ᐅ Issue with rafters / eaves from the outside – Mold or algae?

Hello everyone,

We have now been living in our private home for over six months.
Recently, we noticed an issue with one of the rafters under the roof overhang on the outside (garage).

See the pictures.

All the other rafters are fine.

What could this be?

All rafters were painted three times with wood preservative.

Thanks and best regards

Algae, lichens. Apply Schuruco Moosweg on it and wait 24 hours, then dust off.

Here is the opinion of my architect:

That looks like mold.

It’s likely that the wood came into contact with contaminated moisture from the ground. This can happen during storage. Alternatively, the carpenter may have simply used a bad piece of wood that was already infected.

First, treat it with an anti-mold agent from the hardware store to prevent it from spreading further. When the weather gets warmer outside, sand the affected rafter until the mold is gone, then apply a generous coat of anti-mold primer. After that, just paint over it with topcoat paint. That should take care of it.


What do you think?

If there is mold, then it’s roughly as he describes.
Chlorine helps against mold, so spray a diluted solution of Dan Klorix with water at a ratio of one to five.
For algae and lichens, salt-based compounds are effective; shuruco moosweg is the product commonly used by landscape gardeners and cemetery caretakers. Both options are affordable. Karsten