hand-held mortar Doubt

Hi folks!, im just starting a new campaign, and a doubt about hand-held mortar trhough walls and buildings has apeared.
How does the impact works if the dispersión goes trhough a wall or building?
In case a miniature its inside a building can a dispersed shot from outside impact that miniature? what happens with multiple floors in a building?
Thanks

Oh dear, seems like no-one feels up to answering questions about the Nemesis Crown supplement.

Honestly, there's probably no 'official' answer to this, so whatever you can agree on within your campaign group will be fine. In a situation where you can't agree, common advice is for players to roll off to decide whose opinion 'wins' for the duration of the game, & make a group decision after.

I'd say given the nature of the weapon -- a conventional explosive -- the blast & shrapnel will be stopped by walls, so the dispersion can't pass through solid walls. Eye it in, basically, & if cover looks like it would stop a bomb, then it stops the bomb.
Either way, the blast would travel up & down the same way it travels sideways, so the blast can only expand 1 1/2" above or below the target. That should cover multiple floors.

Alternatively, introduce some house rules on explosives blowing up terrain, because that'd be fun.... Hope this helps!