Ready-To-Install Means Adding a Transom Jamb

Ready-to-Install Model AC-2 Transom Sash with Optional Jamb Whereas the transom sash is the carrier for the glass (just like a sash on an ordinary window), the jamb is the perimeter piece that connects the sash to the wall.

The jamb surrounds the transom sash and holds it in place.

Once the sash is in place, the jamb is mulled (that is, attached) to the door jamb below or attached directly to the studs (on sides) and header (above) the opening. This can be done with trim nails or screws.

See Basic Installation.

What We Need to Know to Build Your Jamb

  • Jamb material grade: that is, which type of wood to use for jamb (paint or stain grade).
  • Wall thickness or door jamb thickness.

Jamb Material Grade

This is easy. Use the following guide on what grade of jamb to order:

If you ordered a Paint Grade sash… order a Paint Grade Jamb.

If you ordered a Stain Grade sash, and casing will be painted... order a Paint Grade Jamb.

If you ordered a Stain Grade sash, and casing will be stained… order a Stain Grade Jamb.

If you order a Stain Grade jamb, we will build your jamb with the same wood species as you ordered for the sash.

Wall Thickness

Wall thickness is just as simple as it sounds. To find it, you can copy from a door below, calculate it, or measure it.

  • Copy From a Door Below. If your transom is above an interior door and you can learn the door jamb thickness, then order the transom jamb with the same jamb thickness as the door. Typical measurements for door jamb thicknesses are 4-9/16", 5-1/4" and 6-9/16" (you will see why below).
  • Calculate. If you know the thicknesses of the materials that were used to construct the wall, you can calculate the wall thickness. This calculation is usually the sum of thicknesses of the framing (wood or metal studs) and the drywall (1/2" or 5/8" gypsum wallboard). The sum of the "sandwich" of these materials determines wall thickness. You can calculate this yourself or ask your contractor. This method does not work for plaster walls in older homes (as they vary in thickness).
  • Measure. If you can physically measure the thickness of the wall from outside plane to outside plane, this is a suitable measurement for the jamb as well. For concrete block, masonry or plaster walls, this is usually the best option. Be sure that this measurement is from plane-to-plane of the actual wall -- do not include the thickness of casing or other items applied on top of the wall (as these will be applied on top of the jamb as well).
  • Common Wall Thicknesses. The following thickness options will listed on the Order Page for your convenience.

    Name Jamb Thickness Typically Used For: Calculation or Note
    2x4 Wall 4-9/16" 2x4 Wall with 1/2" Drywall Each SIde 1/2" drywall + 3-1/2" stud + 1/2" drywall + 1/16" tolerance
    2x6 Wall 6-9/16" 2x6 Wall with 1/2" Drywall Each SIde 1/2" drywall + 5-1/2" stud + 1/2" drywall + 1/16" tolerance
    2x4 Deep Wall 5-1/4" Older home with 2x4 plaster walls OR fire rated 2x4 walls Actual wall typically measures from 4-9/16 to 5-1/4". Cut down jamb on-site with table saw.
    2x6 Deep Wall 7-1/4" Older home with 2x6 plaster walls OR fire rated 2x6 walls Actual wall typically measures from 6-9/16 to 7-1/4". Cut down jamb on-site with table saw.
    Custom Varies Built-to-Order Based on your calculation or measurement. Place actual thickness measurement in SPECIAL INSTRUCTIONS box on second page of checkout.


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Kind Words From Our Customers

"I want to take a moment of your time to tell you how pleased we are with your product and the service you provided. I am a do-it-yourselfer, and your time to explain the way doors are measured was greatly appreciated. I am now smarter for it. Your product was exceptionally well made and easily could be stain quality even though we bought paint grade. The order was quickly filled, and we were able to complete that portion of our project ahead of schedule. Thanks again, and we will gladly recommend you guys to our friends." --A.D., Sanford, FL