Adding OnWe are considering adding on 450 sq. ft. to the back of our home which would include a kitchen and dining expansion, a full bath and separate laundry room. We are looking for a rough estimate on cost to build. Thanks!September 28 2013 - Irvine0YesReport a ProblemProblemSelect oneOffensive contentIrrelevant contentSpam (pure self-promotion)OtherDetailsYour emailPlease enter a valid email address.Submit CancelContent flaggedWe will review this content. Thanks for helping make the site more useful to everyone. To learn more, read Zillow's Good Neighbor Policy.We're sorry. This service is temporarily unavailable. Please come back later and try again.