Fireballs in wooden buildings

[Torek]

Greetings and Salutations,

I have a question regarding the rules for fireballs in wooden buildings. Basically it is DMing question, I hope this is the right place to ask it?

Picture a 40 by 40 foot kitchen in the basement of a two storey house with wooden walls and wooden floor.

You let a fireball explode in the southern corner of this room so that of the full blast only a quarter can effect the room.

How should the resulting fire evolve and how can the player characters put this fire out again? After how many rounds might it be out of control if no quenching attempt has been made?

[Khantalas]

You know, technically, fireball just inflicts fire damage. There is no mention of wood inflicted fire damage being ignited.

[Dhavaer]

Fireballs can't set fire to things. The room would just take half damage minus hardness, same as any other object.

[Bender]

The fireball sets fire to combustibles...

It's up to the DM how combustible the wood of a structure is. Generally, the heavy wooden beams wouldn't catch fire very easily, but any paper/cloth would probably catch fire. A tablecloth catching fire might set the table and the chairs on fire. Once the furniture is burning, there is a risk of the walls starting to burn...

I don't think the structural beams would really catch fire within the first half hour.

If there is almost no or no cloth/oil/paper/small dry twigs... in the room, the fireball is unlikely to do more than initial damage. Unless there's a lot of those, it would be reasonably easy to extinguish the fire.

I guess it's mostly a question of whether or not you as a DM wants the house (and probably the rest of the city) to burn down every time someone casts a fireball...

[Tor the Fallen]

I dunno, a ball of fire hot enough to melt metal and kill people in less than 6 seconds seems like it'd be able to set wood on fire, even if there aren't any rules for it.

[Namillus]

Er, combustibles in a Fireball's area of effect do catch light. It says as much in its PHB entry.

However, that probably means easily combustible substances, like alcohol. Wood might be a bit trickier to adjudicate.

EDIT: Lousy ninja. Whatever happened to the Inverse Law?

[Lord Lorac Silvanos]

If the room was drenched in oil or alchemist fire it would work though ;-)



Edit: Another late post brought to you by your friendly neighborhood Elder Orb Beholder.

[Caledonian]

The whole point of alchemist's fire is that it doesn't need an external source of heat to burn strongly.

[Khantalas]

It can set things to fire but it can't shatter beyond glass?

That is stupid, I tell you.

[Tor the Fallen]

It can set things to fire but it can't shatter beyond glass?

That is stupid, I tell you.

What can't shatter class?
A fireball goes through glass, no problem.

[Lord Lorac Silvanos]

I think he meant anything stronger than glass. (At least that is what he wrote)

[Khantalas]

No, it shatters glass. But RAW, since it has no line of effect behind it, it doesn't go beyond it.

There was even an article on Wizards about it.

[Tor the Fallen]

f the damage caused to an interposing barrier shatters or breaks through it, the fireball may continue beyond the barrier if the area permits; otherwise it stops at the barrier just as any other spell effect does.

Glass hardness: 1 Hp: 1/inch of thickness

A fireball is gonna go through, unless you have a foot or two of glass.

[Khantalas]

Hmm... I thought that was just lightning bolt.

Now, that article said the stupidest things. Is it true that glass provides total cover to anyone behind it?

[Lord Lorac Silvanos]

It does block line of effect. (At least for the first attack, but, as you saw, the Fireball does not care.)

[martyboy74]

Hmm... I thought that was just lightning bolt.

Now, that article said the stupidest things. Is it true that glass provides total cover to anyone behind it?

Why wouldn't it? It's a solid object between you and something else.

[Dreyden]

SRD:
If the damage caused to an interposing barrier shatters or breaks through it, the fireball may continue beyond the barrier if the area permits; otherwise it stops at the barrier just as any other spell effect does.

The article on Wizards was wrong. They do that all too often.

[Khantalas]

Hmm... So a magical crossbow bolt would shatter the entire glass if it's less than 2 inches thick in one shot (gah?), but won't hit anything beyond it (even more gah?)?

[Tor the Fallen]

Why wouldn't it? It's a solid object between you and something else.

You ever thrown anything through a window?

[Bender]

No, it shatters glass. But RAW, since it has no line of effect behind it, it doesn't go beyond it.

Since a fireball isn't an explosion, and there is no pressure build up, the glass won't necessarily shatter. It would melt.

if the heating is not homogeneous, the glass might break because of thermal expansion before it melts, but that wouldn't really make a difference

[Lord Lorac Silvanos]

Hmm... So a magical crossbow bolt would shatter the entire glass if it's less than 2 inches thick in one shot (gah?), but won't hit anything beyond it (even more gah?)?

You can house rule that it continues and simply modify the potential damage by how many HPs it took to get through the barrier.

[Torek]

Could we stay with my question, please?

Does anybody have rules or homebrewn rules for fireballs in wooden buildings and how there might result a fire from it?

[martyboy74]

You ever thrown anything through a window?

How often does the things that you're throwing through said window go exactely where you wanted?

[Sahegian]

Here is a house rule I tried for something similar:

Since it does damage to inanimate objects have anything flammable that takes more damage than it can withstand be considered on fire and allow it to burn for 1 round per original hit point doing 1 point of fire damage to any item it is touching in that time. Once a floor or the walls or ceiling catch fire, then it is pretty much impossible to stop without having some handy magical way of extinguishing it.

I think it is a reasonable representation, but the book keeping got to be such a burden that I just ended up rolling some dice and making it up on the fly.

[Lord Lorac Silvanos]

Could we stay with my question, please?

Does anybody have rules or homebrewn rules for fireballs in wooden buildings and how there might result a fire from it?

RAW: no fire will result without any combustible material present.

If combustible material is present (or you want to house rule a fire anyway) DMG II, page 48 has rules for burning buildings and the DMG page 304 (can also be found in the SRD) has rules for different kinds of heat/smoke/fire related dangers.

[Bender]

You could assign a number of rounds for the easily combustible things like cloth and paper to set the furniture on fire (I'd make it less than a minute, depending on how much of it is present) and then a number of minutes for the furniture to set the rest of the building on fire (thick wooden beams are slow to burn)

If there isn't too much of easy combustibles, they should be reasonable easy to extinguish by beating out the flames, covering them with a blanket... but it gets harder every round (you can say that the fire spreads 5 or 10 ft every round, e.g., and it you can only extinguish the flames in one square of 5 ft/round by beating them)

Once the furniture is on fire, it gets much harder, and a lot of water/sand/magic is necessary to put it out again
When the structure is burning (which should take at least 10 minutes or even longer) it is lost. Time to start worrying about the neighbouring buildings.

[Shhalahr Windrider]

Hmm... So a magical crossbow bolt would shatter the entire glass if it's less than 2 inches thick in one shot (gah?), but won't hit anything beyond it (even more gah?)?

The bolt may go through, but it will be deflected in a rather unpredictable manner.

I recall an episode of Mythbusters (one of the few I've ever seen, as I don't have cable at my own house) where they tested the possibility of a person shooting at a sniper in such a way that the bullet passes through the sniper's gun sight and into his eye and brain. They were unable to make such a shot work as described. Every bullet that entered the gunsight was deflected by the lens. The bullet instead hit the sides of the sight, causing it to burst apart. Though the event would surely have killed any real sniper, the bullet never hit the target dummy's eye.

And it seems to me a crossbow bolt has far more potential to be deflected than a modern bullet fired from a modern gun.

[Roethke]

There's a pretty simple houerule to figure this out-- the house is wooden, hence combustible. Whether it actually catches fire is a function of how much damage the fireball does. The ruling being, if you reduce a wooden object to below 0 hp by fire damage it is considered "on fire".

And remember, before hardness, objects take half damage from fire.

In this case, your average 10d6 fireball will do, 18 damage, before applying hardness.

According to the SRD, wood has hardness 5, with 10hp/inch of thickness. So the fireball will probably burn through 1" planks (which are pretty flimsy), and the 2" planks will be singed badly but won't burn.

for a 5d6 fireball, maximum damage the wood could take is 15, so you'd just barely get 1" planks to burn (reducing them to 15dmg -5 hardness - 10hp = 0 hp).

[Inyssius Tor]

^^But every single bullet fired went through the glass part of the scope like butter. A rifle scope is more than just a lens on one end, a tube, and another lens on the other end.

And they actually succeeded when they tried again on another episode.

^Uh, there's a difference between "on fire" and "irreparably destroyed".

[Roethke]

^Uh, there's a difference between "on fire" and "irreparably destroyed".

Well, I was reading below 0 hp as "broken" as opposed to "reduced to ash". If you have a wooden object on fire, I'm pretty sure, even if you manage to put the fire out, it won't be able to be used for its original purpose.

EDIT: Of course, of course, houserule disclaimer, etc.