I don't wish to appear negative, but if your house is constructed the way you describe it, there will be a grid of steel reinforcing rods in the walls and floors. This may cause trouble, so I suggest you try before you buy if that is possible. To be fair, it may well work satisfactorily because it uses a pretty short wavelength signal, but with your sort of house there is a bigger risk of it not working than one constructed without using steel reinforced concrete.
P.P.