# The Window Sash Details – A Character-Defining Element of a Building

- Link: https://www.oldhouseguy.com/window-sash/
- Published: 2012-05-01T10:29:00-04:00
- Author: Ken Roginski

[⌊historic double hung window⌉⌊historic double hung window⌉[Few elements of a building
contribute more to its architectural character than do the windows and window sashes.

[Click here to open a PDF file, for a great read by James L. Garvin of the New Hampshire Division of Historical Resources on ](https://www.oldhouseguy.com/wp-content/uploads/2014/12/Window_Sashes2.pdf):

 * The evolution of window sashes and muntin profiles
 * Three types of Window glass prior to WWII
 * Window hardware
 * Casings, shutters and blinds interior and exterior
 * Wood sash problems and solutions

## The Interior Window Sash Muntins.

Great question — muntins (the slender bars dividing glass panes) looked simple, 
but their treatment on the **interior vs. exterior** often differed in subtle but
important ways in the 1800s. Here’s a breakdown:

---

### **1. Function and Profile**

 * **Exterior muntins** had to shed water and protect the glazing putty.
    - They were usually shaped with a **slight bevel or slope** on the outside face
      to allow rain to run off.
    - The glass was bedded in putty, pressed in place, and then held with an external
      putty fillet that angled outward to deflect water.
    - As a result, the exterior profile looked **flatter and more utilitarian**,
      with less ornamentation.
 * **Interior muntins** were meant to be seen and integrated with the room’s trim.
    - Their face was often more **refined, crisp, and sometimes slightly more decorative**,
      with a narrow ovolo (rounded) or lamb’s tongue molding profile cut into the
      wood.
    - They didn’t need the bevel for water-shedding, so the interior surfaces tended
      to appear more delicate.

---

### **2. Visual Depth**

 * From outside, muntins appeared **slimmer**, since the sloped putty reduced their
   apparent width.
 * Inside, muntins could look **slightly wider and more pronounced**, because the
   profile was cut into the full thickness of the wood.

---

### **3. Construction Techniques**

 * **Early 19th century (Federal & Greek Revival):**
    - Exterior: thin, delicate muntins with sharp bevels.
    - Interior: fine ovolo moldings, giving a more elegant shadow line.
 * **Mid to late 19th century (Victorian/Italianate/Queen Anne):**
    - Exterior: thicker muntins, but still sloped outward for water shedding.
    - Interior: more complex profiles as interior woodwork became more elaborate.

---

### **4. Glass Size Influence**

 * Early 1800s → glass was small, so muntins were thin (sometimes less than ¾”).
 * By the mid-late 1800s → larger glass panes became affordable, so muntins grew**
   heavier**, and the contrast between inside and outside profiles became more noticeable.

---

✅ **In short:**

 * **Outside:** practical, beveled, flatter, designed to shed water.
 * **Inside:** more decorative, molded, and refined to harmonize with the interior
   trim.

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[⌊Historic Interior Window Muntin design⌉⌊Historic Interior Window Muntin design⌉[

Historic Interior Window Muntin design.

For more information and a better understand of [how replacement windows alter the appearance of a house, read here ](https://www.oldhouseguy.com/windows).