Thread: Commercial CMU Wall Cracking

Generalized cracking along and across mortor joints in Alaska

This CMU constructed warehouse in Anchorage is 50' by 50' by 24' high built in 1983 using conventional 8" by 8" by 16" block. Rebar spacing is unknown but is assumed to have met 1976 or 1980 UBC. There are no mezzanines, pilasters or any other interior columns and full span Steel Bar type Trusses are assumed to stand about 48 inches in height; subtracting the interior ceiling drywall height from the outside roof to ground height, with no access to the truss space.

The two types of cracking are:

1) Generalized cracking both along and across the mortor joints over the entire long south facing wall; with a curious more pronouced cracking pattern of an approximately 8' by 10' grid seemingly super imposed upon the generalized joint cracking.

2) Moisture intrusion freeze cracking along the unprotected & un caped parapets and wing wall extensions.

The slab and support structure/footings appear to be stable; in that no differential movement/displacement is appereant.

My hunch is that the large wall area, without pilasters or other architectural reinforcement; has been subjected to so much Seismic stress over the decades, that the motor joints have largely failed, leaving the Rebar to hold the wall together.

I guess the main questions are-

Can the wall continue to hold up and do it's job into the future, as it has done in the past?

Will the appearence be a Deal Killer in the present or future that could come back on me?

Should I refrain from offering conclusions and just punt the whole issue over to an Engineer for a formal analysis?

I'd appreciate your thoughts on this inspection that I promised to complete by Tuesday 12/14.

Thanks

Kris Ericsen ICBO ICC
Anchorage AK

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Originally Posted by Kris Ericsen

I guess the main questions are-

Can the wall continue to hold up and do it's job into the future, as it has done in the past?

Probably, and probably for some time to come too.

Will the appearence be a Deal Killer in the present or future that could come back on me?

Definitely could be, how can one predict the future and what a future buyer and future inspector will be looking at and for, especially given that an inspector's knowledge is expected to continually grow over the years.

Should I refrain from offering conclusions and just punt the whole issue over to an Engineer for a formal analysis?

That would be my course of action, after stating what I saw and what I thought about what I saw - let the engineer quiet the grumblings over what I saw, or, possibly point out that they are worse than I suspected - but the engineer is the one who would sign and seal a letter stating all was well if they think all is well.[/quote]

Looks to me like there was some construction technique used which has caused a horizontal pattern difference every 6th course of block, and a vertical something (not normal expansion/contraction joint) at inconsistent intervals.

Those freeze/thaw cracks could lead to: a) leakage into the interior; b) those loose ends of the concrete blocks falling off and causing damage (or injury or death).

Just what I see in that wall.

Could that horizontal crack be along a bond beam course?

How about an infrared scan of the wall?
BlockWallScanIR™ - Block Wall Construction Scanning

Kris,

In your third picture there is what appears to be rust staining on the wall. Without the proper coping on the parapet I wonder just how much water is entering the wall and what it's doing to the rebar. You could speculate with the client as to what may be going on but I wouldn't put that in writing. I'd point out only what you see and defer the condition to a qualified contractor. It's his job to figure out what's going on.

Kris, I have built a lot of these buildings over the years mainly on Vancouver Island which is in a similar seismic zone. Structural wise it appears to have bond beams
every 4 feet horizontal which is a good thing can't tell on the vertical spacing without tapping on the wall . Also can't tell by the pics if those are full height vertical
cracks or built in control joints. If they did not build it with C.J.'s that would explain a
lot of the cracking.Good news is that the reinforcing is going to hold it together. What
might be of more interest is the truss to block connection the seismic codes for that have changed since it was built. If you are getting an engineer there I would think that would be a very important thing to check. Hope some of this helps. Evan.......

Originally Posted by Evan Wray

Structural wise it appears to have bond beams
every 4 feet horizontal which is a good thing .......

Every 4 feet? That's sounds like a lot of bond beam.

I figured the vertical were control joints, But then thinking about that, he said there was pilasters or interior columns. If thats the case, whats supporting the wall at the CJ's?

There would be a vertical reinforced cell on each side of any C.J.'s with 50% of the horizontal reinforcing running thru. Without pilasters the engineer may have went with 3/4 " rebar at a closer spacing prehaps 32" O.C. depends on the engineer. The rust is more likely to be a peice of wire ladder reinforcing in the mortar joint to close to the surface or something driven into the wall. The parapet flashing should definitely go up and over the top of the wall. Some maintenance is overdue.


Evan Wray
Mason and internachi member

Darn it looks cold there. No inspections today so i played golf in shorts

Yes it is cold here in Edmonton also very jealous of the golfing in shorts.Will be doing the same when we go to our place in Casa Grande in january, how's business in Tucson?

Evan Wray

Mason and Internachi member

[quote=Evan Wray;153709]Yes it is cold here in Edmonton also very jealous of the golfing in shorts.Will be doing the same when we go to our place in Casa Grande in january, how's business in Tucson?

SLOWWW