Rethinking Insulation for Modern Homes | Build Show Podcast Ep 215

TimberHP is North America's first dry-process wood-fiber insulation board manufacturer — it doesn't cut down trees but upcycles softwood forest-products residuals (mill leftovers, forest thinnings) that used to become paper, in a retooled former paper mill in Maine.

The board is made by thermo-mechanically pulping steam-saturated wood chips, flash-drying them in Dyson-style separator towers, then binding with paraffin and a Gorilla-Glue-like resin in a steam press — yielding a rigid ~9 lb/cubic-foot board with XPS-like compressive strength.

Wood fiber's real edge is thermal mass and diffusivity: it slows heat transfer dramatically — a 9.25-inch board took 8 days to reach steady state in lab testing versus hours for foam — which flattens peak cooling loads in climates with day/night temperature swings.

It handles fire, bugs, and water better than you'd expect: cavity products treated with borates hit Class A (5 flame spread) and reach 1- and 2-hour rated wall assemblies, and the board chars rather than melting into toxic smoke like foam.

Water tolerance is about drying, not repelling — the board can get wet as long as the assembly lets it dry; in a "car wash" test it redistributed and dried moisture within days (nearly self-healing), while EPS trapped moisture for weeks.

It's designed as an easy one-for-one swap in normal wood construction (an R5 board, R10 in thicker profiles), price-competitive with cellulose in cavities and close to XPS on boards — undercutting most mineral-fiber boards; today's addressable market is the Northeast out to the Ohio River Valley.

Beyond performance, the draw is the carbon story — locking up carbon in minimally processed wood that would otherwise be discarded — plus the simple fact that builders already trust and love working with wood.