Yes, lumber futures as measured by the front month futures contract have fallen sharply but the latest price data (June) gathered by Engineering News Record for particleboard underlyment continues to rise.
Particleboard is not the only increase in construction costs. The 20-city average price of PVC pipe and 1 1/2 inch copper water tubing are also on the rise as can be seen from the seasonality charts below.
According to Lennar (whom reported last evening) thus far builders have been able to pass along building material costs to home buyers.
The front month lumber futures contract may have fallen from the May 10th highs by 66.4% to date…kryptoherald.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F9306b1f1-b5d7-436c-afb6-03ba5500e1a6_1487x909.png">