Burning Down the Town
 

Someone on the TFT Facebook page asked if anyone had a simple TFT rules/guidelines on how fire may spread. He was fine if the timescale wasn't tactical. He wasn't looking to simulate the ‘physics of fire’ or anything.

I took up the challenge. Below is a suggestion for fire spreading in a village/town.


This is an abstract form of burning a town down.

• This uses a Village Map Hex [or V-Hex] (see ITL p 168 Bendwyn) which equals 10 yards wide.
• Buildings covering a hex are given an ST rating.
• A Fire Attack is 1d6.
• In this simple abstract mechanics, a turn is 1 minute. Smaller Megahex (Melee Map) sized buildings can be represented by small building ST.

There is a gritty abstract mechanics that is also a 1 minute turn and uses a Village Map Hex.

• A V-Hex building would be approximately 7 rooms on the ground floor. A building can come in multiples of Village Hexes and hex ST would be the value of the building in the hex. It will still burn one V-Hex at a time. The total value of a building could be very large indeed.
• The gritty abstract gives the building a decaying (ablative) armor that initially makes fire difficult. This armor is usually the material the building is constructed out of.
• The Fire Attack is rolled and any armor is subtracted.
• If the result is 0 or less, the building does not start burning if it is not already burning OR the fire stays in the same spot if it is already burning.
• A positive fire attack result reduces the ST of the building by that amount and reduces armor by one.
• When the armor of a building reaches 0, there is no more resistance to the fire and the temperature soars.
• When the structure ST is below 25%, there is a chance (4, 5, or 6 on d6) that the building will collapse. Either way, the building continues to burn.
• If a fire started inside the building, the fire will go external (as in reaches the outside) at 75% of ST.

Building External Fire can cause sparks that go beyond the building.
When buildings are within 2 hexes (Melee Map hexes) of each other, the fire can jump buildings, most likely in the direction of any wind.

• Use the normal Fire Attack on the victim structure’s roof while the old one continues to burn. Use die to determine wind direction or just choose a direction. Gap of 3 hexes gives roof protection of 1.
• If the buildings are beyond 2 hexes (Melee Map hexes) of each other, a Flare Up (when flame damage is 5 or 6) will send sparks “4xnumber-of-floors” hexes away for a possible fire attack.

This fire does not take accelerants or magic fire into account. This would increase flame consumption.

Here are several working tables that might help.

Exterior Building Material.............Armor vs Fire
Light, flimsy building..........................0
Standard wooden structure.................1
Wattle & Daub...................................2
?................................................. .....3
Earthen or Adobe...............................4
Brick................................................ 6
Stone............................................. ..8


Protection from Flying Sparks. (Setting the roof on fire)
Once the roof is pierced (reaches 0 armor), use normal gritty rules.

Type of Roof...............................Protection from flying sparks
Thatch/Cloth.....................................0
Wood Shingles...................................2
Clay Tile or Slate................................4 (this is an ablative every other turn)

Accelerants* (Accelerant is consumed in 1 turn)......Add this to Fire Attack
Gunpowder (not explosive)..................+3
Paper/vellum (large amounts)..............+2
Oil............................................... .....+2
Spirit alcohol......................................+2
Pitch, Resins......................................+1
Silk/Cotton (large amounts).................+1
*The accelerant can be in any Melee Hex of the V-Hex. If it is in multiple melee hexes, it will burn for 2 turns instead of 1.

Moisture
Wet............................................... ....Reduce fire attack by 3
Damp.............................................. ..Reduce fire attack by 1
Normal............................................ ..0
Arid (exceedingly dry and hot)..............Increase fire attack by 1
Already Inferno nearby (Temp reaches 1500df)...Increase fire attack by 2

Structure Sizes.....*Add HP for each story
Structures – Footprint....................Melee Hex...../..Village Hex..............# of Stories
Hut/shack........................................Megah ex or smaller/ .x.........................1 story
Small Structure................................4 – 8 megahex/ 1.................................1 or 2 story
Medium Structure..............................8 – 11 megahex/1.5.............................2 story
Large Structure.................................12 – 20 megahex/2 - 3.........................2 or 3 story
Manor............................................. .25 – 35 megahex/3 - 5..........................3 story


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Here is an example of a Simple Burning and a Gritty Burning.
Simple Building ST = 10

Gritty Building: ST=10, Collapse check at ST=3. Armor = 3. Fire Attack = 1d6
75% (round down) of 10 is 7. This is when an interior fire goes exterior. 25% (round up) of 10 is 3. This is when there is a chance of building collapse. Fires can start inside or outside the building. In this example, Damage in these examples is indicated in the beginning of the next turn.

SIMPLE BURNING TOWN

Turn 1
ST=10
Fire roll 1d6=3
Building starts to burn

Turn 2
ST=7
Fire roll 1d6=4
Fire rages

Turn 3
ST=3
Fire roll 1d6=1
Building continues to burn

Turn 4
ST= 2
Fire roll 1d6=3
Building continues to burn

Turn 5
ST=0
Entire building consumed



GRITTY BURNING TOWN

Turn 1
ST=10/3, Armor 3
Fire roll 1d6=3
3-3=0...................Building does not start burning

Turn 2
ST=10/3, Armor 3
Fire roll 1d6=4
4-3=1...................Building starts to burn

Turn 3
ST=9/3, Armor 2
Fire roll 1d6=1
1-2=0...................Fire stays in same spot

Turn 4
ST=9/3, Armor 2
Fire roll 1d6=3
3-2=1...................Building continues to burn

Turn 5
ST=8/3, Armor 1
Fire roll 1d6=4
1-4=3...................Fire increases greatly

Turn 6
ST=5/3, Armor 0
Fire roll 1d6=3
3...........................No more resistance to fire, temp soars

Turn 7
ST=2/3, Armor 0.
Collapse roll 1d6=2...Building does not collapse
Fire roll 1d6=1
1............................Building continues to burn, more than 75% consumed.

Turn 8
ST=1, Armor 0
Fire 1d6=5...............(flare up)
0.............................Entire building consumed
Roll Fire Attack on building across the street


Any comments?

Re: Burning Down the Town
 

Nice. A couple of critiques come to mind:

* 5-10 minutes for an entire building to burn and collapse seems extremely fast to me.

* Seems to me like fires have momentum, so often they take quite a while to get established (or not), but the more of a building catches fire, the more fire there is doing damage unless/until the shape of the building and the position of the fire limits the spread. Details perhaps more than you want to get into, but it seems like the initial damage rate would be much lower than when a large part of a building is on fire, and yet structural collapse would nonetheless tend to be rather later than that. So not a constant rate of damage.

And a couple of questions:

* How would you handle attempts to put out a fire?

* What counts as "a fire attack", and how would TFT damage and fire attacks correspond to the damage used here?

Re: Burning Down the Town
 

I googled speed of household fire and got several "articles" that said about 5 minutes. That seemed real short to me too, but it was a starting mark to get the concept going. My original thought was to have it be 5 minute intervals, but that might be too long.

That is what the building armor is supposed to do: slow down the initial speed of the fire. Perhaps upping armor?
The building armor idea comes from ITL (for burning down doors) and GURPS.

I didn't want to broach that subject just yet. Felt I needed to iron out burning it down first.

------------------------------

The original request was for a non-tactical (not 5 second round) approach to spreading fire. I just decided to use the Village Hex map scale and picked a time interval that might work. Its not really intended for the PCs to be present while you make the fire attack rolls.

So I guess the original FIRST fire attack would be the PCs or NPCs setting fire to a building (or not putting out the fire in the hearth). That would be ITL p19 Fire spell, ITL p 124 Fire as a Weapon and Hexagram #4 p16 Kicking Down the Door.

NOTE: the burning times for those door burnings is with an oil soaked door. I triple the time for non-accelerant fire. Thus a regular door would take 30 minutes to burn to ash.[/QUOTE]

I'm not sure what counts; just had vague ideas. It would usually be a hot spark that smolders a bit or a hot spark that ignites an accelerant. Other buildings on fire perhaps? It could also be an NPC running along with a torch, breaking a window and throwing it in. It's what happens 5 minutes after you pass by chasing the bastard.

I spent a couple of days trying to iron out a direct relation between TFT Tactical fire ass in the above noted sources and something that happens after the tactical is over. I decided to make it abstract from direct TFT rules.

Perhaps what is also wanted is a Tactical Map (5 second round) Fire Spread guideline that can link up with these guidelines?

Re: Burning Down the Town
 

Surely we have some ‘Trippers who are full-time or volunteer firefighters who might have some expertise to lend here.

Re: Burning Down the Town
 

Interesting start to set an array of ground rules. I will have to read it more to really comment on it.

I concur with Shostak. It would be nice for an experienced firefighter to place their filter over this info.

Re: Burning Down the Town
 

BTW, shouldn't we move this to the House Rules sub-forum?

Re: Burning Down the Town
 

YES, you are absolutely right. Me Bad.

I should have realized that when I started the post.

Please go to the House Rules sub-forum
http://forums.sjgames.com/showthread...69#post2434569