The buildings are made mostly out of stone and concrete.
/downvoted

True, but you can always add a flamable object that will eventually set the entire building on fire.

also depends what ammunition was used to destroy house :)

for example a HE round above 25% chance etc...

I don't think they'd just fill the houses with flammables in a case of war.

You dont need barrels with fuel and a "shoot me :)" sign for flammables, the average house is FILLED with them. A big closet, a massive bookshelf, a wooden floor, a table. As an ex fire department volunteer anything in the house is flammable, and can be a bitch to extinguish after it was burning for a good while. Now Im sure BI wont be filling houses now with furniture and stuff, but you can always add one massive wooden closet as the flambale item, and once again - wooden floors. So I dont consider finding flammable things in a house to be the issue if thats whats worriying you.

I just don't want houses bursting into flames.

Not only could it be stupid in big urban firefights, but imagine the performance impact.

Upvoted :-)

Firing explosive ammunition at houses will often rupture gas mains causing massive fires that are almost impossible to extinguish.
Just like the aftermath of an earthquake leaving fires spreading as far as the eye can see.

It shouldn't be a chance just anywhere on the house, ammunition type, weather and location should play a role in this feature.

I shall down-vote.
Making this "Fixed" behavior of a generic building..it reduces the use of those buildings under "certain" scenarios.
There was already scripts in ARMA2CO (if not in every ARMA game..)that do exactly what you asking for.

Also..the performance impact was ALWAYS notice-able..so even we had the choice to use those scripts-most times we were avoiding it..

Agreed with ProGamer. Why an arbitrary 25% chance?

Ideally, buildings should go up in flames only if they would ignite in real life, this would require many variables.

I doubt it will happen though - would require lots of work for (arguably) little value.

@Goose - that is exactly the reason it should be about 25%

It would be nice but it would severely cripple performance.

Not necesserily, the smoke wouldnt be much bigger then a blown up car, and you dont destroy that many buildings in the average mission anyways.

But what if you make a "different" mission?

If you make a mission that is already filled with explosions and destroying buildings you already have a massive impact on performance.

Fire on destroyed houses would rather look bad=/

If the effects were better then MAYBE I would agree. At the current state it looks better without fire.

My computer would have a 25% chance of igniting, too. :P

lol