How do you stop electromagnetic waves in your home?

You cannot.

Well, in theory you could, but not easily!

You would have to shield every electrical cable and appliance, turn off all portable telephones and wireless equipment, etc. And that's for what's being generated in the house.

You could only stop radio waves penetrating the building by shielding the whole thing - and while you're at it black out all the Windows to stop that nasty electromagnetic radiation called "Light".