btw I'm pretty sure copper mesh will not do anything to a magnetic field, considering its Mu-R (relative permeability) is 1. (this means that as far as magnetic fields are concerned, copper is the same as free space.)
I'm also pretty sure lead won't do you much good either, because it's in the same class (diamagnetics) as copper, silicon, carbon, and inert gasses. Maybe if the lead sheet has something other than lead in it, but in that case you'd want to leave the lead out of your house and get some of whatever other material is helping.