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Torek
2007-04-20, 06:00 AM
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
2007-04-20, 06:02 AM
You know, technically, fireball just inflicts fire damage. There is no mention of wood inflicted fire damage being ignited.

Dhavaer
2007-04-20, 06:10 AM
Fireballs can't set fire to things. The room would just take half damage minus hardness, same as any other object.

Bender
2007-04-20, 06:18 AM
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
2007-04-20, 06:21 AM
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
2007-04-20, 06:21 AM
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
2007-04-20, 06:23 AM
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
2007-04-20, 06:39 AM
The whole point of alchemist's fire is that it doesn't need an external source of heat to burn strongly.

Khantalas
2007-04-20, 06:41 AM
It can set things to fire but it can't shatter beyond glass?

That is stupid, I tell you.

Tor the Fallen
2007-04-20, 06:44 AM
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
2007-04-20, 06:45 AM
I think he meant anything stronger than glass. (At least that is what he wrote)

Khantalas
2007-04-20, 06:47 AM
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
2007-04-20, 06:49 AM
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
2007-04-20, 06:52 AM
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
2007-04-20, 06:58 AM
It does block line of effect. (At least for the first attack, but, as you saw, the Fireball does not care.)

martyboy74
2007-04-20, 06:59 AM
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
2007-04-20, 07:00 AM
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
2007-04-20, 07:01 AM
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
2007-04-20, 07:02 AM
Why wouldn't it? It's a solid object between you and something else.

You ever thrown anything through a window?

Bender
2007-04-20, 07:02 AM
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
2007-04-20, 07:13 AM
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
2007-04-20, 07:13 AM
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
2007-04-20, 07:14 AM
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
2007-04-20, 07:23 AM
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
2007-04-20, 07:29 AM
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
2007-04-20, 07:38 AM
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
2007-04-20, 08:06 AM
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
2007-04-20, 08:19 AM
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
2007-04-20, 08:22 AM
^^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
2007-04-20, 08:47 AM
^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.

Justin_Bacon
2007-04-20, 08:54 AM
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.

The rules in the DMG II are useful for pre-designing a burning building, but don't actually provide any meaningful insight into starting fires or the actual spread of the fire. (IIRC, the only rule for spreading the fire is that it encompasses another 10' x 10' area every minute. So the spread doesn't vary by fire and is basically left to the DM's discretion.)

The rules below have been adapted from PTOLUS with an eye towards streamlining them for easier use and reference. See the rules under "spreading the fire" for how burning objects and fire damage can lead to a space lighting on fire.

If you're in a flimsy wooden shack with walls, floor, or ceiling only 1 inch thick each 5 foot space would be considered to have 10 hit points and hardness 5. Halve the damage from the fireball (since it's an energy attack against a space) and then apply the hardness: If the total exceeds 5 points of damage, the flimsy wooden shack would light on fire.

Walls in a typical house (like the one I'm in now) are closer to 5-6 inches thick. They'd have 50-60 hit points and you'd have to deal 25-30 points of damage (after halving for the energy and applying the hardness) to get a fire going.

If you've got a lot of combustibles (a room full of paper, for example) they may catch on fire (see the DMG for those rules). A space with objects in it on fire takes 1d6 points of damage each round (but it's halved and then hardness is applied -- so unless there are multiple objects in the space it's not going to deal damage at all).

All that being said, the rules are not entirely satisfactory when it comes to fireballs: The fireball deals a uniform damage. So either the entire room catches on fire simultaneously or none of it does. If you want a more varied result, consider making another exception to the normal rules and, if the fireball would deal enough damage to potentially start a fire, allowing each space to make a Reflex save for half damage.



FIRE



(Adapted from Ptolus)


BASIC FIRES
A large fire is treated like a mindless construct with the following stats:

-Construct [fire]
-1 HD (1d10) for every 5 ft. square it occupiesplus bonus hit points per a construct
-Size determined by the number of squares it occupies
-No ability scores except for Dexterity 15
-Immune to all attacks except water, cold, and smothering attacks
o 1 gallon of water causes 1d6 points of damage
o Smothering a fire with a blanket causes 1d6 points of damage
o A quench spell destroys it completely
-BAB = HD (per cleric)
o do not adjust for size
o add Dexterity (per Weapon Finesse)
A fire can attack adjacent creatures, objects, or squares each round. It can make a number of attacks based on its size (see table).

FIRE SIZE-----BONUS HIT POINTS-----# OF ATTACKS-----EXTREME HEAT
MEDIUM-----20-----1-----5 FT.
LARGE-----30-----2-----10 FT.
HUGE-----40-----3-----15 FT.
GARGANTUAN-----60-----4------20 FT.
COLOSSAL-----80-----5-----25 FT.

SPREADING THE FIRE: When the fire attacks an adjacent square, it hits automatically and deals 1d6 points of damage. This is energy damage and is therefore halved against inanimate objects (although the DM can rule that certain materials are more vulnerable to fire and double this damage back to normal). The hit points of a square are determined by either its floor, wall, or ceiling (whichever is lowest).

Any items in the space being attacked are also struck by the fire and probably catch on fire. If an object in a space is on fire, the space it’s in also takes 1d6 points of damage each round.

As a special exception to the normal rule, accumulate all damage from a spreading fire into a single total for the round before applying the space's hardness.

Once a square has lost half its hit points, the fire spreads to that square (increasing its size). However, once the square loses all of its hit points, the fire will burn out in that square (decreasing its size).

CHALLENGE RATING: A fire of size Large or smaller is CR 2. Larger fires are CR 4. Collapsing attacks or dangers increase the Challenge Rating by +1.


BUILDING COLLAPSE
Characters in a building with wooden ceilings and floors that have been burning at least 10 rounds may face collapse. There is a 20 percent chance each round in such a burning building that a character faces a +10 attack from a falling rafter or bit of ceiling; an attack that hits inflicts 2d6 points of damage. If the fire has been burning for ten minutes or more, the entire ceiling might collapse instead (20 percent chance each round). In such a case, no attack roll is needed—all characters within suffer 8d6 points of damage (Reflex save, DC 15, for half damage).


CHARACTERS IN A FIRE

CATCHING ON FIRE:Creatures or objects struck by a fire suffer 1d6 points of damage. They are also at risk of catching on fire and must make a Reflex save (DC 15) to avoid this fate. If a character’s clothes or hair catch fire, they take an additional 1d6 points of damage immediately. In each subsequent round, the burning character must make another Reflex saving throw. Failure means they takes another 1d6 points of damage that round. Success means that the fire has gone out. (That is, once they succeed on their saving throw, they are no longer on fire.)

A character on fire can automatically extinguish the flames by jumping into enough water to douse themselves. If no body of water is at hand, rolling on the ground or smothering the fire with cloaks or the like as a full round action permits the character another save with a +4 bonus.

Those unlucky enough to have their clothes or equipment catch fire must make a Reflex save (DC 15) for each item. Flammable items that fail take the same amount of damage as the character.

Objects on fire do not benefit from their hardness.

IN A FIRE: Characters moving through a fire provoke an attack of opportunity from the fire (there is no limit to the number of attacks of opportunity a fire can take). Characters who end their turn in a fire are automatically hit by the fire.

HEAT DANGERS: Characters in a burning building are considered to be in severe heat. Those standing close enough to the fire are considered to be in extreme heat (see table for the danger distance, depending on the size of the fire). See Heat Dangers in the DMG for more information.

Severe Heat: In severe heat (above 110 F), a character must make a Fortitude save once every 10 minutes (DC 15, +1 for each previous check) or take 1d4 points of nonlethal damage. Characters wearing heavy clothing or armor of any sort take a –4 penalty on their saves. A character with the Survival skill may receive a bonus on this saving throw and may be able to apply this bonus to other characters as well. Characters reduced to unconsciousness begin taking lethal damage (1d4 points per each 10-minute period). A character who takes any nonlethal damage from heat exposure now suffers from heatstroke and is fatigued. These penalties end when the character recovers the nonlethal damage she took from the heat.

Extreme Heat: Extreme heat (air temperature over 140 F, fire, boiling water, lava) deals lethal damage. Breathing air in these temperatures deals 1d6 points of damage per minute (no save). In addition, a character must make a Fortitude save every 5 minutes (DC 15, +1 per previous check) or take 1d4 points of nonlethal damage. Those wearing heavy clothing or any sort of armor take a –4 penalty on their saves. In addition, those wearing metal armor or coming into contact with very hot metal are affected as if by a heat metal spell.

SMOKE INHALATION: Character close enough to be suffering extreme heat from a fire are also close enough to be breathing heavy smoke. They must make a Fortitude save each round (DC 15 +1 per previous check) or spend that round choking and coughing. A character who chokes for 2 consecutive rounds takes 1d6 points of nonlethal damage. Smoke obscures vision, giving concealment (20 percent miss chance) to characters within it.

Roethke
2007-04-20, 09:17 AM
Ah, those look like excellent guidelines on how to deal with fire. Houserules much less necessary

Torek
2007-04-20, 02:11 PM
Splendid answer Justin_Bacon!

Thanks a lot!

DaMullet
2007-04-20, 02:42 PM
Those rules... uh... rule. There's no good way to put that, but in any case, awesome.

brian c
2007-04-20, 02:59 PM
You can house rule that it continues and simply modify the potential damage by how many HPs it took to get through the barrier.

I think that was the recommendation from the Wizards website, yes. Just one of those weird loopholes in the RAW.

RandomNPC
2007-04-20, 08:51 PM
i thought i read in the core books somehwere that a fire (after being set) moves a foot every minuet (this may be killing catgirls, as this may have been a house fire fact i was reading) keep in mind this is in all directions, not just out into one five foot square.

as for setting the fire i'd go with whatever the DM needs to happen, happens. yea it's called railroading, but sometimes you need to make a judgement call.

Enzario
2007-04-20, 10:19 PM
I'm seeing a lot of "combustible material" arguments here. Actually, as per *physics* and *chemistry*, wood actually isn't very inflammable (yes, that means that it doesn't burn... have fun with that sentence:smalltongue: ). Anyway, that's that. Wood in general (in the *science* community) doesn't catch fire easily i.e. a match held under a log for a second or two will not light it on fire. The heat and flame from a fireball is, as per RAW, just a flash, and therefore doesn't light anything on fire except highly combustible materials, such as light paper, oil, and others. However, it may blow other materials apart by damage.


According to *medicine*, I may have killed a few catgirls here...

:edit: @ bacon- thank you so much for making fire that actually poses a threat to PCs!!

Bender
2007-04-21, 01:43 AM
I'm seeing a lot of "combustible material" arguments here. Actually, as per *physics* and *chemistry*, wood actually isn't very inflammable (yes, that means that it doesn't burn... have fun with that sentence:smalltongue: ). Anyway, that's that. Wood in general (in the *science* community) doesn't catch fire easily i.e. a match held under a log for a second or two will not light it on fire. The heat and flame from a fireball is, as per RAW, just a flash, and therefore doesn't light anything on fire except highly combustible materials, such as light paper, oil, and others. However, it may blow other materials apart by damage.

It all depends on the thickness of the wood, furniture that's not too heavy could burn in a few minutes exposure to fire from easy combustibles, depending on the kind of varnish of course

Lolzords
2007-04-21, 09:11 AM
I can't remember where I read it, but it said somewhere that the flame from a fireball flashes and dissapears too quickly for anything to be set on fire by it.

Bender
2007-04-21, 11:50 AM
I can't remember where I read it, but it said somewhere that the flame from a fireball flashes and dissapears too quickly for anything to be set on fire by it.

can't be SRD or PHB because there it says that it does ignite combustibles... :smallamused:

Tor the Fallen
2007-04-21, 12:55 PM
I'm seeing a lot of "combustible material" arguments here. Actually, as per *physics* and *chemistry*, wood actually isn't very inflammable (yes, that means that it doesn't burn... have fun with that sentence:smalltongue: ). Anyway, that's that. Wood in general (in the *science* community) doesn't catch fire easily i.e. a match held under a log for a second or two will not light it on fire. The heat and flame from a fireball is, as per RAW, just a flash, and therefore doesn't light anything on fire except highly combustible materials, such as light paper, oil, and others. However, it may blow other materials apart by damage.


According to *medicine*, I may have killed a few catgirls here...

:edit: @ bacon- thank you so much for making fire that actually poses a threat to PCs!!

If you're going by physics, the amount of energy in a fireball is immense. In a few short seconds it can melt gold. It tranfers A TON of heat in a very short amount of time.

I would be tempted to treat higher level fireballs as creating aflashover (http://en.wikipedia.org/wiki/Flashover) effect.


Housefires:
If you want to start one, start the drapes.
Fire can move very, very fast in a room, especially if you open a door. There's a five foot (or ten foot?) rule for firefighters. Basically, if you're more than 5 feet from a door, you may not have enough time to get to the door by the time the fire gets to you. Fire can move wicked quick.
Log houses/taverns/whatever would burn very, very well, due to the high pitch content in the wood. Flashover would occur quicker, as vaporizing pitch is highly flammable.

Justin_Bacon
2007-04-21, 11:25 PM
:edit: @ bacon- thank you so much for making fire that actually poses a threat to PCs!!

Thanks. (And the same for everyone else's kind words, as well.)


Wood in general (in the *science* community) doesn't catch fire easily i.e. a match held under a log for a second or two will not light it on fire. The heat and flame from a fireball is, as per RAW, just a flash, and therefore doesn't light anything on fire except highly combustible materials, such as light paper, oil, and others. However, it may blow other materials apart by damage.This is a very good point. You could probably try to tweak my rules a little bit to handle it with more accuracy, but I'd say the hardness rules do a pretty decent job of it. (There's a level of accuracy beyond which it's no longer fun to use. :smallamused:)

One of the interesting things to pull out of the numbers, though, is just how intense the flame of a fireball spell really is: If I pour flammable oil over you head and light you on fire, you take 1d6 points of damage per round. A fireball, on the other hand, does a minimum of 5d6 points of damage in a single round. That must be some fairly intense fire. So the idea that it could potentially light thin wood on fire seems pretty reasonable.

Justin Alexander
http://www.thealexandrian.net

Telok
2007-04-22, 10:51 AM
Fun with D&D:

If you pour flammable oil over the head of your average 10th level barbarian and light him on fire, he will take 1d6 damage be mildly annoyed.

The normal reaction of your average annoyed barbarian is to beat someone annoying to death. Because the average barbarian enjoys beating people to death it may take a full minute for him to realize that he is still on fire.

If you are lucky the barbarian will finish beating you to death before putting out the flames. Otherwise the barbarian will probably decide to put the flames out with your face, and then finish beating you to death.

Shhalahr Windrider
2007-04-22, 12:18 PM
Fun with D&D:

If you pour flammable oil over the head of your average 10th level barbarian and light him on fire, he will take 1d6 damage be mildly annoyed.

The normal reaction of your average annoyed barbarian is to beat someone annoying to death. Because the average barbarian enjoys beating people to death it may take a full minute for him to realize that he is still on fire.

If you are lucky the barbarian will finish beating you to death before putting out the flames. Otherwise the barbarian will probably decide to put the flames out with your face, and then finish beating you to death.
I'm gonna have to remember that one! :smallbiggrin:

Leon
2007-04-24, 03:55 AM
Going via what Stormwrack has to say - Yes fireball can start fires but it is rather unlikely, longer burning things have greater chances to start ignition (such as say the items set ablaze by the fire of the ball)