Thread: block wall crack poll

This is a vertical crack in a garage block wall, about 7 feet long/high, and as much as 3/16 inch thick, slightly wider at top than bottom.

Is the crack likely caused by heat expansion from the gas furnace vent, yea or nay?

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In my opinion - Nay

'Twas caused by the hole cut thar, IMHO.

I like the thread title, BTW. It's catchy.

My vote is NO.

What is going on under the wall?

Originally Posted by Steven Turetsky

What is going on under the wall?

I don't know. It's concrete sidewalk along the outside and concrete garage floor on the inside.

Here is the SE's wording:

"The vertical crack in the wall is most likely due to thermal expansion of the wall, particularly at the flue pipe which experiences extreme temperature changes."

I also say no. If it were from the pipe/vent there would be localized cracking around the pipe, including a break in the bond between the stucco and the pipe and some crumbled stucco around it, neither of which there appears to be. In any case I cannot imagine thermal expansion of a pipe causing a 7'-0" long vertical crack in a wall like that. You have not given enough information to give a better opinion, however.

Originally Posted by Thom Huggett

...You have not given enough information to give a better opinion, however.

Twelve year old, three story end-of-row on slab, flat roof, first floor is block, second and third floors are wood frame.
I didn't see any other structural concerns.
I was thinking some kind of settlement problem with footer.

Assuming that we are looking at the flue entering/passing through the wall near the top, and assuming that there is an exterior chimney, then there is no way that thermal expansion has anything to do with this. As said in an above post, you would see radial cracking localized around the flue pipe.

It is almost certainly settlement related (hinging) especially if it is wider at the top than bottom. I'd look at the corners where this wall connects to adjacent walls for any separation or movement.

A Structural Engineer said this? When the flue doesn't even touch the wall for most of the length of the crack? Wow!

I guess that if the flue got to, say, 500 degrees for hours at a time, and.....WAIT.....

NO!