It is a small part. Labor and land are the biggest costs, accounting for 2/3rds of the cost of building (if you already own the land, that's a different story, but few people do). Materials is 1/3rd of the cost of a home, and then you have electrical, plumbing, HVAC, concrete foundation, roofing/shingles, siding/brick, drywall, fixtures, insulation, driveway, appliances, etc., in addition to lumber in the materials component.
Per the article, lumber is 30% of materials cost, which is 1/3rd of the cost of the home, which means that lumber is 10% of the cost of building an average home. Which means that if lumber goes up 25% due to tariffs, then the cost of building a home goes up 2.5%. Not a significant impact.
I didn't say it was an insignificant cost, just a small cost relative to the total cost of the home. I'd be willing to bet that if you're spending $200K on lumber... you're building one helluva house that not many people can afford, or you're building a log home (which also few people can afford).
And new homes represent a small part of the housing market. A vast majority is existing homes. That's why I said that it isn't going to have a significant impact on shelter costs in the CPI. Most of the money spent on existing homes is on labor to repair things; materials is a much smaller cost.