Marks on basement walls - cause???

[Terence McCann]

Hello all:

Have a look at attached picture.

What would cause these marks on the basement walls?

It looks like when you shoot something with a BB gun, how it is deep in the center and fans out towards the edges. These marks were on all walls.

Each one of these had water stains and looked rusty as well .

TIA

Download Attachment: Bradley.jpg

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[Jim Katen]

Originally posted by Terence McCann

. . .

What would cause these marks on the basement walls?

It looks like when you shoot something with a BB gun, how it is deep in the center and fans out towards the edges. These marks were on all walls.

Each one of these had water stains and looked rusty as well . . .

From your description it sounds like the cone-shaped depressions left in concrete from snap-ties.

- Jim Katen, Oregon

[Garcha]

I'll bet Jim is right.

[kurt]

Ditto on the Katen. If they're in any recognizable pattern & height, they gotta be snap tie holes.

[Terence McCann]

When you guys talk about snap ties are you referring to the type you see on poured concrete foundations? If so that's not what these marks are (at least I don't think so)

I have to go back today to p/up the Radon monitor, perhaps I'll take a closeup.

TIA

[Chad Fabry]

Here's my guess and I'm glad that I didn't jump on the snap tie theory since it's a block wall.

theory 1) hydraulic cement was used to patch imperfections. The iron oxide in hydraulic cement is the element that causes it to expand as it cures from the rusting and resulting expansion. The water proofing varieties of hydraulic cement don't have a ton of iron in them, but machinery grade (they bore holes in a floor then set the bolts that hold the machines down in hydraulic cement in the floor) has a LOT of iron content and will literally rust. That's the least plausible of the two theories given the locations of the pops.

theory two) the local aggregates used in the manufacturing of the block was high iron ore content and that caused the rust, the expansion and the 'pop'. There are'nt any apparent problems in the mortar joints. Slightly more plausible theory.

[Darren]

I would go with something along the lines of Chads theory #2; Something in the block manifacturing process.

Darren

www.aboutthehouseinspections.com

[Terence McCann]

I like two as well.

[chrisprickett]

That's my guess, #2. The fact that there are no rust spots in the mortat joints, leads me to rule out something done by a homeowner (b-b gun, trying to secure something to the wall, etc)

[kurt]

I said snap tie because on the original post, there was no photo. Plus, Katen said it first; it's dangerous to disagree w/ Katen.

[Les]

Chad's theory number two is likely right. Not an uncommon thing in 40+- year old walls. Kinda regional in concrete block. I think he is a little shakey on theory number one.