A lumber shortage during a red-hot housing market has caused the price of single-family homes to jump approximately $36,000 since last April, a new study finds.The analysis, from the National Association of Home Builders (NAHB), emerges as lumber prices in April skyrocketed 250% year over year.The lumber price hike has also added $13,000 to the market value of an average new multifamily home, translating to households paying an additional $119 a month in rent on a new apartment.