Consider this a test case for inclusion in the core rules later:
Buildings and their destruction
In some settings and scenarios, outright destruction of buildings (and other scenery) is a possibility.
This is often well suited to games where your units represent large forces, very powerful units (such as giant monsters or super heroes) or have weaponry specifically intended for the purpose (such as siege guns).
You should evaluate which units on your table will be capable of inflicting the required level of damage.
For example, you can't bring down a concrete building with machine gun fire, but a unit with a flamethrower could "destroy" a forested area.
In a game of infantry squads and light tanks, no unit may be able to inflict the required damage while a giant robot battle might see all of them so capable.
For particularly large terrain features, it's often more sensible to divide them into Blocks of 3x3 or 4x4 square inches.
If playing in 6mm (or similar smaller scales) each stand-alone building model or terrain piece is usually one Block.
Attacking a structure
Attacking a structure is done in the same fashion as attacking any other target.
Units armed with "Assault" equipment (such as demolition charges or power fists) must be within 6" (representing running up, placing the charges and getting away) while units capable of inflicting building damage at range can fire as normal.
A typical Hit roll is 5+ (demolition charges), 7+ (Weak/moderate structure under fire, powered melee attack), 9+ (reinforced/defensive structure).
As always, adapt as you need.
Trained engineers or siege troops should receive a +1 to their dice roll.
You may assign specific Damage rolls to anti-structure weapons. Typically, 1D6 is fine.
2D6, pick high for super-weapons specifically intended for the purpose.
Otherwise, simply take the basic Damage roll and scale it down once for vehicles and heavy weapons units and twice for infantry.
This means a vehicle/heavy weapons team will inflict 1D3 Damage while infantry would inflict 1 Damage.
Mega-units inflict normal damage.
As with other units, when 7+ Damage has been accumulated, the structure collapses.
Any units contained within a collapsing structure sustains 1D6 Damage.
Buildings are replaced with a rubble field. Place any survivors there.
Other features are replaced with whatever seems appropriate to the situation.
Units representing a single character receive an Escape roll of 8+ on 2D6 (7+ for Hero-types).
A successful escape inflicts only 1 Damage, otherwise the character suffers 1D3 Damage.
Any unit within 1" per floor of a collapsing structure suffers 1 Damage.
Other terrain features typically do not inflict area damage when collapsing.
At the end of each game turn, roll a D6 for each damaged structure.
If the roll is equal or below the accumulated Damage total, increase Damage by 1 point.
Give these options a try if you play a game where they might fit.
They are under consideration for inclusion in the core rules, so don't hesitate to get in touch.