Stains on masonry blocks.

2000 built Colonial with a partial finished basement.

Vinyl siding no brick veneer.

Stains observed on only one wall adjacent a concrete porch slab.

Stains on top third of block. 20% moisture noted with a meter.

What do you think caused the stains?

No downspouts in vicinity.

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Did you check level of the slab? Sloped towards or away from the home?

The porch looked great. No cracks, sloped away. And it faced east. Most weather around here comes from the west, north and south unless we get a Northeaster.

Just seemed a strange place for moisture and it was not the typical coloration of stain.

David, I have seen familiar stains like that on block before.

Since I can’t see the whole picture of conditions, I am only guessing.

Those appear to be stains created by wet plywood, OSB, regular lumber etc., leaching through the block work and creating that dirty rusty water stain. Water and/or moisture is negating the Building Envelope in that area somehow.

Hope this helps. :):smiley: