I have a vested interest in seeing buildings destroyed during games (but I can't mention why here)
I play FoW and these are the house rules I use:
Rules for Destroying Buildings
Before the game begins the construction type of each building should be specified. There are four types:
Wood: 2 damage points, Saving throw of 5+, Fire Save Modifier of 0
Brick: 3 damage points, Saving throw of 4+, Fire Save Modifier of +1
Stone: 4 damage points, Saving throw of 3+, Fire Save Modifier of +2
Concrete: 5 damage points, Saving throw of 2+, Fire Save Modifier of +3
Note that the number of damage points is for average size houses. Larger structures could have more hits or, alternately, be divided into separate sections which would be treated as individual buildings.
Firing at Buildings
A player can attack a building in two different ways. One is to fire at the teams occupying the building. Any hits on the team may cause ‘collateral damage’ to the building. In this case, fire at the enemy teams as you normally would. Any hit on a team inside the building also causes a hit on the building, which is resolves as explained below. Any building under a barrage or bomb template may be hit like any other target even if they are unoccupied.
A player can also fire exclusively at the buildings. In this case, the building is hit (or ranged in) on a base throw of 3+, which is only modified due to range (for direct fire). Hits scored on the building have no effect on the occupants unless the building collapses, in which case they are affected as explained below. Artillery or bombing attacks may be directed against buildings but will not affect any teams under the template, even if they are not in the buildings (not entirely realistic, but this is to prevent players from firing at buildings to ‘accidentally’ catch enemy troops under the template).
Destroying Buildings
Buildings are destroyed when they suffer enough damage points to destroy them as noted on the table above. The procedure is described below:
1. Weapons must have a firepower rating of 5+ or better to be able to harm a building, although heavy machine guns or vehicle-mounted machine guns have a chance to set a building on fire (see below).
2. If a building is hit it must make a saving throw using the appropriate save value from the table above. If the save is made there is no damage. If the save is failed then the attacker must make his firepower role. If this is successful, the building takes one damage point. Damage can be indicated with a small puff of smoke or other marker.
3. When a building suffers damage equal to its damage points the building collapses. Any teams inside the building suffer a hit and must make a normal saving throw to survive. If they survive, they now occupy the wreckage of the building. Players may wish to experiment with applying negative save modifiers for teams inside large, heavily constructed buildings.
Air Attack
Bombs are much more likely to damage a building than cannon fire (a 500lb bomb has more than ten times the high explosive charge of a 105mm shell). Any building which is under the attack template of an aircraft dropping bombs can be hit and if it is, it will suffer 1D6 hits instead of just one hit. Each hit must be saved for separately as detailed above.
Fire
Buildings may catch fire due to enemy fire. Use the procedure below:
1. Whenever a building suffers a damage point an additional roll is made to see if the building catches fire.
2. The firing player makes a firepower roll for the weapon which inflicted the damage. The firepower rating is modified by the construction type of the building as given on the table above. If the firepower roll is failed, there is no fire. If it is successful the building catches fire.
3. Each turn that a building is on fire it must make a saving throw or suffer another damage point. This is done (appropriately enough) during the fire phase of each player. If the building takes enough damage to collapse due the fire, it does so per the rules above.
4. Teams inside a burning building may attempt to put the fire out during their own movement phase. A successful skill role extinguishes the fire. The team may do nothing else that turn.
5. Any platoon which has teams inside a burning building must pass a motivation test during each of its movement phases to remain in the building. If the test is failed, the player must move all of his teams out of the building.
6. Teams attempting to assault into a burning building must take a motivation test to do so.
7. Heavy and vehicle-mounted machine guns cannot damage a building, but may set it on fire using tracer ammunition. When machine guns hit a building, the building makes a saving throw for each hit. For every unsuccessful save, the machine gun takes a firepower role to set a fire. Note that with the modifier, machine guns can only set fire to wooden buildings.
8. Flamethrowers will automatically set fire to any building hit.
9. Players could modify the chance of fire up or down due to weather conditions if they wish by increasing or reducing the fire save modifier. If you don’t want to be bothered with keeping track of fires, just say it rained heavily before the battle.
Optional Rules
1. Fires Spread – A burning building may ignite other adjacent buildings. Roll for the wind direction Each turn buildings downwind of a burning building may catch fire. The building makes a normal saving throw with a +1 modifier for each inch away from the burning building.
2. Fires Going Out – Fires might go out on their own. In any turn that a fire fails to inflict a damage point on a building, the building gets a saving throw. If it is successful, the fire goes out. If not, the fire continues to burn.
3. Initial Barrage in Big Push Mission – Each building (even unoccupied ones) in the defender’s deployment zone receives 1D6 hits during the initial barrage. The building makes its saving throw as normal. Use a 2+ firepower rating for the attacker.
