Pressure-treated wood

[kristiina]

We bought pressure-treated wood for a 35 sqm deck. It was laid in June. Now it is completely spotted with black mold. It is on the south-facing side and worst under the roof. Is this something that is normal? The store claims it is when we complained.

 

[Leif i Skåne]

Have you oiled it with a wood oil like linseed oil?
This tends to turn black.
Take a photo and post it here.
Check here post #6
https://www.byggahus.se/forum/threa...irke-sprucken-obehandlad.277627/#post-2738205

 

[kristiina]

Have you oiled the wood with wood oil like linseed oil?
This has a tendency to turn black.
Take a photo and upload it here.
Check post #6 here
[link]

No, we haven't treated it with anything. Planned to wait a year with this.

 

[Rickard.]

My best guess is that you have some sort of plant or tree that releases something that falls on the deck, which then causes that. Whatever it is, it needs nutrients and I don't think it finds that in the deck.

 

[kristiina]

My best guess is that you have some sort of plant or tree that drops something that settles on the decking and then causes that. Regardless of what it is, it needs nutrients, and I don't think it finds that in the decking.

So we've replaced the wood, had pressure-treated lumber for 15 years without mold. No plants nearby.. The deck and the lawn are separated by a path in between.

 

[Tjrex]

Does it come back after you wash it off?
It's normal with some regrowth but that looks worse...

 

[Boende45]

There should be something in the air that nourishes the mold, i.e., some vegetation or emissions in the air.

My terrace, which was laid last summer, is completely free from growth, however, I get stains from the neighbor's leaves. It is also untreated.

 

[ArneTW]

No one has been grinding with an angle grinder or cutting metal, etc.?

Iron particles can form and look like that...

/ATW

 

[skaraborgsfakir]

No one has ground with an angle grinder or cut metal, etc.?

Iron particles can end up and look like that...

/ATW

I myself was thinking about soot.

 

[ArneTW]

https://www.byggahus.se/forum/threads/ny-altan-svarta-prickar.383087/

Welded?

/ATW