Loading... Please wait...

Plan How to Install an Interior Replacement Transom Window

Introduction to Replacing a Transom Sash

Replacing an interior transom sash is a fairly straight forward process.

  • You will need to learn some basic terminology so that you know how to order — that is, Transoms 101.
  • We want to confirm with you, that you are indeed dealing with a replacement versus another scenario.
  • We will show you how to measure for your new, replacement sash.
  • You will learn how to remove your old sash and install the replacement.

So get started by watching the Transoms 101 video below. Afterward, you will understand the terminology to proceed forward.


Planning 1: Basics and Terminology (Transoms 101)

Learn the parts of a transom, how measurements are made, and the role of the jamb for installation.

Video Summary

Transoms Direct sells transom window sashes -- that is, wood frames around glass.

  • Inside the wood frame, muntins separate glass into decorative panes called lites.
  • A transom pattern is the unique combination of the transom's perimeter shape with the design of its interior lites.
  • By adding a jamb to a transom you can adapt the thinner transom sash to a thicker wall.
  • Not all installations require a jamb.
  • If a jamb is required, the assembly of the transom sash with a jamb is called a transom unit.
  • When ordering, you specify the width and height of the transom sash only -- not including the jamb. This will become very clear as you watch the planning videos.

Planning 2: What is Replacement Scenario?

First, let’s understand a replacement scenario. Your situation should resemble the following:

  • You have a sash, installed in the wall or above a door or opening, that you need replaced.
  • The sash may have broken glass, be too old, or have a muntin pattern that you do not like.
  • You do not wish to change the size of the sash, only replace it.
  • The sash is already installed in a jamb and is secured in place by stop on at least one side.

That last item, “secured in place by stop”, may not be easy for you to answer without a visualization. Watch the next video on sizing a replacement sash for additional context. Note that the video does not mention “replacing a sash” — that’s because installing a new sash (once the old sash is removed) is the same as installing a new sash into a pre-built, cased opening in the wall or above a door or opening. We will tell you how to remove the old sash in the install instructions.


Planning 3: Confirming Replacement Scenario

Now that you understand how a sash is normally installed into an existing jamb, you should be able to look over your replacement scenario and determine if stop is securing the sash on at least one side. The stop may be rounded, square, fancy or simple — but it is likely small — no more than an inch in diameter.

If you find stop on at least one side, your sash can be replaced. Before you proceed forward and order your replacement sash, we recommend that you read our install instructions. Better yet, follow the instructions and go ahead and remove the old sash so that you know it will be “smooth sailing” once your replacement transom arrives.


Select Your Starting Point

 I will be installing a transom sash into a rough opening or new opening. (O-RO)

 I will be installing a transom and door into a rough opening or new opening. (D-RO)

 I have an ordinary door already installed in a wall, and I would like to add a transom above. (D-ONLY)

 I will be installing a transom into a rough opening or new opening. (W-RO)

 My home is complete, and I have a cased opening. (O-FOC)

 My door is already installed with a cased opening built above for the transom. (D-FOC)

 My home is complete, and I have a cased opening. (W-FOC)

 I plan to install my transom into a drywalled opening. (O-FOD)

 I have an installed door with a drywalled opening above for the transom. (D-FOD)

 I plan to install my transom into a drywalled opening. (W-FOD)


COVID-19: All Orders Shipping On-Time. Order Today!
Online Ordering
Custom Built
Delivered in Days