Connecting wood ledger to Terra Cotta block

[Fatboycowen]

I have a job where the existing house's exterior walls are entirely built using Terra Cotta block. The block is 3 cores, about 7.5" thick, and is probably 10"x10" (don't have exact dimensions, but can get them easily).

The job consists of attaching several ledgers to the outside of the building at or near the 2nd floor level, to attach an addition. One addition is a 2nd story roof deck, with room below. Another is a simple gable addition off the side. Luckily the designer is using existing openings.

I need to attach the ledger to the outside of the terra cotta block, which will receive flush mounted wood joists.

Hilti has their HY20 anchor, which has been tested in this (or a similar) application. However, they specify a maximum thickness of attaching member of 3/4". I assume this is because it is correctly assuming we are attaching through a thin walled clay tile, and moment on that wall is limited.

Questions:

Should i use a wood ledger with the HY 20 screen anchors, and use the load tables (i have about 420 pounds per foot shear force at that ledger).

One idea i had was to drill a hole in the tile, inject grout somehow, and then drill in regular epoxy anchors. What do you think of that? What kind of injectable grout products are available that might work?

Any other ideas or considerations?

This is my first post, but this forum is excellent so far!

Thanks in advance!
Jon

 

[csd72]

When I have had a similar situation I cast 12" square concrete pads into the wall at the anchor locations.

 

[Fatboycowen]

That's an interesting idea. However, the terra cotta block is just painted on the exterior. The blocks don't necessarily line up with the ledger perfectly, so these concrete patches would show above the ledger, which is why i considered doing some sort of grout injection.

Thanks,
Jon