The RoMac Building Supply Whole House Commodity Index fell 0.5% in October to $54,037, down from $54,318 in September. But lower lumber prices don't tell the whole story. OSB climbed for a second consecutive month, fuel costs surged, mortgage rates reached 7.40%, and tariffs continue to put pressure on building costs. Explore the latest commodity price movements, housing market trends, and what builders should watch heading into the final months of 2026.

The September Whole House Commodity Index was essentially flat at $54,321 from August. But that headline number hides significant volatility underneath. OSB jumped 10.7%, Southern Pine 2x4s climbed 15.7%, while Southern Pine 2x12s fell 10.9% and spruce studs dropped 4.8%. For builders and contractors, the takeaway is clear: a flat Index does not mean flat costs. This month’s report looks at the material swings, softer housing market, rising rates, and other cost pressures sha