Please help - summerhouse mould problem - is it ruined?

[uptown47]

Hi all,

I'm really hoping someone can help me with this one.

I built a summerhouse last year. The wood wasn't treated at all so, once it was built, my wife (she's head of painting in our house) sprayed it with some Rystix Timbercare stuff. Unfortunately, it was 'clear' and I think she's maybe missed parts, either that or the wood was still wet when she applied it. Either way, one side of the summerhouse has started to get either mouldy or sun bleached?

I think it might be mould but not sure.

I've tried scrubbing it with bleach/water mix but it won't come off. I've also tried lightly sanding it but it won't come off.

I've bought more Rystix treatment, this time in "Oak" hoping the darker colour will help hide the black "mould" (if it is mould?).

Do you think this will work? Or am I just going to cause more problems? Is there a way to solve this?

A big thank you for any help you can give me on this.

Cheers

 

[r896neo]

Looks to me like a poorly applied coating. The mouldy looking areas are where the treatment didn't really take and moisture has got under it.

You need to remove the coating and reapply where needed. that could mean using nitromors or possibly sanding aggessively.

I have seen it happen when people use varnishes on outdoor timber, what was the coating you used?

 

[uptown47]

Looks to me like a poorly applied coating. The mouldy looking areas are where the treatment didn't really take and moisture has got under it.

You need to remove the coating and reapply where needed. that could mean using nitromors or possibly sanding aggessively.

I have seen it happen when people use varnishes on outdoor timber, what was the coating you used?

Thanks for the advice. The coating was called Rystix Timbacare Exterior Wood Sealer and was recommended by the company that I bought the summer house from.

*Edit* It was extremely bad weather when I was building the summerhouse and, although I threw a tarp over it every night, the wood will have been soaking. Also, my wife used a 'sprayer' to apply the Timbacare stuff and, with it being "clear" it is definitely feasible that parts were missed.

I've no idea about mould in wood but it seems really deep in places. Will this mould somehow 'rot' away the wood and leave the summer house like a crumbling old shed? I wondered about just putting the new "oak" coloured sealant over the top of it. The dark colour would help hide the mould but would this spell disaster for the summer house?

Thank you for your help

 

[r896neo]

The mould is a cosmetic issue mainly. You may find the new colour takes a little patchy depending on the type.

 

[uptown47]

The mould is a cosmetic issue mainly. You may find the new colour takes a little patchy depending on the type.

Really?? I wish I'd known that... I've been panicking thinking it would somehow eat away and rot the wood. Jeez, that's great if it's simply a cosmetic issue.

The wood is 40mm thick. I tried to sand it again when I got home last night but the wood is very soft and "furs up" a bit. I think the mould is quite engrained. I've now covered the side I'd tried to sand with a tarp to try and minimise how wet it will get.

I've ordered some Oxalic Acid (Bar Keepers Friend) from Amazon as someone said that is known to remove stains from wood. I'll give that a go when it arrives.

I'm hoping for some baking hot days and then I can apply the oak treatment and I was hoping it would seal the wood to prevent the mould getting oxygen/moisture and prevent it getting any worse.

If it's just cosmetic and not going to eventually rot a big hole in the side of the summer house, or stink the inside of the summer house out with that damp-smell then that's very reassuring.

 

[motorbiking]

Unless you particularly like the soft redwood look, have you thought about a coloured wood stain. They will waterproof the wood as well as having a rot protection.

 

[uptown47]

Yep, the stuff we've now bought is "oak" coloured so a lot darker. Hopefully that will hide/mask the dark patches

 

[r896neo]

Once you have sanded off the treatment oxalic acid is a good choice for removing the mouldness

 

[uptown47]

Once you have sanded off the treatment oxalic acid is a good choice for removing the mouldness

Hopefully, fingers crossed, we get some joy from it. It should be here at the weekend so will have a crack at it then, weather permitting.

Cheers

 

[John D v2.0]

A bit late, but it's not a good idea to try to seal exposed wood. It'll always absorb a little moisture and expand and contract, eventually the seal will fail, and the wood will take on water faster than it can evaporate and then rot.
If you hang a piece of wood from your washing line, it'll never rot. Wrap it in cling film and it'll rot pretty soon.
So you want treatment which soaks in. Nice summer house BTW!

 

[uptown47]

A bit late, but it's not a good idea to try to seal exposed wood. It'll always absorb a little moisture and expand and contract, eventually the seal will fail, and the wood will take on water faster than it can evaporate and then rot.
If you hang a piece of wood from your washing line, it'll never rot. Wrap it in cling film and it'll rot pretty soon.
So you want treatment which soaks in. Nice summer house BTW!

Thanks John for your advice. The Rystix stuff I've got is meant to penetrate the wood as you mix the first coat with White Spirit (turps). I'm going to try the Oxalic Acid first to see if I can remove the staining and then paint the Rystix Timbacare on to it. I've covered the bad area with a tarpaulin this week. There's air getting in but no rain so hopefully it'll be nice and dry when I come to do it. I'm hoping the Oxalic stuff gets here tomorrow as it's meant to be a nice weekend and I might get the job done.

Thanks again for taking the time to answer.