Cement block girder support

[Richard Mangold]

Is this support for a wood girder ok? The lower portion was mortared but the top block was not. There were 3 columns like this in the crawl below a 1 story add-on (den) to a 1959 ranch house. Should all block have been mortared?

[KEVIN WOOD]

NO! They should have been installed parallel not lateral to provide full support under the beam or girder not across the beam. They will snap in the middle 1/3 of the CMU if not supported correctly underneath.

[Richard Mangold]

I should have include this in my post: I am not sure if it is a CMU or solid cement block since there was no access. The entry was blocked by a hopper window that I reached over to snap the photo.

[Marcel R. Cyr]

http://www.raisedfloorlivingpro.com/footings.shtml

[KEVIN WOOD]

Into the vault that one goes!

[Richard Mangold]

Marcel, thank you. I am still a little confused and need verification of my interpretation. My structure did not exactly meet any of the fig. 10 examples. So, since mine are lateral and not interleaved like brick even though doubled I think I interpret this as not according to standards of practice. Yes? Also I am planning on disclaiming that they may not be resting on any footers since I could not access the crawl to observe them.

[Robert J. OConnor]

Unless you are in a high seismic/wind risk area, where all supports need to be tied down, I don't think just the top block not being mortared in place is such a big deal at all. For most houses, piers are only resisting vertical gravity loads, and there are no lateral loads ... like on exterior walls which need to have fully mortared joints up to the sill plate, with sill plate anchors.

I can see why they didn't mortar the last course as it likely would have made the top of the pier just a little too high. Another option would have been to build up the top of the pier with mortared brick (see attached), which is less stable over time in my opinion. In either case however, the top course/block should be filled solid with mortar or have at least 4" of solid masonry ("pier cap" per IRC R606.6.1). It's not likely that was done.

Intermediate piers typically have a shim or spacer without tie downs, and uplift loads are at the perimeter where anchor bolts tie down the structure to the foundation. So essentially that last block is acting like a large shim. And the pier blocks do not need to be orientated parallel to the joists unless the spans are marginal, and you want to reduce the span a little.

About the footing, I think it's a good thing that you cant see it. You typically shouldn't be able to see that, except maybe for a deck. And that doesn't look like a Harry Homeowner "fix" for sagging floors where I would suspect no footing. Just look for possible signs of no footings (e.g. uneven floors or sagging beam).

One concern I do have is that the wood beam appears to be in direct contact with the masonry pier, and there should be something to separate the masonry and the wood (which is likely not treated, and it doesn't appear to be). Was there a thin metal plate/shim or some type of tar paper between the two?
.

[Marcel R. Cyr]

606.5 Piers.
The unsupported height of masonry piers shall not exceed ten times their least dimension. When structural clay tile or hollow concrete masonry units are used for isolated piers to support beams and girders, the cellular spaces shall be filled solidly with concrete or Type Mor S mortar, except that unfilled hollow piers may be used if their unsupported height is not more than four times their least dimension. Where hollow masonry units are solidly filled with concrete or Type M, S or N mortar, the allowable compressive stress shall be permitted to be increased as provided in Table R606.4.

606.5.1 Pier cap.
Hollow piers shall be capped with 4 inches (102 mm) of solid masonry or concrete or shall have cavities of the top course filled with concrete or grout or other approved methods.

[KEVIN WOOD]

Correct

[Robert J. OConnor]

Yes marcel, those are the correct references for what I was talking about.

The unsupported height appears to be just under 3 block courses or 24", for a hight to least dimension ratio around 3, which is less than 4 for a required solid grouted pier per IRC R606.5

And R606.5.1 is the reference for the cores of the top block to be filled ("pier cap"), so that the masonry contact bearing stresses are not excessive. By the time the load gets to the first joint, bearing stresses have distributed to the point where grouting is not needed.

[Jeffrey R. Jonas]

The pic reminds of a "dry stack" built home. Only difference is there should be a 'bond coat' applied. Perhaps they filled the cores instead.
http://www.drystacked.com/sequence.html

[Marcel R. Cyr]

Yes Jeff, Dry Block and surface boding cement (SBC) have been around for a long time. Seen and used it before.
We call it Structural Skin Mortar.
Here is another link on the subject.

https://www.thenaturalhome.com/drystackblock.htm

[Robert J. OConnor]

Never really like dry stacked block walls, cause the bending strength relies primarily on just the grouted rebars. Grouting is very tricky sometimes, and you can end up with grout voids (can pick those up with an IR camera). And its much weaker than a mortared block wall with the same rebar.

In any event, I wouldn't flag the piers for repair unless you saw indications of poor performance (e.g. crushing or deterioration of the beam indicating excessive bearing stress or cracked pier blocks). Assuming it's performing well, just make a note of it ... and you could also recommend monitoring if you couldn't verify adequate bearing or separation.

[Joe Funderburk, CMI]

Originally Posted by kwood

NO! They should have been installed parallel not lateral to provide full support under the beam or girder not across the beam. They will snap in the middle 1/3 of the CMU if not supported correctly underneath.

Is there a code you can cite that specifies the direction of the CMU in relation to the beam?

[Joe Funderburk, CMI]

Originally Posted by rmangold

Is this support for a wood girder ok? The lower portion was mortared but the top block was not. There were 3 columns like this in the crawl below a 1 story add-on (den) to a 1959 ranch house. Should all block have been mortared?

Hollow block is a highway for termites.


2009 IRC R606.6 Piers. The unsupported height of masonry piers shall
not exceed ten times their least dimension. When structural
clay tile or hollow concrete masonry units are used for isolated
piers to support beams and girders, the cellular spaces shall be
filled solidly with concrete or Type M or S mortar, except that
unfilled hollow piers may be used if their unsupported height is
not more than four times their least dimension. Where hollow
masonry units are solidly filled with concrete or Type M, S or N
mortar, the allowable compressive stress shall be permitted to
be increased as provided in Table R606.5.

R606.6.1 Pier cap. Hollow piers shall be capped with 4 inches
(102mm)of solid masonry or concrete or shall have cavities of the
top course filled with concrete or grout or other approved methods.