I am needing to build up a garden area against my house to create a grade that slopes away from the foundation. The 1950s cedar (?) siding is only about 3" above the mulch as it is now and I need to build the area up above the siding about 2-3". Will aluminum flashing installed over the siding be sufficent to protect it from the contact with the soil/mulch? Is this even the best option for this situation?