Have built a guest cottage and house during the year and have discovered that some boards have developed mold growth to the extent that the wood has blued. The roofs are low-pitched, ventilated, and covered with underlay felt + SBS waterproofing of the latest model. No leakage occurred before the waterproofing was applied.
It looks a bit strange as one board can be affected while the one next to it is white as snow. I'm wondering if certain boards in a batch could have a greater susceptibility to moisture than others, reaching the moisture threshold for fungal growth while others remain below it. The growth is also limited on the affected boards in some places, so that completely unaffected round rings of about 5-6 cm in diameter have formed. The strange thing is that the boundary between the fungus and the unaffected part is absolutely razor-sharp.
Has anyone else had similar experiences?
It looks a bit strange as one board can be affected while the one next to it is white as snow. I'm wondering if certain boards in a batch could have a greater susceptibility to moisture than others, reaching the moisture threshold for fungal growth while others remain below it. The growth is also limited on the affected boards in some places, so that completely unaffected round rings of about 5-6 cm in diameter have formed. The strange thing is that the boundary between the fungus and the unaffected part is absolutely razor-sharp.
Has anyone else had similar experiences?
Sure enough, as you write, there is a difference between the boards, some sawn from sapwood and some from the heartwood... and in some, you see the boundary between sapwood and heartwood, as sapwood has a much greater tendency to become blue than the heartwood.
The heartwood is larger at the root end, so it generally contains a larger portion of the heartwood than the top end of the board does, which is why the boundary you see often should run slightly diagonally across the board... but it depends on how the log is sawn.
Aren't the round bark-free rings former branches where it is significantly "fattier"?
The heartwood is larger at the root end, so it generally contains a larger portion of the heartwood than the top end of the board does, which is why the boundary you see often should run slightly diagonally across the board... but it depends on how the log is sawn.
Aren't the round bark-free rings former branches where it is significantly "fattier"?
Check how your ventilation is doing in the attic. How is the heat inside the house, as well as the vapor barrier? If you don't have a vapor barrier but the heat is on inside, you'll get moist air in the form of steam rising to the attic. There, the moist air meets your cold plywood and condensation occurs. If you have a vapor barrier, you might have too little insulation in the attic. Then you heat up the outdoor air, which increases the relative humidity in the attic, which in turn condenses against the cold plywood. Too much ventilation in the attic can also cause problems. Difficult questions that you may need to consult with an expert about. Munters or Anticimex might be available in your area. Tartan
I got exactly like you.
The explanation I've received is as it was written above, namely that there is different quality of timber in different parts of the board.
And that it has to do with how dry the timber was when it was nailed up.
I see very clear unstained parts where the ströläkten was placed, i.e. a 5cm wide band across the board.
/Thrax
The explanation I've received is as it was written above, namely that there is different quality of timber in different parts of the board.
And that it has to do with how dry the timber was when it was nailed up.
I see very clear unstained parts where the ströläkten was placed, i.e. a 5cm wide band across the board.
/Thrax
When I built trusses for my shed, some of the beams had been lying on the lawn for a few hours during the construction phase. These were the only boards that developed blue mold after a couple of weeks. The other boards around them were and still are completely undamaged.
The grass probably provides a lot of nutrients for the mold...
/Herman
The grass probably provides a lot of nutrients for the mold...
/Herman
It was apparently very common, my carpenter also confirmed that the råpont has worsened in recent years and that mold growth has increased.
Haagbard; it is true as you write that the mold growth stretches diagonally along the board.
Thrax; it is probably as you say that the ströläkt has created the clean spots since they are symmetrically along the board. Strange it looks anyway.
Haagbard; it is true as you write that the mold growth stretches diagonally along the board.
Thrax; it is probably as you say that the ströläkt has created the clean spots since they are symmetrically along the board. Strange it looks anyway.
The picture by wilson_1 seems to be taken at my little construction site! 
I've bought most of my timber from the same lumber yard and regardless of what I've bought, mold has almost always appeared somewhere on the wood.
Just like thrax writes, I also have unaffected areas that match, within a couple of millimeters, where the straps and battens were on the boards when they were stored at the lumber yard.
My own theory about this is that the wood gets "infected" already at the lumber yard and that the mold then blooms when you nail up the boards and they are exposed to the weather elements. Or rather the humid autumn we've had outside Strängnäs...
The tip I received was to attack the mold with undiluted bleach. Which I have done with a regular scrub brush. Where I've done this, the mold hasn't come back (except in spots where I cheated and didn't scrub enough )
I've bought most of my timber from the same lumber yard and regardless of what I've bought, mold has almost always appeared somewhere on the wood.
Just like thrax writes, I also have unaffected areas that match, within a couple of millimeters, where the straps and battens were on the boards when they were stored at the lumber yard.
My own theory about this is that the wood gets "infected" already at the lumber yard and that the mold then blooms when you nail up the boards and they are exposed to the weather elements. Or rather the humid autumn we've had outside Strängnäs...
The tip I received was to attack the mold with undiluted bleach. Which I have done with a regular scrub brush. Where I've done this, the mold hasn't come back (except in spots where I cheated and didn't scrub enough
)The picture could also have been taken at our house. The same phenomenon is also found outdoors - the eaves.
Does it really need to be removed, or? Can it become more?
It must have come from the building supplies store. Old planks from the 1960s at our place should otherwise have been affected too.
Does it really need to be removed, or? Can it become more?
It must have come from the building supplies store. Old planks from the 1960s at our place should otherwise have been affected too.
Member
· Västra Götaland
· 219 posts
Hello
I believe the wood molds because it isn't properly dry when we purchase it.
There is too much haste in getting the timber out for sale. The theory that it gets "infected" at the lumberyard is probably not entirely wrong. In many places, there are shavings and other things that retain moisture everywhere. Perfect conditions for growth.
If you use Boracol, which is liquid, on the timber. It kills the microbial, mold/bacteria, etc. It is supposed to have an effect for up to 5 years.
Just don't spill it in nature. Aquatic animals die immediately.
Mats
I believe the wood molds because it isn't properly dry when we purchase it.
There is too much haste in getting the timber out for sale. The theory that it gets "infected" at the lumberyard is probably not entirely wrong. In many places, there are shavings and other things that retain moisture everywhere. Perfect conditions for growth.
If you use Boracol, which is liquid, on the timber. It kills the microbial, mold/bacteria, etc. It is supposed to have an effect for up to 5 years.
Just don't spill it in nature. Aquatic animals die immediately.
Mats
I have the same experience.steffen said:
See pictures in the thread http://www.byggahus.se/forum/smahus-garage-friggebod-m-m/227463-garage-svartmogel.html