The typical door opening in commercial and institutional buildings consists of a wood door installed in a plain painted metal jamb. Often, the door is a of architectural quality in a premium veneer with an enhancing transparent finish. A metal jamb does not properly extend that enhancing.

Wood jambs began disappearing from commercial projects when stringent fire codes demanded 20 to 90 minute fire ratings on doors and jambs in many openings. Perhaps, specifiers thought that because so many openings in commercial buildings were required by modern fire codes to be rated it was easier to simply specify metal jambs for all openings.

As a producer of custom wood work for over sixty years, we are proud to produce our Warnock Hersey approved FIRESPEC 20, twenty minute labeled wood jamb. In addition to offering architects and designers the opportunity to match the species of the door chosen for their projects, the installation of our 20 minute wood jamb, unlike metal jambs, can be delayed until doors are ready to be installed. This does not delay any other trades and best assures that the jamb will be installed and maintained plumb and square. Damage from preceding trades is thereby avoided.

Our FIRESPEC 20 jamb can be used with an almost unlimited number of casing profiles as no unusual thickness of casing is required (see typical sections & OPTIONAL door casings illustration). Many of our most popular profiles of casing are shown on the jamb illustrations and we have tooling for many more.  We can also produce tooling at our facility to machine any custom profile required.

Maximum size of an opening using the FIRESPEC 20 jamb is 6'-0 x 9'-0 with a minimum wall thickness of 3 3/4". Non-standard opening sizes and wall thicknesses are not a problem to accommodate which is especially convenient in restoration projects. The FIRESPEC 20 is available in any wood as dense or denser then poplar. This includes almost all commercially used domestic and imported hardwoods and some softwoods.

Hinge and strike plate machining is included with the FIRESPEC 20 jamb. Mitering of stop and casing is also available. Properly rated hardware must be used with the FIRESPEC 20 as would be required on any other 20 minute installation. Jamb components are shipped unassembled. Legs are rabbeted to receive heads and heads are cut to length.