseruk.com/product/bulls-eye-1-2-3/

 

Reassuringly expensive btw! 

  

i bought a tin of zinsser white anti mould paint a couple of days ago, preferring it over the dulux anti mould because it had more sinister health warnings on the back ?