While it would have to be "large" for a "mega fire," there are a lot of small and inexpensive things you can do to help protect your home. Things like removing any shurbs around your house are very useful. Won't necessarily save your house, but it's a good start.
They have to be very large (and therefore expensive. Both in terms of land and in terms of maintenance) to protect your house against a mega fire though.
Of course, they could be created in preventative fashion to limit the fires so that the size of the forest fires is limited.