D&D General Did my players knock down an apartment building (in game)?

[Jacob Vardy]

One of my parties is exploring underneath a city. As the city is 1500+ years old, most of the buildings are built on older buildings. With some difficulty people can move between the buried remains of these buildings.

The party found a trap door leading up. it was propped up and nailed shut from below. Fearing to open it by hand, they decided to use black powder charges. The chamber they were in was about 4m x 2m x 1.5m. I narrated that this volume was swiftly filled with a flow dirt and debris.

Most buildings in the city are 4-6 story masonry. What happens when you remove 12 cubic meters from beneath a large building? If anyone knows i am kinda curios?

 

[Deset Gled]

You basically made a small sinkhole. Google "sinkhole under apartment building" and you'll find multiple images of this happening in real life.

The short answer is that it might not cause a complete collapse, but will cause at least some structural damage. In more modern and/or lawful civilizations with building codes this would lead to immediate evacuation and condemnation of the building; if the party gets caught there could be very serious charges.

 

[Blue]

One of my parties is exploring underneath a city. As the city is 1500+ years old, most of the buildings are built on older buildings. With some difficulty people can move between the buried remains of these buildings.

The party found a trap door leading up. it was propped up and nailed shut from below. Fearing to open it by hand, they decided to use black powder charges. The chamber they were in was about 4m x 2m x 1.5m. I narrated that this volume was swiftly filled with a flow dirt and debris.

Most buildings in the city are 4-6 story masonry. What happens when you remove 12 cubic meters from beneath a large building? If anyone knows i am kinda curios?

Three thoughts:

1. I'm assuming they used an appropriate sized charge for the door, not an extravagant one. So I'm not assuming significant blast damage beyond the trapdoor.

We know from your description that it swiftly flowed down. If it was foundational it would likely be either solid, stuck in place by weight, or just slam down since it carries so much weight. So the description makes me feel that it was loose debris and dirt in some other chamber. Now, it might be holding up a roof in that room which is a floor elsewhere, but from the description I think they lucked out.

From your description, it doesn't sound like massive amounts of dirt and earth were brought in to create an earth level before building the higher structures. Rather, it's buildings, buildings, buildings all the way up. That supports that this was detritus in a chamber. There's no loose earth to form a sinkhole and fall in.

2. Another way to think about it is was the trapdoor of sufficient sturdiness to hold up a portion of the building? If not, then the weight would have previously collapsed the trapdoor. I didn't start with this thought though, because you did mention "propped up", and if that was a massive prop then it might have been.

3. A third way to think about it is - which way will your players have the most fun? (Completely separate from will the characters succeed.) By this measure, it likely fell if your players are like mine.

Have fun!

 

[aco175]

Have the building me just unstable until the PCs climb up and look around. The noise would have awaken whatever is in the building and it would come looking. Make something fun of the PC's trying to escape a falling building. You can have it like the movies, where it falls into the next building and stops for a couple rounds while the PCs fight whatever is trying to kill them- fall some more which may split the party for a few rounds. Have it fall some more into another building, but make it clear that there are no more building to slow it down next time. Players need to finish the fight or escape and/or rescue villagers or other PCs.

 

[Paul Farquhar]

Players accidentally causing mass destruction is quite a common occurrence in our group’s games. We burned down the docks district, sunk a floating island, exploded a 100 ft. tall dragonshard, etc. so collapsing an apartment building is small beans.

 

[BookTenTiger]

The good news is they can replace it with a much more profitable high rise!

 

[Jacob Vardy]

You basically made a small sinkhole. Google "sinkhole under apartment building" and you'll find multiple images of this happening in real life.

The short answer is that it might not cause a complete collapse, but will cause at least some structural damage. In more modern and/or lawful civilizations with building codes this would lead to immediate evacuation and condemnation of the building; if the party gets caught there could be very serious charges.

Thank you. I had no idea that this was a thing... Some really spectacular images.

Three thoughts:

1. I'm assuming they used an appropriate sized charge for the door, not an extravagant one. So I'm not assuming significant blast damage beyond the trapdoor.

We know from your description that it swiftly flowed down. If it was foundational it would likely be either solid, stuck in place by weight, or just slam down since it carries so much weight. So the description makes me feel that it was loose debris and dirt in some other chamber. Now, it might be holding up a roof in that room which is a floor elsewhere, but from the description I think they lucked out.

From your description, it doesn't sound like massive amounts of dirt and earth were brought in to create an earth level before building the higher structures. Rather, it's buildings, buildings, buildings all the way up. That supports that this was detritus in a chamber. There's no loose earth to form a sinkhole and fall in.

2. Another way to think about it is was the trapdoor of sufficient sturdiness to hold up a portion of the building? If not, then the weight would have previously collapsed the trapdoor. I didn't start with this thought though, because you did mention "propped up", and if that was a massive prop then it might have been.

3. A third way to think about it is - which way will your players have the most fun? (Completely separate from will the characters succeed.) By this measure, it likely fell if your players are like mine.

Have fun!

Good stuff. 1) & 2) really help me visualise some options. Particularly that it can't have been foundational because it would have already collapsed. 3) was always in play, because "the party gets hanged by outraged survivors" only appeals to a certain type of player.

Thank you.

 

[Blue]

Players accidentally causing mass destruction is quite a common occurrence in our group’s games. We burned down the docks district, sunk a floating island, exploded a 100 ft. tall dragonshard, etc. so collapsing an apartment building is small beans.

Waterdeep has an Exploding Manhole day thanks to The Company of the Unicorn (our party), many sewer adventures each about a year apart, and that in AD&D 2nd fireballs were volume filling plus methane was flammable.

 

[Jacob Vardy]

Waterdeep has an Exploding Manhole day thanks to The Company of the Unicorn (our party), many sewer adventures each about a year apart, and that in AD&D 2nd fireballs were volume filling plus methane was flammable.

First time for me, the party dropped a kilometer long adamantine chain anchoring a Zhent floating temple over the forests of Daggerdale. There was some question if the PCs had cracked Faerun like an egg. Instead, they just set a large part of the Dales on fire.