Mould

[FWLR]

Not garden related, but i would like some advice on this please.

After selling this board and all the rest of my N Gauge stuff, save for some locos and wagons and some coaches for when the grandkids come round...

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I found this in the left hand corner at the rear of the shed,

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And this in the right hand corner.

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The help I am wanting please is, can I use PVA watered down a bit to help keep it at bay and not encroach in to the shed, or would I need to buy the stuff that is far more expensive like the damp-prove stuff that I think is not really user friendly. Thinking about myself and the grandkids when they visit.

Any advice would be most welcome.

[bazzer42]

Got to say I would go unfriendly and use one of the cuprinol (or Thompson's?) Product. Something that has rot inhibitor.

[philipy]

First thing to do is identify the source of the dampness that is causing the problem. Until you cure that, anything else is a waste of money. However in answer to your original question, PVA can go mouldy itself, so it won't cure the problem and may make it worse.

[FWLR]

Thanks Philip, I know I think , what the problem is, but it would mean I would have to try and get my big fat belly in between the garage and the neighbours and back garden fence

So the PVA wouldn’t be much use then, I just thought we use it to build for outside, so it may be ok to use for this problem.

[Peter Butler]

The floor (and walls) appear to be made of plywood which will de-laminate if the source of the damp isn't treated first. I fear you will have to squeeze in the limited space you have to fix the problem before you, and your grandkids all fall through the floor!

[invicta280]

I fear you will have to squeeze in the limited space you have to fix the problem before you, and your grandkids all fall through the floor!

or better still, pay someone young and agile to do it. But the advice above is good. Nothing works for long unless you eradicate the source of the damp.

[Soar Valley Light]

Rod,

As others have said, curing the source of the damp is essential. That in itself may be enough to solve the problem but I'd adopt Phil's suggestion and blast it with one of the cuprinol products. Once applied they present a very low health risk. (so long as you don't lick the walls!)

Andrew

[FWLR]

The floor (and walls) appear to be made of plywood which will de-laminate if the source of the damp isn't treated first. I fear you will have to squeeze in the limited space you have to fix the problem before you, and your grandkids all fall through the floor!

Peter, the shed is a proper wooden shiplap, the plywood is just covering the insulation on the walls and the floor is covered with marine ply, so I don’t understand why it has the mould.

Rod,

As others have said, curing the source of the damp is essential. That in itself may be enough to solve the problem but I'd adopt Phil's suggestion and blast it with one of the cuprinol products. Once applied they present a very low health risk. (so long as you don't lick the walls!)

Andrew

Andrew, thanks for your advice, I will be going to get some of the Thompsons stuff, seen it on Amazon for about £15, so for that kind of money it will be going on all the inside of the shed, now that I have room to move since the L shaped Layout has gone.

Won’t be licking the wall either....

Went out to the shed yesterday with son-in-law, he went down the side and said he couldn’t see anything wrong with the side or back of the wooden slats. So it’s a mystery really why the mould is there, I have had an oil filled heater on all winter on a frost setting, so I would have thought it wouldn’t be condensation. Haven’t been in the shed much because it’s been too cold for me to venture out, plus I have been ill.

Hopefully I can get it sorted and all will be well.

[Peter Butler]

Rod, your pictures appear to show damp ingress at the corners of your shed. Although the exterior is a shiplap construction, which is usually good at doing its job, there are joins at the external corners and that looks like the affected parts. Perhaps there are small gaps which could be re-sealed?

[markoteal]

Another issue may be above your head - if water is leaking up high, it may run along timbers to their end (in this case the corners) then gravity takes effect - so the corner outside may be fine but if water is getting in above, it could be accumulating in the corners as it makes it way downward.

Worth another look?

I swear by this stuff for dealing with damp/mould spots (we live in a 170 year old house so occasionally it makes an appearance in certain spots - especially the bathroom when those in th family who like to spend 20 mins in the shower are at home!)

https://www.screwfix.com/p/zinsser-b-i- ... 0wodxO0ECg

Don't think its too toxic (unless you lick it like Andrew highlighted) - needs a couple of coats and its very watery (oddly) so ok when painting lower but a b*gger when you are trying to pain a spot in the top corner) but it does do a job

[Soar Valley Light]

Hi Rod,

Peter and Mark made some good points there.

One other thought strikes me, it's a long shot but could explain 'damp corners'. Do you have any insulation between the outer and inner panelling? With heat on the inside and cold on the outside it's possible to get condensation in the inner space between the two walls. It would most likely form on the back of the inside panelling, where it could run down and pool. Insulation would help but may not be an option now the shed is built. If the problem persists it might help to fit an air vent or two to allow an air flow in the cavity.

It's a lot of work though so I'd definitely try the preservative first!

Andrew

[Peter Butler]

And there's more...... have you thought about rising damp? Is is possible that the shed is standing on material which is transferring moisture from the ground?
Can you see whether there is a membrane underneath the shed between any support blocks?

[FWLR]

Another issue may be above your head - if water is leaking up high, it may run along timbers to their end (in this case the corners) then gravity takes effect - so the corner outside may be fine but if water is getting in above, it could be accumulating in the corners as it makes it way downward.

Worth another look?

I swear by this stuff for dealing with damp/mould spots (we live in a 170 year old house so occasionally it makes an appearance in certain spots - especially the bathroom when those in th family who like to spend 20 mins in the shower are at home!)

https://www.screwfix.com/p/zinsser-b-i- ... 0wodxO0ECg

Don't think its too toxic (unless you lick it like Andrew highlighted) - needs a couple of coats and its very watery (oddly) so ok when painting lower but a b*gger when you are trying to pain a spot in the top corner) but it does do a job

Thanks Mark, just ordered some, getting it tomorrow.

[FWLR]

Hi Rod,

Peter and Mark made some good points there.

One other thought strikes me, it's a long shot but could explain 'damp corners'. Do you have any insulation between the outer and inner panelling? With heat on the inside and cold on the outside it's possible to get condensation in the inner space between the two walls. It would most likely form on the back of the inside panelling, where it could run down and pool. Insulation would help but may not be an option now the shed is built. If the problem persists it might help to fit an air vent or two to allow an air flow in the cavity.

It's a lot of work though so I'd definitely try the preservative first!

Andrew

Thanks Andrew for your advice. I do have insulation between the outside panels and the inside board and I also have the heater on all the time, so it shouldn’t really get any condensation should it. I don’t know really, but there isn’t any at the front of the shed, but then again the double doors are not airtight, if you know what I mean, so maybe there is some air coming from the front, but not the back because it is solid.

[FWLR]

And there's more...... have you thought about rising damp? Is is possible that the shed is standing on material which is transferring moisture from the ground?
Can you see whether there is a membrane underneath the shed between any support blocks?

Hi Peter,

No membrane under, so I am ......... on that point.

[Soar Valley Light]

Hello Rod,

It's sounding like Peter might be on the right track. How close to any wall or fence is the back of the shed. A lack of airflow is the only other possibility I can think of.


Andrew

[FWLR]

Hi Andrew,

The back of the shed is about 10”, so it may well be the problem.

[markoteal]

Re the damp coming up - you can get the DPM (Damp Proof Membrane) that they put into new houses about 2 or 3 courses up from the ground at your local DIY shed - not expensive - either in a roll or pieces - then (and I appreciate you'll need some help with this bit considering your dicky ticker), if you can someone to lift up each corner (ever so slightly) in turn and slide the membrane between the ground and the wooden blocks/rail that form the very bottom of your shed, you will buy yourself a lot more time - this is a cheat I've used when I have inherited sheds before and it does help tremendously.

Obviously ideally you'd move the whole shed and put one big single piece underneath but thats not a go-er here

If you can do this, the damp spots should dry out, especially in the summer (with perhaps some heat applied inside via a fan heater) - once dried out get the Zinc paint on with a few coats - let that dry out and then covert whole area with your preservative of choice.

Job done!

[Peter Butler]

Rod, if you do try to put a membrane underneath your shed you could use a scissor type car jack to give lift without straining back muscles or even involving additional assistance. If space is tight a long bar over a brick can be used as a fulcrum, but that will need help!

[FWLR]

Thanks Mark for your suggestions, that is a great idea, just need to get son-in-laws round now to lift the shed for me while I slide that DPM in. Only thing is the shed is about 2’ away on both sides, so it maybe a bit of a struggle. I will keep you posted on that…