Bonding between rows (wythe) of existing masonry wall

[Oz46]

I have come across an existing exterior masonry wall that appears to be constructed out of 6" concrete block and 4" brick. The building is a 60 years old warehouse building. There is no indication of any bonding between the two masonry members (wythe) and the wall is about 16 ft high. There are some stepping cracks on the brick (exterior) around overhead doors but not many visible cracks on the interior side (blocks).
1) Is there anyway that we can verify if the two wythe are actually bonding? As mentioned I don't see any running bond between the two neither from inside nor from outside of the building.
2) In absence of any existing bonding between the two wythe, is there any suggestion how to bond the existing brick and block without tearing down the whole wall?
Any comments or suggestion is very much appreciated.

 

[kipfoot]

1) I think the simplest way to check is to do some selective demolition. If you were to choose a couple 3'x3' (or 2' wide by 3' high or whatever) areas where the brick can be carefully removed, you would be able to see what type of ties were used between wythes, if any.

2) I haven't personally used these, but heliflex might be a good retrofit option in this case. These would at least allow you to share surface pressure loads. Whether they allow you to consider the separate wythes to act compositely is another question.

 

[dik]

Can you tell from the outside surface of the brick that you have 'header' bricks connecting the two walls together? With CMU units on the inside, they often had 'notched' CMU units to accommodate the header bricks. This should effectively tie the two wythes together. They also sometimes used 'S' or 'Z' bars to tie the wythes together. Later walls used steel and some earlier ones used wrought iron.

It may be a matter of doing some some exploratory work.

Careful, for a 10" wall you are near the max for an h/t=20 (common codes at the time).

Dik

 

[Oz46]

Thank you kipfoot for your help and comments. I agree with your suggestion in doing selective demo. I also checked the Helifix wall ties anchors you've mentioned. I am not familiar with this product but I will dig into it. Thank you so much.

 

[HouseBoy]

I have seen horizontal joint reinforcing used to tie wythes together for that age of masonry.
A metal detector might be effective to locate it.
Other than that, I agree with the others that selective demo might be needed.

I've never used Heliflex anchors (retrofit ties) but I like them in concept and they do seem like a good product.
I'd be interested to see your results if you do end up using them.

 

[Oz46]

Hi dik. Thanks for your comment. I looked for the header bricks but couldn't find them from the exterior side. That was the first thing that got me concerned. It is possible that they may have some sort of ties to tie the two wythe together, as there are not too many visible cracks on the walls, I have to do some investigation as kipfoot suggested. Yes, you are right the maximum allowable height is very close to the existing height as well. Thanks.

 

[Oz46]

Thank you HouseBoy. I agree we should do some investigation to ensure there are bonding between the two wythe. I will post the results if we end up reinforcing with retrofit ties.

 

[Ron]

I have used expanding foam adhesive to tie bricks to an existing wall. You'll have to do a little experimenting, but it works. Used it on a 10 story historic building almost 20 years ago. Seems to be working well and has the advantage that you don't compromise any cavity waterproofing on the backing wall.

 

[dik]

Ron: a polyurethane adhesive?

Dik

 

[Ron]

Dik....yes.

We injected dollops of the foam, trying to make each one about 1/2 sf, spaced 18 to 24 inches apart in a grid. We did an injection pressure experiment in the lab to make sure we didn't blow the brick off the wall!

 

[dik]

Thanks Ron... put into my piggy bank for later use.

Dik

 

[OldBldgGuy]

I've used Helifix and Spiralok in Canada & I'm sure there are others available in the US. They have so many good qualities and good support documentation to enable you to actually design the installation, as opposed to a wing & a prayer which is the popular alternative. They work for many different back-ups as well, I've even used them to tie brick veneer to wood frame.

 

[Oz46]

Thank you Oldbldgguy.