Wood suitable for loft

[greenhouse24]

I'm doing some fairly minor work in my loft, adding some solid insulation boards in a poorly insulated area. I want to run 50mm wood at right angles across the existing beams, to allow a double thickness of solid insulation with loft boards on top.

I have some pretty cheap untreated wood from a local timber supplier, but looking at it it seems possibly to have mould on it (picture attached). Can anyone more knowledgeable than me explain if it is mould or something else, and if the wood is suitable for me to use in the loft.

Thanks

 

[Harry Bloomfield]

Which particular wood in your photo, are you concerned about - there appear to be three different ones there, but all look fine.

 

[greenhouse24]

Which particular wood in your photo, are you concerned about - there appear to be three different ones there, but all look fine.

The piece along the horizontal centre of the photo, with a know in the side and on top.

 

[Harry Bloomfield]

The piece along the horizontal centre of the photo, with a know in the side and on top.

know = knot I guess - Yes it looks fine, the dark colour maybe suggest it is treated timber.

 

[Deleted member 174758]

Fairly normal - just indicates it's been stored in dampish conditions at some point. Nothing to worry about IMHO