My house built in 2005 has washer on the right. The house in which I grew up, built in 1964 was washer on right. The house my parents bought in 1980, built in 1972, has washer on the right. It was done that way in all three cases so the dryer vents directly through an outside wall. The wall behind them was/is an inside wall -- can't vent the dryer into a bedroom, bathroom, or kitchen!