Epoxy Anchor into a Foundation Wall

[phamENG]

So I'm 99% sure this is a bad idea, but I like this client and want to make sure I leave no stone un-turned.

House is a slab on grade, but they want a brick skirt. Unfortunately, the owner doesn't like thin brick - something about not wanting the fake stuff (as I spent my morning assessing a 120 year old building with 20" brick walls, the irony of thinking 4" veneer is some how the "real" stuff is not lost on me). So this is the detail the architect gave me and is insisting they've used it before. Even showed me the engineer's detail to match. (I wasn't impressed and I'm pretty sure the proprietary anchor they used violated a few manufacturer's installation restrictions.) We end up with a single wythe of brick veneer and one of 8" CMU with a shoe block and a slab. Well the anchor bolts are going to end up somewhere very close to the collar joint between the brick and the block - probably more in the brick.

A quick check of the most common adhesive anchors for unreinforced brick - Hilti HIT-HY 270 and Simpson ET-HP, everything is about anchorage into the face of the wall. Hilti specifically says it has to be in the face; Simpson seems to imply it at least - there may be a specific note buried in there somewhere that I'm not seeing.

So...does anyone think this is salvageable? I don't, but like I said, figured I'd cast a wider net and see if anyone can pull a rabbit from their hat.

 

[phamENG]

Hmmm...I may have solved the tension...12" block below grade and set that as my "top of CMU" line for embedment calcs. But shear....do I have a 5/8" threaded rod in bending through that couple feet of veneer? And potential differential movement of the bricks and the masonry/slab...Hmm...

 

[EZBuilding]

This is a tricky one. With your last solution seems like you are proposing to have 4" brick next to and 8 inch block with a 12" block below. Doesn't seem like there is much room for the collar joint there. Looks like fractions of a few inches are going to make the difference here - I probably would lean towards require a cast in place anchor versus a post-installed solution...

I think you are going to have to use some engineering judgement here - unless masonry geek can come save the day.

I'll throw out an outside of the box thought - any consideration to blowing out the back face of the 8 inch block so that your anchor can be set within that grout blob?

 

[phamENG]

Yeah - the second post considers a cast in anchor that will have the brick mason cursing my existence for a while. Lots of cuts in the brick to make it fit around the anchors.

My judgement is that it's a bad idea...masonrygeek come and convince me that it can work...or not. I'm really okay if it doesn't, but I want to be sure of my answer when they demand I convince them it doesn't work...

I like the knocking out the face idea. I think it helps the situation...though I'm not sure it's directly quantifiable unless they split the brick in half to have enough around the anchor...but then why not just use thin brick...

 

[XR250]

It is nothing for a mason to cut around an anchor bolt or cut out the face of the block.
Maybe cut out the faces of a few blocks and use one of these....

https://www.homedepot.com/p/Simpson...in-x-17-5-8-in-Anchor-Bolt-SSTB16-R/202329554

 

[Ron]

In your first sketch, you are depending on the shear-bond strength of relatively low strength mortar. I would give it 10-25 psi.
The second one is an anchor....what you need. A good mason can work it out.

One other option is to increase the sill width and anchor into grouted filled cells in the concrete masonry. Yes, you will have to consider the eccentricity for uplift, but that is likely do-able.

 

[phamENG]

Thanks. XR - I'll see if I can convince myself that the SSTBs work here. Good for concrete, sure, but I'll have to see if they're tested and rated for grout filled CMU. If so, that's probably the way to go.

Ron - thanks. That's why I didn't like the first one. The second I still don't like as the top foot or so of the anchor depends on either the mortar in the collar joint for shear transfer or a very small amount of grout around it. Increasing the sill/sole plate won't fly - the studs would have to get larger, too, since this is a finished space. Wouldn't do to have the sole plate of the wall sticking out from under the GWB when the trim carpenter shows up to put in base boards...

 

[phamENG]

Well look at that. Thanks, XR. I'll see if I can get the dimensions to work. Could have sworn that page wasn't in the catalog last time I was looking at these...

 

[MotorCity]

Not sure if you have shear, tension, or both in the anchor rod, but to take shear out of the picture, you could use some light gage metal straps between the floor and bottom of the wall. I am guessing there is little if any net uplift (tension) in the anchor rod?

 

[phamENG]

Loads vary. Waterfront, so some areas are high shear, some high tension, some both.

The strapping is an interesting idea. I've used it under wood floors at sill to CMU for retrofits - never considered it here. I'll have to check the finish schedules and see if it would cause issues. Thanks.

 

[MJCronin]

Dumb idea from a browsing Mechnical Engineer ....

Would it be possible to test a few of these ?

Perhaps a test wall could be constructed at reasonable cost ... perhaps there is an old house or wall somewhere that could be used

Maybe HILTI would be willing to throw a few bucks at such a testing program ???

Just an idea ....

MJCronin
Sr. Process Engineer

 

[phamENG]

MJCronin - I guess you found the one stone I'm willing to leave unturned. Nobody involved is going to be willing to take the time or pay for testing. Thanks for the thought, though.

 

[EZBuilding]

MotorCity/Pham - could you guys expand on the metal strap concept?

Pham - where would you get if you ran the numbers for anchor bolts in TMS 402 for the brick f'm? Might give you a sense of a lower bound capacity there...