Two ways an item can be destroyed.
1. someone destroys it. No mechanical effect other than that the item is simply gone. It has to be replaced, which takes Ingame time to do. Once enough time has passed, you have a new item. (Unless a significant milestone happened in between, the new item is exactly like the old one, rules wise)
2. this is not in the raw, but i would let a Player decide to have a Focus item destroyed instead of taking a mental consequence in some cases. When absorbing backlash for example. Or maybe even for physical stress, but that would be less likely.
Harry's blasting rod had this fate once or twice, when Harry threw a particularly strong evocation.
I'd let that cancel out, depending on item importance, a mild or possibly a moderate consequence, but not more.
Your house burning down could be a social consequence... how severe it would be is very variable. If you have a really high resources skill... then it might not be worth anything. Marcone would simply get a new place for example. Otoh if you're like Harry, then loosing your Place to live could be a severe or even extreme consequence. (I'd go with severe, but its situational)
I would not let loosing your House replace a consequence. When you loose a Focus item, there is a mechanical disadvantage involved. This disadvantage can replace a consequence.
If your house burns down, there is no mechanical effect. So it works as a description of a consequence (Aspect: "Homeless") but not instead of one. The Same goes for all other possessions you might have.
Loosing them can be a consequence, but it can not replace one.