If a dollhouse was made out of the same material as a real house, how would their weights compare?

varies directly with the cube of their scale factor

e.g if the scale factor is 1: 12 ( 1 inch = 1 foot)
and a tiny table weighs 20 g
then the full size table would weigh
12^3(20 g) or 34560 g
which would be 34.56 kg