Fire rated wood jambs (20 min / 45 min / 60 min / 90 min). More and more, a wood jamb is being preferred as the choice look over a hollow metal jamb, however fire ratings and cost have historically limited its appeal. This is why Grandoor was created. Using a composite veneered jamb, architects, developers, and homebuilders can now achieve fire ratings easily and affordably. USA Made and can be paired with any fire rated door on the market.