expanding foam in brick work behind shower

[hellopeter]

Hi folks,
A question about prep work in a bathroom. Specifically on a wall where a shower will go.
After stripping a shower wall back to brick, revealed older brick alongside newer brick.
the older brick had missing mortar in a few areas.
The bricks are old but solid — no wobble or major movement.
Tapping on them they sounded hollower than the new brick.

The installer filled the gaps with expanding foam, then fixed moisture-resistant boards over the top. The plan is to skim and tile onto that.

Is this a standard method? wondering if this will cause issue down the line.

Appreciate any thoughts.
Cheers

 

[cdbe]

If it's nothing structural, ie a few bricks rather than half your house, it will be fine.