Fire Rated Wood Frames

Fire Rated wood jamb frame

Advancements in composite fire materials have created an opportunity for architects, interior designers, and owners to choose striking wood fire rated jambs in lieu of hollow metal frames. Perfect for the spectrum of projects from condos, to hospitality projects, to office tenant finish outs, to senior/assisted living centers, and, of course, historic renovations.

The combination of wood veneers with composite materials has resulted in the capabilities listed below, ranging from 20 minute fire ratings to 90 minute fire ratings. All products manufactured by Grandoors are made in the US, do not contain added urea formaldehyde, and are listed with QAI Laboratories.

Available primed/paint grade or in an assortment of wood veneers. Gasketing can be                                  provided upon request.   Contact us about unique hardware capabilities including 45 minute fire rated overhead concealed door closers.

Wood Fire Jamb Capability Chart

Single (Max Size)Pair (Max Size) Minimum Frame Width Single Rabbet or Double Rabbet Rough Opening Size Custom Options 
20 Minute
Fire  Rating
 4/0 x 9/0 8/0 x 9/0 4 1/2" YES
 Door Width: +2"
Door Height: +1 ½"
 45 Minute
Fire Rating
 4/0 x 9/0 8/0 x 9/0 4 1/2" YES
 Door Width: +2"
Door Height: +1 ½"
60 Minute
Fire  Rating
  4/0 x 9/0  8/0 x 9/0  4 1/2" YES
  Door Width: +2"
Door Height: +1 ½"
90 Minute
Fire  Rating
 3/6 x 9/0 7/0 x 9/0 4 3/4" YES
   Door Width: +2"
Door Height: +1 ½"

*All Hardware and corresponding preps are to meet NFPA 80 requirements.  Preps are done by Grandoor Frames and require completed machining sheet by client.

**Each Hinge requires one standard screw to be replaced with 2" length screw to secure door to wall stud

*** Concealed Overhead Closers (LCN/Dorma/etc) with closer body in JAMB header available up to 45 minutes.


Double rabbeted fire rated wood door frame 45 minutes
Fire Rated Wood Jamb (Double Rabbeted)
Single Rabbet 60 minute wood door frame
Fire Rated Wood Jamb (Single Rabbeted)

Fire Rated Wood Side Lite/Transom/Borrowed Lite Capability Chart

     Certain situations call out for additional light between rooms, but were faced with limitations should the opening need to be fire rated.   Grandoor Frames now offers fire rated sidelites, transoms, and borrowed lites in both 20 minute ratings and 45 minute ratings.   

Maximum Dimension
 (including door) 
Minimum Frame Width Rough Opening Size Max Glass Size
 20 Minute Sidelite/Transom 8/0 x 10/0 4 1/2" Add 1" to frame size (½" gap around frame)---
45 Minute Sidelite/Transom  6/0 x 10/0 4 1/2" Add 1" to frame size (½" gap around frame)
 20 and 45 Minute Borrowed Lite 6/0 x 10/0 4 1/2" Add 1" to frame size (½" gap around frame) 24" x 77"

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Have something really out of the ordinary or truly "grandeur?"   We didn't call the company "Grandoor" for nothing!  Contact us directly with your requirements.

Unique Questions we get asked

Q: What is the widest jamb you can provide?   

A:  While there is a jamb minimum, there is NO maximum.   We have provided jambs 12" wide and 24" wide.   The sky's the limit.

Q: Can I get the fire rated door and frame prehung?

A:  We designed our frames to be the easiest to install in the industry using our simplified angle brackets.   All jambs ship knocked down (in 3 pieces) with installers in mind.   No need for shims, mineral wool, or nailing right through the stop.

Q: Can I request a small door and frame?

A: Sure, we have seen requests for small fire rated doors for special areas.  Frames are all customized to order.

Q: Are fire rated wood frame affordable?

A:  ABSOLUTELY.  We find Grandoors to have the most affordable fire rated wood frames available on the market today.  This is achieved by using our own proprietary fire tested materials to achieve the fire ratings.   

Q: Can I use a concealed overhead closer?

A: Yes, the CLOSER body can be concealed in the jamb header up to 45 minutes.

Q:  Is there a minimum order size?

A:  No, we are happy to supply one or more frames.   Sometimes this is required in a house-to-garage door where a 45 minute, 60 minute, or 90 minute frame is required.   Other projects such as historic preservation or office space require just one frame in a fire rated application.

Q:  Can I use a Grandoor frame with another manufacturer's wood door?

A:  Absolutely!   Grandoor Frames can be paired with any fire rated door on the market.